Midterm 1 (lectures 1-13) Flashcards
(275 cards)
1
Q
How diverse are the vertebrate species? (Facts to know)
- extant species
- discovered species
- extinct species
- living species percentage of total
A
Over 63,000 extant species.
100-200 species discovered every year.
More than five million extinct species.
Living species only 1 percent of total.
2
Q
Extant vs extinct
A
extant: still living
extinct: no longer exist
3
Q
Name the two major groups.
A
- non-amniotes
2. amniotes
4
Q
Which are aquatic and terrestrial vertebrates, the non-amniotes or amniotes?
A
non-amniotes=largely aquatic
amniotes=largely terrestrial
5
Q
What are the non-amniotes and give examples.
A
Embryo enclosed and protected by membranes produced by reproductive tract of female.
ex) jawless fishes (Agnathans), cartilaginous fishes (Chondrichtyes), bony fishes, amphibians (salamanders, frogs, caecilians).
Largely aquatic.
6
Q
What are the amniotes and give examples.
A
Additional set of three membranes associated with embryo (fetal membranes). One of these is the amnion.
ex) turtles (Testudinia), Lepidosauria (lizards, snakes, tuatara), Crocodilia, Birds (Aves), Mammals.
Largely terrestrial.
7
Q
Which three species are part of the “reptiles?”
A
turtles (Testudinia) Lepidosauria (lizards, snakes, tuatara)
Crocodilia
8
Q
Why do we use classification?
A
- useful for organization
- reflects evolutionary relationships
9
Q
Taxon and Taxa
A
- named taxonomic unit at any level
- plural=taxa
10
Q
Binomial nomenclature
A
- scientific naming of species, standardized by Linnaeus
- Genus+species (always italicized)
11
Q
How does hierarchy of classification work?
A
- higher levels of classification are more inclusive (Kingdom)
- lower levels are more exclusive (Species)
- Should reflect degree of relatedness or evolutionary relationship (when they last shared an ancestor, not necessarily how similar they appear)
12
Q
Which are the levels of classification? List them in order of most inclusive to most exclusive.
A
- Kingdom (e.g., Animalia) includes many phyla *most inclusive
- Phylum (e.g., Chordata) includes many classes
- Class (e.g., Mammalia) includes many orders
- Order (e.g., Carnivora) includes many families
- Family (e.g., Felidae) includes many genera
- Genus (e.g., Felis) includes many species
- Species (e.g., concolor) *most exclusive
13
Q
Cladistics
A
- hierarchical classification of species based on evolutionary ancestry
- recognizes only groups that are monophyletic (one tribe)
14
Q
Clade
A
(“branch”) = an evolutionary lineage
15
Q
Nodes
A
node= common ancestor of the tree
16
Q
Phylogenetic systematics
A
Use of cladistics, a hierarchical classsification of species on evolutionary ancestry/relationships. Excellent way to visualize and summarize interrelationships among taxa.
17
Q
Monophyletic
A
- “one tribe”
- where same ancestor gave rise to all species in that taxon and to no species in any other taxon
18
Q
How do we identify monophyletic groups?
A
- On basis of derived (apomorphic) characters
- presence of synapomorphy (shared derived characters) helps identify common ancestry
19
Q
Apomorphy= derived
A
character different from ancestral condition (novel trait)
20
Q
Plesiomorphy
A
ancestral character
ex) feathers in birds, hair in mammals, jaws in vertebrates
21
Q
Synapomorphy
A
shared derived characters
ex) Notochord of Chordates
22
Q
Symplesiomorphy
A
- shared ancestral characters
- uninformative
- retention of ancestral characters does not necessarily indicate recent common ancestry
ex) mammals (with hair) more closely related to each other, but absence of hair doesn’t indicate close relationship
23
Q
Homologous
A
- characters are the same due to common or shared ancestry, regardless of whether or not structures perform the same function in extant organisms
- ex) pectoral fins, forelegs, wings
- ex) swim bladder of fish=lungs of tetrapods
24
Q
If a derived character (structure) were to evolve independently in different lineages, will it be useful for determining evolutionary relationships?
A
No.
ex) endothermy (“warm blooded”) in birds and mammals evolved independently in each lineage
25
Analogous characters or Homoplasy
- resemblance between species from different evolutionary branches
- similar ecological roles but arose independently
- plas=form
- refer to structures which perform a similar function but are not necessarily homologous
- ex) gills of fish and lungs of tetrapods
26
What are the various causes of homoplasy?
1) convergent evolution
2) parallel evolution
3) evolutionary reversal
27
Causes of homoplasy: Convergent evolution
similar characters evolve independently in separate lineages which diverged a very long time ago
ex) bats and birds do not have a common ancestor with wings
28
Causes of homoplasy: Parallel evolution
species that diverged relatively recently develop similar specializations
ex) elongate hind legs in arid adapted rodents in Africa and North America
29
Causes of homoplasy: Evolutionary reversal
independent evolution of trait (not indicative of ancestry)
ex) re-evolution of streamlined body & fins of aquatic whales & dolphins whereas sharks retained these traits from the ancestral condition
* Independent evolution of trait (not indicative of ancestry)
30
Cladistics doesn't recognize which two types of taxa?
1) Polyphyletic taxa: members are derived from two or more unrelated lineages; also called artificial grouping or homoplasy (plas=form)
2) Paraphyletic taxa: don't include all species derived from common ancestor
31
What are some traditional groups that are paraphyletic?
- Dinosauria (dinosaurs) should include birds
- Reptiles should include birds but still useful descriptive terms
- chimps (Pongidae) and humans (Hominidae) are more closely related but don't like to include ourselves in that relationship
32
Sister groups
monophyletic lineage most closely related to monophyletic lineage being discussed
ex)Pterosaurs are sister to dinosaurs
33
Crown groups
taxa at ends of branches (extant species)
34
Stem groups
- extinct forms that preceded the point where first member of crown group branched off
- May lack all of derived characters of crown group
35
In the Phylum Chordata, which three subphylums exist? Which two subphylums are the "non-vertebrate Chordates?"
1) Subphylum Vertebrata
2) Subphylum Urochordata (tunicates, sea squirts)
3) Subphylum Cephalochordata (lancelets)
* 2 and 3 are "non-vertebrate chordates"
36
Which are the two ways in which Chordates can develop?
1. Protostomata (first mouth, blastopore=mouth) *paraphyletic
2. Deuterostomata (second mouth, blastopore=anus) *monphyletic therefore, deuterostome development synapomorphy indicating shared ancestry
37
Where do Chordates fit in relation to other animals?
- 30 other animal phyla
-Chordates superficially resemble other active animals (e.g., insects)
-But more closely related to phylum Echinodermata
and phylum Hemichordata
-Chordata, Echinodermata, Hemichordata are the only deuterostomes
38
Name the five synapomorphies (derived characteristics) that appear during the development of all Chordates and distinguish them as a monophyletic group (whether or not they persist in adulthood).
1) Notochord
2) Dorsal Hollow Nerve Cord
3) Postanal Tail
4) Pharyngeal Gill Slits
5) Endostyle/Thyroid Gland
39
Synapomorphies of all Chordates: Notochord
-gives Chordata its name
-Semi-rigid rod made of large cells with tough
connective tissue covering
-Incompressible, preventing shortening, but flexible
-Point of muscle attachment
-Replaced by vertebrae in most vertebrates
40
Synapomorphies of all Chordates: Dorsal Hollow Nerve Cord
- Ectodermal cells grow upward at dorsal midline, forming a hollow tube
- Forms spinal cord
- Ventral, solid and of mesodermal origin in Arthropoda, annelids, etc
- Appears to be induced by presence of notochord
41
Synapomorphies of all Chordates: Postanal Tail
- Segmented, muscular tail
- Extending beyond gut region
- Present in all chordates during embryonic development
42
Synapomorphies of all Chordates: Pharyngeal Gill Slits
- Paired openings in walls of anterior pharynx
- Likely evolved as filter feeding mechanism
- Modified for respiration in fish
- Present in tetrapod embryos but modified during development
43
Synapomorphies of all Chordates: Endostyle / Thyroid Gland
-Endostyle in adult non-vertebrate chordates and
larval lampreys
-Secretes mucus to trap food
-Homologous to thyroid gland of vertebrates
-Groove of ciliates glandular tissue on pharynx floor
-Larval lamprey endostyle metamorphoses into adult thyroid
44
Subphylum Urochordata: Facts
- tunicates and sea squirts
- Uro=tail, so notochord extends into tail
- Approx. 2000 species
- All marine
- Approx. 100 species with free-swimming adults
45
Subphylum Urochordata: Adult forms vs Larvae forms
-Most species have sedentary adults
-Adult with large ciliated pharynx for filtering, encased in fibrous ‘tunic’
-Adults only have 2/5 synapomorphies of Chordates: endostyle and pharynx
-Free-swimming larvae with all chordate characteristics
-Transformation of larval tunicate involves loss of
tail, notochord, and dorsal nerve cord
46
Subphylum Urochordata: Larvacea
- Group of urochordates which never transform
- Reach sexual maturity in larval form
- Paedomorphosis
- Adults retain notochord and tail and dorsal nerve cord
47
Paedomorphosis
retention of larval characteristics by sexually mature adult
48
Subphylum Cephalochordata: Facts
- Cephalo=head, notochord extends into head
- 22 species small, superficially fishlike marine animals (in salt water)
- lancelet or amphioxus, Branchiostoma lanceolatum
49
Subphylum Cephalochordata: Characteristics and derived traits
-Mostly burrowing, sedentary
-Anterior elongation of notochord aids in burrowing
-Pharyngeal gill slits for filter feeding, not gas exchange
-Derived traits:
○ Skin forming vertebrate-like tail fin (caudal fin)
○ And obvious muscle segmentation (myomeres)
50
Myomeres
blocks of striated muscle fibres separated by sheets of connective tissue
51
Subphylum Cephalochordata: What new discoveries have been made regarding the relationships between the three subphylums Cephalochordata, Urochordata and Vertebrata?
- Caudal fin and myomeres previously considered to be synapomorphies showing cephalochordates and craniates (vertebrates) to be sister taxa
- But new (molecular) evidence suggests Tunicates and not cephalochordates are the closest living relatives of vertebrates
- Shows urochordates and vertebrates as sister taxa
- Previous assumption that earliest chordates sessile and that cephalochordates and vertebrates evolved from tunicate-like ancestor
- Now suggestions that sessile adult stage in tunicates is derived
- Ancestral form? Larvacea
- Sessile tunicates specialized, not “primitive”
- Evolution sometimes messy
52
Why is the Subphylum Vertebrata also termed Craniata in older references?
-not all animals included in this subphylum have vertebrae
53
To be considered in the Subphylum Craniates, what characteristics are key?
1) brain in a cranium
2) paired sensory organs
3) pharyngeal arches respiratory
* excludes vertebrae and dorsal fin
54
What are the five synapomorphies of Subphylum Vertebrata?
1) brain in a cranium
2) paired sensory organs
3) pharyngeal arches respiratory (no longer for filter feeding)
4) vertebrae (secondarily lost in hagfishes)
5) dorsal fin (secondarily lost in hagfishes?)
* in some lineages, these will be secondarily lost or modified
55
What are agnathans?
- means 'no jaws'
- a Superclass of jawless fish in phylum Chordata, subphylum Vertebrata
- a paraphyletic group (including extinct jawless fishes)
56
What are the two living agnathans?
1) hagfishes: lack vertebral elements altogether and lack of eyes = plesiomorphic traits have been lost secondarily, is a Craniate but not Vertebrate
2) Lamprey: have rudimentary cartilaginous vertebrae
* molecular evidence showing the two are monophyletic and sister taxas
* was once a more diverse group
57
Vertebrates are larger, more active by finding prey and evading predators. Therefore, they need which of the following to be able to do these things?
- Organ systems (instead of relying on diffusion or ciliary action)
- Higher metabolic rate (greater oxygen intake, circulatory system)
- Muscles and skeleton
- Flexible but protective outer covering
- Some tissues mineralized with unique type of mineral, hydroxyapatite (Ca, P)
- More resistant to acid (e.g., lactic acid) than calcium carbonate in mollusk shells
58
Cephalization
Concentrated, recognizable head end
59
Vertebrates display which important physical characteristics?
1. Distinct cephalization with paired sensory organs (Nerve cord expanded into brain)
2. Inner ears include at least one semicircular canal (Important for sensing orientation) and lateral line to detect movement and vibration)
3. Pharyngeal gill slits become respiratory in adults. In non-vertebrate chordates, gas exchange across body surface; pharyngeal arches for filter feeding.
60
Non-vertebrate Chordate vs. Generalized Primitive Vertebrate: Brain and Head End
Non-vertebrate: no cranium, simple brain (cerebral vesicle), only photoreceptive frontal organ
Vertebrate: cranium around brain, tripartite brain, multicellular sense organs
61
Non-vertebrate Chordate vs. Generalized Primitive Vertebrate: Pharynx and Respiration
Non-vertebrate: Gas exchange across body surface; gill (pharyngeal) arches for filter feeding. Pharynx not muscularized. Water moved by cilia.
Vertebrate: Gill arches support gills used for respiration. Musculature for active pumping
62
Non-vertebrate Chordate vs. Generalized Primitive Vertebrate: Feeding and Digestion
Non-vertebrate: filter feeders, food passage by ciliary action, intracellular digestion
Vertebrate: most particulate feeders, larger gut volume, gut muscles to move food (peristalsis), digestion by enzymes in gut lumen
*exception=hagfish: products absorbed by cells lining gut
63
Non-vertebrate Chordate vs. Generalized Primitive Vertebrate: Circulatory System
Non-vertebrate: no true heart, single-chambered pumping structure, no neural control, open system with large blood sinuses, accessory pumping regions, blood not involved in gas transport, no respiratory pigment
Vertebrate: ventral pumping heart, with sinus venosus, atrium, ventricle, neural control regulates pumping (*except hagfishes), closed with extensive capillary system (*except hagfishes), red blood cells with hemoglobin, accessory pumping regions=*hagfish only
64
Non-vertebrate Chordate vs. Generalized Primitive Vertebrate: Osmoregulation
Non-vertebrate: body fluids same ionic composition as seawater, no specialized kidneys
Vertebrates: body fluids more dilute than seawater (*except hagfishes since it is lots of work to maintain osmoregulation), glomerular kidneys
65
Non-vertebrate Chordate vs. Generalized Primitive Vertebrate: Locomotion
Non-vertebrates: no median fins beside tail fin
Vertebrates: median fins, caudal fin with dermal rays, dorsal fins (*except in hagfishes)
66
True or False? There are more than 60,000 extant vertebrate species.
*on exam
True
67
True or False? Extinct vertebrate species likely outnumber extant vertebrate species by about 100:1.
*on exam
True
68
True or False? Amniotes include the fishes and amphibians.
| *on exam
False. These are non-amniotes.
69
True or False? Biological classifications will change as our understanding of the interrelationships among taxa changes.
*on exam
True
70
True or False? Only monophyletic taxa are recognized in cladistics.
*on exam
True
71
What was observed in the early vertebrate fossils discovered in China 520 years ago?
- 3 cm long, fish-shaped
- Notochord, cranium, paired sensory structures, myomeres, gill pouches
- Dorsal fin (derived character lacking in hagfishes)
- No bone or mineralized scales
72
In the extant vertebrates, name some examples for the following:
A) no jaws, no bone
B) jaws, no bone
C) jaws, bone
A) hagfish and lampreys
B) cartilaginous fish
C) bony fish and tetrapods
73
Which evolved first, jaws or bones?
Bones
74
Conodonts (Conodonta): Facts
- First known from microfossils called conodont elements
- Widespread and abundant in marine deposits from Late Cambrian to Late Triassic (approx. 500 mya – 200 mya)
- Mineralized structures, kept well during fossilization (Mineralization is an anapomorphy)
- Once thought to be skeletal parts of marine algae or invertebrates, but made of apatite, similar to dentine
75
Apatite
- Mineralized calcium compound unique to vertebrates
| - Likely toothlike elements of vertebrates
76
Conodonts (Conodonta): What helped determine that they were vertebrates?
Vertebrate status confirmed with complete fossils showing:
- Notochord
- Cranium
- Myomeres
- No evidence of gill slits (lost secondarily?)
- Pharynx (in filter feeding) adapted to operate teeth
- Also large eyes and fins with rays
- Likely more derived than soft-bodied, extant jawless fishes
77
True or false? Extinct means primitive.
False. Extinct does NOT mean more primitive.
78
Ostracoderms: Facts
- “Ostracoderms” (= Shell Skins)
- Bone fragments from around the world (480–500 mya)
- Later complete fossils (400 mya)
- Approx. 10–50 cm long
79
Ostracoderms: Physical characteristics
- bony armour, not an actual shell
- Still no hinged jaws
- Also more derived (more novel traits) than extant agnathans (hagfishes and lampreys)
- ex) cerebellum, olfactory tract = additional anapomorphies
- physiological capacity to form mineralized tissues in dermis (dermal bone)
80
Dermal bone
- Not external to skin like a shell
- Little toothlike elements (odontodes) formed in the skin
- Base of acellular bone overlain by layer of epidermis
- Virtually unmodified in placoid scales of sharks
- Aggregations form larger scales, plates, and shield on heads of ostracoderms and early bony fishes for protection
- Human teeth similar and likely homologous
- But origin of this ability a puzzle
- Earliest-known mineralized structures no less complex than that of living vertebrates
- *No (known) transitional stages
81
Name the advantages for selection of mineralized tissues for organisms.
- Protection: Defence against predators (e.g., eurypterids)
- Sensory: Insulating coat around electroreceptors that enhanced prey detection
- Mineral storage and regulation: Ca and P (relatively rare element, especially in fresh water)
82
Which evolved first? Freshwater or saltwater organisms?
Saltwater then freshwater
83
How do Ostracoderms fit into evolution as a group?
- Diverse group
- Paraphyletic group: more derived groups (e.g., osteostracans) more closely related to jawed vertebrates (gnathostomes) than to other ostracoderms (e.g., heterostracans)
84
Ostracoderm: Heterostraci: Pteraspida
- Pteraspida (“Wing Shield”)
- Pter=wing or fin
- No paired fins or jaws
- Have Hypocercal tail
85
Clade Myopterygii
Myopterygii = “muscularized fins”
- monophyletic
- Paired lateral fin folds, dorsal and anal fin
86
Ostracoderm: Osteostraci
- derived Cephalaspid
- Appearance of perichondral bone (at least in skull)
- Calcified cartilage
- Cellular dermal bone
- Pectoral fins with narrow base
- Heterocercal tail
87
Identify the correct progression through evolution of:
A) Dermal bone
B) Perichondral bone
C) Mineralized teeth
1) mineralized teeth
2) dermal bone
3) perichondral bone
88
How did extinction affect the early agnathans, gnathostomes, and ostracoderms?
- Early agnathans coexisted with early gnathostomes for approx. 50 mya
- Decline in ostracoderm diversity at end of Early Devonian (416–400 mya) may have been due to lowering of global sea levels
- Extinction of ostracoderms in Late Devonian (approx. 365 mya) occurred at same time as mass extinctions among many marine invertebrates
- Only ones that survived are lampreys and hagfishes
89
Cyclostomes
- Extant agnathans
| - round mouth
90
Describe what we mean by agnathans are a paraphyletic group, including the extinct jawless fishes.
- They are each other’s closest living relatives, but not necessarily closely related
- Lots of differences between them
- Branched off from each other a long time ago
91
A shared derived characters or Synapomorphy helps to identify what?
Presence of synapomorphy (shared derived characters) helps identify common ancestry
e.g., jaws show gnathostomes to be monophyletic group
92
Shared ancestral characters help to identify what?
- They don’t help
- Shared ancestral characters are uninformative
- Retention of jawlessness does not necessarily indicate monophyly
93
Which are more “primitive”? Lampreys, Ostracoderms or Hagfishes?
- Hagfishes and lampreys more “primitive” than ostracoderms
- Fossil record sparse
- Two fossil genera of each from approx. 360–300 mya
- Longer body today than in the past for Lampreys
94
How many mass extinctions have lampreys and hagfishes survived?
-Hagfishes and lampreys have survived through 4 mass extinctions
95
Hagfishes (Class Myxini; Order Myxiniformes): Facts
- Myx=slime
- Up to 75 species
- all marine, deep sea (why eyes have been lost)
- Also called “slime eels”
- Population depleted by fisheries use to demand for eel wallets
96
Hagfishes (Class Myxini; Order Myxiniformes): How are they in many respects “primitive?”
- Single semi-circular canal per side
- Rudimentary eyes (but secondarily lost) due to living in deep sea
- No vertebrae (but may have been secondarily lost)
- Body fluid isosmotic with sea water (does not osmoregulate, keeps salt and water concentrations the same as the sea water they live in)
- No heart innervation
- Open circulatory system and accessory hearts
97
Hagfishes (Class Myxini; Order Myxiniformes): Do their shared derived characters represent the ancestral vertebrate condition or are these derived specializations?
Today, studies are showing that their shared derived characters are actually specializations and not the case of ancestral vertebrate conditions.
98
Hagfishes (Class Myxini; Order Myxiniformes): Feeding
- Scavengers (earthworms of the deep, feed on dead fish in the sea)
- Greatly reduced eyes (no lens)
- Good sense of smell and touch
- Large folded tongue with ‘horny’ tooth plates (keratin=same structure as our fingernails are made)
- Single nostril for smell
- Able to tear off pieces of prey using knotted body for leverage (using tongue)
- Food engulfed in mucous membrane for digestion
99
Hagfishes (Class Myxini; Order Myxiniformes): Gills
- 1 to 15 external gill openings to let water out
- External opening displaced posteriorly
- Pouched gills with water intake through nostril
- Also capable of anaerobic and cutaneous respiration (while feeding)
100
Hagfishes (Class Myxini; Order Myxiniformes): Slime glands
- Also known as “slime eels”
- Mucus+protein threads
- Function of the slime? Probably for protection from predators and also protection for the skin
- Applications of the slime? Use of protein threads for surgical thread (doesn’t initiate immune response), used in cooking
- 70-200 pairs of slime pores
101
Hagfishes (Class Myxini; Order Myxiniformes): Reproduction
- Little known about reproduction
- Single gonad
- Likely external fertilization
- No obvious seasonality, so year round
- But highly female-biased sex ratios
- Some species hermaphroditic
- Produce few large eggs which appear to hatch directly into fully formed hagfishes, rather than larvae = Direct Development
102
Lampreys (Class Petromyzontida; Order Petromyzontiformes): Facts
- petro=stone, myzon=sucker
- Approx. 40 species in 10 genera
- Temperate regions of N and S hemispheres
- 18 species are parasitic on bony fishes
103
Lampreys (Class Petromyzontida; Order Petromyzontiformes): Characteristics
- Attach with large oral disk
- Horny teeth (keratin) on disk and tongue rasp hole in side of fish
- Oral gland secretes anticoagulants
- Blood rich and easily digested
- Generally do not kill host
104
Lampreys (Class Petromyzontida; Order Petromyzontiformes): Which characteristics of the lamprey are currently being studied for medical purposes?
- Spinal cord regeneration (only vertebrate who can do this)
- Iron loading
105
Arrange the following characters in order of their appearance in the chordates:
- dorsal fin
- jaws
- mineralized tissue
- notochord
- pectoral fins
- pharyngeal gill slits for respiration not filter feeding
1) The first: Notochord
2) Pharyngeal gill slits for respiration, not filter feeding
3) Dorsal fin
4) Mineralized tissue
5) Pectoral fins
6) Jaws
106
How do lampreys appear more “advanced” than hagfishes?
-have cartilaginous vertebral structures homologous with neural arches in gnathostomes
107
Which group were lampreys previously thought to be a sister taxon to? But recent evidence shows that they are actually a monophyletic group with which species?
- Were generally considered sister taxon to gnathostomes
- But, as mentioned, recent evidence that hagfishes with “long overlooked vertebral elements” and that hagfishes and lampreys do form monophyletic group
108
How are lamprey’s characteristics more derived than hagfishes?
- Two semicircular canals per side
- Heart innervated by parasympathetic nervous system (PNS)
- Well-developed kidneys and ability to osmoregulate
- One of the first vertebrate groups to invade fresh water
- Anadromous: species that reproduce in both fresh and salt water
- Well-developed eyes (in adults)
- Well-developed pineal gland (Important in seasonality for reproduction)
- Always seven pairs of gills
- Tidal ventilation (in adults, inefficient water comes out one opening and coming out through same opening, effective for eating and breathing separately) rather than flow-through (in larvae, other fish, water in mouth and out the gills)
- Velum prevents water from flowing out of respiratory tube into mouth
- Single nasal opening on top of head
109
Anadromous
Anadromous: species that reproduce in both fresh and salt water
110
What are lampreys called in German and why?
In German they are called Neunaugen=nine eyes (nine hole on one side)
111
What are the lamprey larvae called?
Ammocoetes
112
What are some characteristics of lamprey larvae?
- Indirect development
- Filter feeders in fresh water for 3-7 years
- Takes a long time for them to get very large since they are feeding on nutrient-poor dentritus
113
What is the lifecycle of the lamprey?
1) Larval stage burrowed in sediment
2) Metamorphosis
3) Downstream Migration
4) Parasitic feeding
5) Upstream Migration (against current)
6) Spawn an die (die at end of cycle)
114
Lampreys (Class Petromyzontida; Order Petromyzontiformes): Biology
• All lampreys spawn in fresh water
• Use oral disk for spawning
-Females produce many, small eggs
-Many of the parasitic species are anadromous
-Some parasitic in fresh water
-One freshwater species (Entosphenus minimus) approx. 70 mm at maturity
115
Why is the “Landlocked” Sea Lamprey present in the Great Lakes and why are they a concern? Control measures? Adaptations of lampreys to control measures? Newer control strategies?
-Most notorious (although many lamprey species highly valued)
-Invaded Upper Great Lakes with building of Welland Ship Canal in 1829
-Largely blamed for destruction of multibillion dollar commercial fishery
-Although likely exacerbated by overfishing
-Control measures include:
○ Barrier dams
○ Chemical lampricides
-But some rivers too large to treat
-And also toxic to native lamprey species
-Also, adaptations by lampreys:
○ Spawning in bays
○ Younger age at metamorphosis
○ Female-biased sex ratios
-Newer control strategies:
○ Sterile Male Release Technique
○ Disrupting migration or spawning using pheromones
116
Nonparasitic lampreys: Characteristics
- More than half species don’t feed at all as adults
- Only vertebrates with non-trophic adult stage
- Stop feeding at metamorphosis; spawn and die 6-9 months later
- Non-migratory= “brook lampreys”
- Nonparasitic lampreys in seven lamprey genera
- Recently derived from parasitic counterpart
- Lower fecundity but lower mortality
117
Nonparasitic lampreys: Lifecycle compared to the parasitic ones
* Non-parasitic lifecycle
1) Larval stage
2) Metamorphosis
3) Spawn and die
* Parasitic lifecycle
1) Larval stage burrowed in sediment
2) Metamorphosis
3) Downstream Migration
4) Parasitic feeding
5) Upstream Migration (against current)
6) Spawn an die (die at end of cycle)
118
How have the lampreys and hagfishes survived for so long?
Hagfishes:
- Deep sea, hasn’t changed over time very much
- Avoided upheaval in marine coastal areas
Lampreys:
- Generalists, extremely adaptable
- Migratory pheromones (where larvae currently are)
- Life history adaptability (become non-parasitic)
- Adaptations to sea lamprey control
119
Gnathostomata: Facts about origin of jaws
- Gnath = jaws
- First gnathostome fossils approx. 440 my old
- Evolution of jaws “perhaps the greatest of all advances in vertebrate history” (A.S. Romer)
- Allowed wide variety of feeding behaviours, especially with evolution of teeth and other manipulations
- Jaws=synapomorphy and monophyletic (Gnathostomata)
120
Draw a simple tree showing the relationship among the following taxa: Cephalochordates, conodonts, gnathostomes, hagfishes, lampreys, osteostracans and urochordates. Assume that the extant agnathans are monophyletic. Also indicate where the following traits first arose: cranium, dermal bone, mineralized tissue, pectoral fins, pelvic fins, jaws
Cephalochordates, Urochordates, *cranium, Hagfish (Myxini) and Lamprey (Petromyzontida), *mineralized tissue, Conodonts, *dermal bone, *pectoral fins, Osteostracans, *jaws, *pelvic fins, Gnathostomes
121
How is the origin of jaws and the evolution of gills related?
- Differences between jawless (pouched gills with gill arches external to gills) and jawed vertebrates (sheet gills with internal arches) originally suggested non- homology of branchial arches
- Originally suggested separate (independent) evolution
- Evidence that jaws evolved from anterior-most gill arches
- Branch=gill
122
What was argued by Mallatt in 1996?
Mallatt (1996) argued that ancestral vertebrate had both internal and external gill arches (and flow- through ventilation)
123
What can you say about the internal and external gill arches regarding the following:
A) hagfishes an lampreys
B)ancestral gnathostome
C) sharks
D) Bony fishes
The differences in gill arch position are produced by what?
A) In hagfishes and lampreys, external gill arches retained (better for tidal ventilation)
B) Ancestral gnathostome likely kept both internal and external, but with inner arches larger
C) Sharks have cartilaginous vestige of external arch
D) External arches completely absent in bony fishes
*Recent evidence that difference in gill arch position produced by switch in developmental timing
124
What are some other synonymous names for gill arches?
Pharyngeal arches=branchial arches=gill arches
125
Jaws evolved or derived from what?
General consensus now that jaw represents modification of anterior pair of pharyngeal arches (1st gill arch)
126
In gnathostomes, the first pharyngeal arch becomes what? Identify the two parts this structure.
In gnathostomes, 1st arch (mandibular arch; Lab 2) becomes jaw:
○ Palatoquadrate = roof of mouth, upper jaw
○ Meckel’s (or mandibular) cartilage = lower jaw
127
The 1st gill slit becomes what in sharks/rays and in tetrapods?
1st gill slit becomes:
Spiracle in sharks, rays
Eustachian tube in tetrapods
128
The 2nd gill arch becomes which structures?
2nd gill arch becomes hyoid arch, supporting function
129
How many pairs of gills do lampreys have compared to extant fishes?
* Lampreys with 7 pairs of gills
| * Most extant fishes with five pairs
130
What supports the “Evo-Devo” theory?
- That gnathostome jaws homologous with branchial arches, same embryonic origin
- During development, mandibular and hyoid arch develop in series with branchial arches
- All derived from neural crest
- Mandibular, hyoid, and branchial arch muscles all derived from head mesoderm
- Motor nerves innervate arches in series
- Same genes are expressed in the mandibular segments of lampreys and gnathostomes
131
What are the stages leading to the evolution of jaws?
1) first pharyngeal gill arch initially some distance behind mouth
2) Mallatt (1996) suggested transformation of 1st and 2nd branchial arches driven by increased need for ventilation
3) “Protojaw” initially respiratory in function. Stronger pumping action for suction of water into mouth.
4) Only later became used for feeding
6) Increased suction could lead to increased prey capture.
7) Later, with modifications to restrain struggling prey=teeth. *And gnathostome teeth apparently evolved after jaws
132
True or False? Jaws is a synapomorphy and Gnathostomes are monophyletic.
True
133
Gnathostomes: Synapomorphies besides jaws
1. Two sets of paired fins or limbs (but secondary loss in some)
- Mobile fins for movement in 3D space
- Fins apply pressure to water
- Better developed tail (caudal) fin increases surface area, giving more thrust during propulsion
- Median fins (unpaired dorsal, anal fins) control tendency to “roll” (rotate around the body axis) or “yaw” (swing left or right)
- Paired fins (pectoral and pelvic fins) control “pitch” (tilting up and down) and act as brakes
- Non-locomotory functions as well: Defense, Sensory and Visual signals
2. Three semicircular canals in each inner ear (3D orientation)
3. Two olfactory bulbs leading to two nostrils
4. Teeth on jaws (although absent from early gnathostomes)
- “Osteichthyes” with teeth embedded in jawbone
- Cartilaginous fishes with teeth formed in skin
134
Function of caudal fin in gnathostomes
Better developed tail (caudal) fin increases surface area, giving more thrust during propulsion (apply pressure to water)
135
Function of median fins in gnathostomes
Median fins (unpaired dorsal, anal fins) control tendency to “roll” (rotate around the body axis) or “yaw” (swing left or right)
136
Function of paired fins (pectoral and pelvic fins) in gnathostomes?
```
Paired fins (pectoral and pelvic fins) control “pitch” (tilting up and down) and act as brakes
*Unique to extant gnathostomes
```
137
Function of fins in general?
- Fins apply pressure to water for locomotion
| - Non-locomotory functions as well: Defense, Sensory and Visual signals
138
Where are the teeth in jaws of:
A) early gnathostomes
B) Osteichtyes
C) Cartilaginous fishes
A) teeth on jaws absent in early gnathostomes
B) “Osteichthyes” with teeth embedded in jawbone
C) Cartilaginous fishes with teeth formed in skin
139
Gnathostomes: Other trends (not synapomorphies) in structures found in this group
1. Elongated cranium with postorbital processes
- Protection, musculature for eyes
2. Progressively more complex vertebrae
- Neural and hemal arches
- Vertebral centrum
- Eventually replacing notochord as main support for musculature
3. Ribs
- Increased anchorage for axial muscles
- Respiration, protection of viscera
140
Early Gnathostomes: Extinct species
- Placoderms (“Plate skins”)
- “Stem gnathostome” (at base of the tree, don’t extend all the way to the crown of the tree)
- Many primitive traits relative to other gnathostomes: Most lacked true teeth and Primitive chondrocranium
- Probably offshoot of main lineage
- Early Silurian to end of Devonian (ca. 440–354 mya)
- Separate head and trunk shields linked by mobile joint
- large group known as Arthrodires (Arthro=“jointed” and dires = “neck”)
- Big (10 m), predatory
- Armour reduced in more derived forms
- Ancestral placoderms primarily marine, but many became adapted to fresh water
141
How is the aquatic environment different than air?
1) density
2) viscosity
3) oxygen content
4) heat capacity and conductivity
5) electrical conductivity
1. Density
• 800x more than air
• More support for animal’s body
• Largest vertebrates aquatic
2. Viscosity
• 55x more viscous than air
• Requires streamlining and efficient gill ventilation
3. Oxygen content
• Five to twenty-five percent air’s concentration
4. Heat capacity and conductivity
• Specific heat of water 3500X higher than air
• Conducts heat 24X faster
• Water temperatures more stable than air but “whisks” heat away from body
5. Electrical conductivity
• Air can’t conduct electricity in voltages generated by animals
• But water can
142
True or false? The general consensus is that the Gnathostome jaw evolved from the first pharyngeal arch of agnathan vertebrates, and the second arch became the hyoid arch supporting the jaw.
True
143
True or false? The first gill slit became the spiracle in sharks, and the second gill slit became the Eustachian tube in tetrapods.
False: 1st gill slit became Eustachian tube in tetrapods and spiracle in sharks
144
True or false? Jon Mallatt suggested that these modifications to the first gill slits would have immediately increased the efficiency of prey capture.
False: increase efficiency in ventilation
145
True or false? The homology of agnathan and gnathostome gills was not immediately apparent because extant agnathans have pouched gills with internal gill arches whereas the extant jawed vertebrates have sheet gills with external arches.
False: agnathans don’t have internal but external gill arches
146
How do many fish obtain oxygen in the water?
- gills allow for flow-through ventilation that is very efficient
- Gills with high surface area
- Gill filaments highly vascularized
147
Who uses tidal or flow-through ventilation to obtain oxygen in water?
- Lampreys (adults, not larvae)
- Not very efficient method
- Useful due to feeding method
- NOT BUCCAL PUMPING
- water is taken in by the nostrils and passes over the gills
148
Facultative vs Obligate
Facultative=can do something, but don’t have to
| Obligate=Have to
149
Buccal pumping vs ram ventilation
- Ventilation: to move water over the gills
- Buccal pumping: most fish use this, buccal=mouth, water comes in through mouth and forced into mouth and over gills
- Facultative ram ventilation: swim with mouth open and forces water over the gills, facultative = can do it but don’t have to
- Obligate ram ventilation: obligate=have to, sharks can drown if prevented from swimming (asphyxiate)
150
How do lampreys and hagfishes take in oxygen in the water?
Lampreys use flow-through or tidal ventilation=taking into nostrils and then water over gills (not buccal pumping!)
Hagfish do cutaneous respiration (take in oxygen through the skin)
151
Which accessory surfaces can supplement gill respiration?
- Enlarged lips
- Gulping air
- Vascularized chambers in head (betas)
152
Why are electric eels obligatory air breathers?
-need to be able to access the surface to breath air, not enough oxygen through gills so need supplement
153
How did lungs originate and where are they located?
- Lungs: out pocketings of pharyngeal region of digestive tract
- Ventral to digestive system (lungfishes, bichirs, tetrapods) = ancestral
- Dorsal (gars, teleosts), involved in buoyancy
- Can have increased surface area for gas exchange
- Lungs originate in fish, preceded evolution of tetrapods by millions of years
154
What is another name for lungs?
Swim bladder (they are homologous and are the same structure) in fish
155
Lungs/swim bladder use in fish?
- Smooth walls and interwoven collagen fibers impermeable to gas
- increased surface area for gas exchange
- Approx. 5% body volume in marine fish; 7% Freshwater fish
- For buoyancy
- Adjust gas volume to change depth
156
What is the difference in size of the swim bladder in salt vs freshwater fish? Why does this difference exist?
- Approx. 5% body volume in marine fish; 7% Freshwater fish
- Salt water naturally gives more buoyancy than fresh water that’s why there is a difference so marine fish need only a smaller swim bladder
157
Physostomous vs Physoclistous fish
• Physostomous fish (“bladder + mouth”)
○ With pneumatic duct connecting gut and swim bladder
○ Gulp air and push into swim bladder
○ e.g., salmon, minnows, goldfish
• Physoclistous fish (“bladder + closed”)
○ Gas gland on ventral floor of swim bladder (rete mirabile=miraculous net changes pH of blood)
○ Secretes gas from blood
○ In more derived fish
○ But slower
158
How do cartilaginous fish, lampreys and hagfishes increase their buoyancy?
Cartilaginous fishes, lampreys and hagfishes:
○ Without swim bladders
○ High oil content in liver (squalene) increases buoyancy
○ Pectoral fins provide lift
159
How do deep sea teleosts increase buoyancy? Why is it better to not have a swim bladder in the deep sea?
- Also with oil or fat deposits that increase buoyancy
- Reduced skeleton
- Loss of swim bladder in some
- Very energetically expensive to maintain the swim bladder
- Deep sea has high pressure, so the swim bladder would remain compressed all the time
160
Sensory systems in water: Vision
- In general, more limited sight in water
- Also, differences in way image is focused on retina
- Cornea in terrestrial vertebrates
- Spherical lens with high refractive index in fish
- Water doesn’t bend in spherical lens of fish since refractive index is the same as water, whereas the light in air is bent in cornea for terrestrial animals (refractive indexe of cornea is higher than air)
161
Sensory systems in water: Taste and Smell
- Taste buds in mouth, around head, anterior fins
- Can be very acute
- Food and other forms of communication
- Walleye can taste the lure without ever opening its mouth (taste buds all over the place). Imagine tasting a chocolate sundae with your whole body.
- Water soluble molecules
162
Sensory systems in water: Lateral Line
- Detects water displacement
- Fishes, amphibian larvae and aquatic adults
- Only water dense enough to stimulate neuromast organs
- Neuromast organs (hair cells and a nerve underneath that detects the movement) on head and body stimulated by water movement
- Prey detection, turbulence in schooling fishes (following along behind other fish)
163
Neuromast organs
hair cells and a nerve underneath that detects the movement on head and body stimulated by water movement
164
Sensory systems in water: Electroreception
- Saltwater conducts electricity better than Freshwater
- Sharks can detect electrical activity from muscle contractions of prey using ampullae of Lorenzini on head of sharks and on pectoral fins of rays
- Can also produce electric discharges using modified muscle tissue
- For use as weapon (e.g., torpedo ray, electric catfish, electric eel)
- For electrolocation and social communication (e.g., knifefish, elephant fish)
- Similar to echolocation
- Produce weak electric fields and how it bounces back lets them know what’s in the vicinity
165
True or false? Water is 800X more dense than air.
True
166
True or false? On average, saltwater fishes have larger swim bladders than freshwater fishes.
False. Freshwater fishes have larger swim bladders than saltwater, because salt water is more buoyant so don’t need a larger swim bladder (just wasting energy).
167
True or False? A physostomous fish lacks a connection between its swim bladder and its mouth.
False. Physostomous fish do have a connection between the swim bladder and its mouth.
168
True or false? Tidal ventilation is more efficient than flow-through ventilation.
False. Flow-through ventilation is more efficient than tidal ventilation.
169
True or false? Great white sharks can drown (asphyxiate) if denied access to the surface; electric eels can drown if prevented from swimming.
False. Great white sharks can drown (asphyxiate) if prevented from swimming; electric eels can drown if denied access to the surface.
170
True or false? It is hard to be an ectotherm (cold blooded) in water because water conducts heat 24X faster than air.
False. It’s harder to be an endotherm in water because water conducts heat 24X faster than air.
171
Ectothermic vs Endothermic
Ectothermic: heat comes from outside of organism
Endothermic: heat produced inside the organism, hard to control body temperature in water
172
Countercurrent heat exchangers
retain heat produced by swimming muscles
173
Which aquatic vertebrates regulate ionic concentration of body fluids?
Hagfishes are the only ones that don’t
| Their body functions at same concentration as sea water
174
Which organisms are hyperosmotic? What does this mean?
- Freshwater fishes and amphibians
- Water will flow into organisms by osmosis
- Ions diffuse out
- Very dilute medium
175
Are scales or gills more permeable to water and ions?
Body surface of fish (scales) with low permeability to water and ions, but gills are permeable
176
What are consequences of hyperosmotic organisms?
- Do not drink
- Produce dilute urine (to get rid of excess water, but constantly losing ions too)
- Salts actively resorbed in kidney (to reduce amount of ions lost)
- Chloride cells in gills for active transport in of Cl-
- Salts from foods
177
Which parts of the freshwater amphibians are involved in ion uptake?
In FW amphibians, whole body surface involved in ion uptake
178
Which organisms are hyposmotic? What does this mean?
Saltwater Teleosts
| Water loss and ions will diffuse in
179
What are some consequences of hyposmotic organisms?
- Drink sea water
- Concentrated urine (in order to retain water)
- Chloride cells in gills pump Cl ions out
180
Marine cartilaginous fishes regulate ions and body fluids how?
- Use urea and other N compounds to make blood slightly hyperosmotic
- Kidneys get rid of excess water
- Gills low ion permeability
- Ion secretion from rectal gland
- Lower salt concentration in blood but osmolarity increased
- Water and ion absorption through gills
181
Class Chondrichthyes (Cartilaginous fishes): Synapomorphy
Pelvic claspers in males of all species (internal fertilization)
182
Class Chondrichthyes (cartilaginous fishes): Other characteristics (not synapomorphies)
- Cartilaginous skeleton
- Although may show calcification of endoskeleton
- bone in teeth and scales (placoid)
- Lipid-filled liver and high blood urea concentration (Important for osmoregulation)
183
Class Chondrichthyes (cartilaginous fishes): 2 extant subclasses
1. Holocephali
○ Ratfishes, chimeras (extant)
2. Elasmobranchii
○ Stem elasmobranchs and hybodonts (extinct)
○ Neoselachii (sharks, skates, rays; extant)
184
Class Chondrichthyes (cartilaginous fishes): Extinct Group: Stem Chondrichthyes (Cladoselache): Facts
- Branched off before split between subclasses
| - Look like primitive sharks
185
Class Chondrichthyes (cartilaginous fishes): Extinct Groups?
1. Stem Chondrichthyes (e.g., Cladoselache, Fig. 5-3a)
| 2. Extinct Elasmobranchs
186
Class Chondrichthyes (cartilaginous fishes): Extinct Group: Stem Chondrichthyes (Cladoselache): Characteristics
i. Terminal mouth (vs subterminal mouth seen in extant sharks)
ii. Amphistylic upper jaw suspension (Amphi=two, Upper jaw with two sites of suspension, Palatoquadrate attached to chodrocranium by ligaments)
iii. Broad-based pectoral fin
iv. Heterocercal caudal fin (notochord or ventral column follows into the upper lobe of the tail, so likely rapid pelagic feeders)
v. Only notochord for support (not replaced by vertebrae, unconstricted notochord)
vi. Placoid scale distribution limited to fins, eye area, mouth behind teeth
vii. 3-cusped teeth, similar in structure to placoid scales (teeth and scales are homologous)
viii. Unique tooth replacement pattern in chondrichthyans = Tooth whorl (fresh teeth come in to replace old ones like a conveyor belt)
187
Why are teeth said to be homologous to scales?
Teeth evolve from placoid scales which grew up and over surface of mouth
188
Amphistylic vs Hyolistic jaw vs Autostylic
Amphistylic: Amphi=two, Upper jaw with two sites of suspension, Palatoquadrate attached to chodrocranium by ligaments
Hyostylic jaw: Elastic ligament attaches anterior end of Palatoquadrate to braincase, Posterior attachment can rotate, Jaw can drop below snout = very flexible
Autostylic jaw: Palatoquadrate fused to cranium
189
Tooth whorl
fresh teeth come in to replace old ones like a conveyor belt
190
Class Chondrichthyes (cartilaginous fishes): Extinct Group: Elasmobranchs: Facts
- Closest relatives to the Chondrichthyes
- After split between subclasses
- Stem elasmobranchs and Hybontia (Fig. 5.1)
- Elasmobranch=plate+gill
- First appeared in Paleozoic
- Flourished until late Cretaceous
191
Class Chondrichthyes (cartilaginous fishes): Extinct Group: Elasmobranchs: Characteristics
e. g., Hybodus (Fig. 5-5) is the model
- Much like modern sharks except mouth terminal
- Paired fins more flexible (pectoral fin) than Cladoselache, with narrower base
- Flexible Ceratotrichia
- Asymmetrical Heterocercal tail
- Anal fin (none in Cladoselache)
- Complete set of hemal arches (none in Cladoselache)
- Well-developed ribs (vs Cladoselache)
- heterodont teeth (Piercing teeth at front, crushing teeth in back)
- Similar to dentition in living horn sharks, Heterodontus
192
Heterodont teeth
Piercing teeth at front, crushing teeth in back
193
Class Chondrichthyes (cartilaginous fishes): Extant Groups: 2 subclasses?
1. Holocephali (contains ratfishes, chimaeras)
2. Elasmobranchii (contains Neoselachii)
* don’t need to know divisions, only classes and subclasses
* just know that Neoselchi is in the Elasmobranchii
194
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Synapomorphies
- Sharks, Skates, Rays
- Multiple gill openings (elasmobranch = plate + gill)
- Neoselachii [division] = living elasmobranchs
- Main difference between living and stem elasmobranchs is mouth position and jaw suspension
- Subterminal mouth
- Hyostylic jaw (Elastic ligament attaches anterior end of Palatoquadrate to braincase, Posterior attachment can rotate, Jaw can drop below snout = very flexible)
195
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Other characteristics
- Solid, calcified vertebrae (Constrict and, in some species, replace the notochord)
- Thicker, more complex enamel-like material on teeth (Highly mineralized, why sharks are highly fossilized)
- More flexible placoid scales (Reduces turbulence and increases swimming efficiency , Still protective)
196
What is the Speedo “Fastskin?”
Speedo “Fastskin” inspired by shark skin
- Swimsuit (full-body) with ridges emulating shark skin
- World records in swimming, but then banned in Olympics in 2010
197
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Subdivision Selachii
- Sometimes called Pleurotremata (side + hole)
- 5–7 gills on side of head
- At least 2 lineages: Squalomorphi and Galeomorphi *just know its a subdivision of sharks
- 550 extant species=more diverse than lampreys and hagfishes
198
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Subdivision Selachii: Squalomorphi
- ca. 160 spp.
- More “primitive” in general anatomy (Especially smaller brain size)
- Cold, deep water
- e.g.,dogfish sharks, cookie-cutter shark, frill shark (with unconstricted notochord, mouth nearly terminal), cow sharks, saw sharks (different from sawfish!), angel sharks
- Counter illumination breaks up fish’s shadow when seen from below
199
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Subdivision Selachii: Galeomorphi
- More familiar sharks than Squalomorphi
- ca. 390 spp.
- Dominant carnivores in shallow, warm regions
- e.g., great white and mako sharks, thresher sharks (like the scythe used to thresh wheat), goblin shark (>1300m deep), basking shark (2nd largest extant fish species, plankton feeder, in same order as great white shark)
- e.g., bull shark and Ganges shark (can osmoregulate in freshwater)
- E.g. hammerhead sharks, horn sharks
- e.g., whale shark (largest extant fish species) , carpet sharks
200
Why are sharks highly fossilized?
- Thicker, more complex enamel-like material on teeth
| - Highly mineralized teeth, why sharks are highly fossilized
201
Why is more flexible placoid scales advantageous?
- Reduces turbulence and increases swimming efficiency
| - Still protective
202
Which are the largest and second largest extant fish species?
1) whale shark
2) basking shark
* Both in the Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Subdivision Selachii: Galeomorphi
203
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Skates and Rays (Batoidea): Characteristics
- Or sometimes called Hypotremata (below + hole)
- Gills on ventral surface
- Spiracle dorsal
- ca. 640 extant species *on exam know approximation (1200 extant elasmobranchs)
- Marine (some freshwater)
- Very flat, with pectoral fins fused to head, no anal fin
- Reduced placoid scales (synapomorphy of their group)
- Most are bottom dwellers
- Feed on shelled invertebrates
204
Most skates and rays are bottom dwellers, and filter feeders, feeding on shelled invertebrates, but what is an exception to this?
- Manta ray is an open water predator
| - has scoop-like appendages on the head to direct plankton into the mouth
205
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Skates and Rays (Batoidea): Examples
- Eagle rays and stingrays have whiplike tails, fins replaced by more than one barb, and have poisonous spines
- sawfish
- electric rays: Rounded pectoral disc, Soft, flabby body, Up to 220V
- guitarfishes
206
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Elasmobranchii: Sharks characteristics: Sensory systems and prey detection
- Acute sense of smell (drop of blood in 94L water) allows to detect prey from a large distance
- Electroreception and geomagnetism: Ampullae of Lorenzini ex) Hammerhead shark can detect 1/2 billionth V from prey!
- Good vision at low light intensity
- Some with nictitating membrane (the third eyelid, the pink in our eye is a remnant of this), protects eye from injury during hunting prey when gets very close
- Vibrations and turbulence: Lateral line and inner ear, Better directionality than smell
- Therefore, big brain for processing all sensory information
207
Which sensory systems in sharks are the most important based on the distance between them and their prey?
```
Furthest to closest
1) smell
2) hearing
3) vibrations and turbulence
4) vision
Five) ampullae of Lorenzini
6) taste
```
208
How do sharks (Elasmobranchii) reproduce?
- Internal fertilization
- Males with claspers
- Sometimes barbs, hooks and spines
- Females with very thick skin!
- Small number of large offspring
- Direct development
209
What are the two reproductive methods of sharks (Elasmobranchii)?
1. Oviparity
- Young hatch from egg outside mother’s body
- Nutrition from yolk (lecithotrophy nutrition) for 6 –15 months
- Case produced by nidimental gland
- e.g., horn shark, skates
2. Viviparity most common state in extant elasmobranchs
- Eggs hatch in oviduct; live birth
- May be no nutrition from mother besides yolk (lecithotrophic)
- More protection inside the mother
- Or may be matrotrophic (nutrition from mother):
1) "intrauterine cannibalism"
- Great white shark, tiger shark, mako shark
- largest sibling eats its smaller siblings
2) nutrition from uterine secretions or placenta
- Hammerhead shark
- No parental care since lots of energy is already expended providing additional nutrition
210
Matrotrophic meaning and the two methods?
- Nutrition from mother
1) "intrauterine cannibalism"
- Great white shark, tiger shark, mako shark
- largest sibling eats its smaller siblings
2) nutrition from uterine secretions or placenta
- Hammerhead shark
- No parental care since lots of energy is already expended providing additional nutrition
211
Class Chondrichthyes (cartilaginous fishes): Extant Groups: Subclass Holocephali: Facts and characteristics
- ratfishes, chimaeras
- Diverged from elasmobranchs >400 mya
- ca. 50 extant species vs 1200 extant elasmobranchs
- Gill arches covered by soft operculum
- Single gill opening on each side gives head undivided appearance (holocephali = whole + head)
- Long tail
- Upper jaw fused to cranium (holostyly)
- Crushing tooth plates
- Deep sea but breed in shallow water
- Males with spiny clasper on head
- Large, horny-shelled eggs
212
What would make Osteichthyes a paraphyletic group?
If you exclude the tetrapods
213
Clade Osteichthyes is separated into what 2 groups?
-All remaining vertebrates belong to Clade Osteichthyes (“Bony fishes”)
-Includes tetrapods
-Osteichthyes (“Bony fishes”) are paraphyletic without tetrapods
A) Sarcopterygii (lobe-finned fishes and tetrapods)
B) Actinopterygii (ray-finned fishes)
*although both with bony rays (lepidotrichia)
214
Class Osteichthyes: Synapomorphies (including tetrapods)
A) Endochondral bone
-Dermal and perichondral bone also retained
-Develops in and replaces cartilage
B) Dermal, marginal tooth-bearing bones
-Maxilla, premaxilla, dentary
-Overlay and replace primary jaws formed by PQ and MC
215
Class Osteichthyes: Synapomorphies (excluding tetrapods=paraphyletic)
C) Other dermal bones on roof of mouth and forming a bony operculum (gill covering) and branchiostegal rays (protect ventral surface of the gills)
D) Gas bladder (swim bladder/lungs)
-Important in buoyancy and gas exchange
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What does this Latin or Greek word mean and where have we seen them? Branch
Branch: gill, Elasmobranch, branchiostegal rays
217
What does this Latin or Greek word mean and where have we seen them? Cephalo
Cephalo: Head, Cephalochorates
218
What does this Latin or Greek word mean and where have we seen them? Chondr
Chondr: Cartilage, Chondrichthyes, perichondral bone
219
What does this Latin or Greek word mean and where have we seen them? Derm
Derm: Skin, Ostracoderm, dermal bone
220
What does this Latin or Greek word mean and where have we seen them? Gnath
Gnath: jaw, Agnathan, Gnathostom
221
What does this Latin or Greek word mean and where have we seen them? ichthyes
Ichthyes: Fish, Chondrichthyes
222
What does this Latin or Greek word mean and where have we seen them? Oste
Oste: Bone, Osteichthyes
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What does this Latin or Greek word mean and where have we seen them? Physo
Physo: Bladder, Physostomous, physoclistous
224
What does this Latin or Greek word mean and where have we seen them? Pter
Pter: Fin, Sarcopterygii, Actinopterygii
225
What does this Latin or Greek word mean and where have we seen them? Sarco
Sarco: Flesh, Sarcopterygii
226
What does this Latin or Greek word mean and where have we seen them? Stome
Stome: Mouth, Protostome, deuterostome, gnathostome
227
What does this Latin or Greek word mean and where have we seen them? Uro
Uro: Tail, Urochordata
228
Clade Osteichthyes: Class Sarcopterygii
- Sarco=flesh
- fleshy finned or lobe finned fishes
- Paired fins fleshy, with bony central axis
- Only four genera (8 spp.) of extant sarcopterygian fishes
- Gave rise to Tetrapods
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Clade Osteichthyes: Class Sarcopterygii: Dipnoi (Lungfishes): Facts
- Early dipnoans marine, widespread
- At least 50 genera in fossil record
- Now exclusively freshwater
- Only three genera (6 sp.) extant, each on single continent in Southern Hemisphere
230
Clade Osteichthyes: Class Sarcopterygii: Dipnoi (Lungfishes): Characteristics
- Autostylic jaw suspension (PQ fused to cranium)
- Skeleton mostly cartilage, although tooth plates heavily mineralized
- Connection between swim bladder and esophagus is ventral (ancestral)
231
Clade Osteichthyes: Class Sarcopterygii: Dipnoi (Lungfishes): South American lungfish (Lepidosiren paradoxa)
South American lungfish, Lepidosiren paradoxa:
- First discovered in 1830s, did not think it was a fish, but an amphibian
- Special pulmonary circulation, partially divided heart
- External gills when newly hatched, like larval stage of amphibians
- Fin rays are lacking
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Clade Osteichthyes: Class Sarcopterygii: Dipnoi (Lungfishes): African lungfish (Protopterus annectens)
African lungfish (Protopterus annectens):
- 4 spp.
- Long filamentous fins
- Gills weakly developed
- Paired lungs
- Obligate air breathers
- Males of South American lungfish with vascularized extensions on pelvic fins during breeding season
233
Clade Osteichthyes: Class Sarcopterygii: Dipnoi (Lungfishes): Australian lungfish
Australian lungfish:
- Oldest morphological species, looks like fossilized lungfishes millions of years ago
- Uses gills almost exclusively
- More like fossil lungfishes
- Simple, unpaired lung
234
Clade Osteichthyes: Class Sarcopterygii: Dipnoi (Lungfishes): Estivation in lungfishes
- Happens in the summer, during a very dry season = desiccation, so go into this state (like hibernation in the winter time) to withstand the dry conditions
- Induced by heat or desiccation
- Burrow in mud
- Mucus forms protective envelope
- Slow metabolism to 1/60th normal rate
- Some revived after 4 years
235
Clade Osteichthyes: Class Sarcopterygii: Actinistia (Coelacanths): Facts
- Relatively unchanged since Late Devonian
- Mostly marine
- Fossils not found after Cretaceous (65 mya)
- But “living fossil” discovered in 1938
- Found in deep waters
236
Clade Osteichthyes: Class Sarcopterygii: Actinistia (Coelacanths): Found after thought to be extinct
- Caught in Indian Ocean by African fisherman, off mouth of Chalumna River
- Curator Marjorie Courtenay-Latimer took fish to taxidermist to preserve it
- Professor J.L.B. Smith (on holidays, boss)
- Latimeria chalumnae
- 1952: second specimen found in Comoros
- 1998: another species 10,000 km east of Comoros
237
Clade Osteichthyes: Class Sarcopterygii: Actinistia (Coelacanths): Characteristics
- Swim bladder filled with fat, ossified walls
- Predatory on fish, squid at night
- Curious rostral organ to find prey
- Lobed fins
- Nocturnal
- Reproduction Viviparous
- 13-month gestation period 5–25 “pups” at a time
- Must have internal fertilization
- Strange combination of primitive and derived characteristics
- e.g., urea for osmoregulation
- e.g., movement of paired appendages in same sequence as tetrapods
238
Clade Osteichthyes: Class Actinopterygii
-Fins supported by parallel bony rays (lepidotrichia), which are webbed with thin tissue
1. Subclass Cladistia:
Polypteriformes (bichirs and ropefish)
2. Subclass Chondrostei:
Acipenseriformes (sturgeons and paddlefishes)
3. Subclass Neopterygii:
1. Gars [Lepisosteiformes]
2. Amiiformes(bowfin) “Holosteans”
3. Teleostei: >28,000 species, >40 orders
239
Clade Osteichthyes: Class Actinopterygii: Subclass Cladistia: Facts and characteristics
* Only extant order Polypteriformes
* 12–16 spp. of bichirs (Fig. 6-7a) and ropefish (Africa)
* Numerous dorsal finlets (“many fins”)
* Well-ossified skeleton
* Heavy, interlocking ganoid scales
* Predatory in freshwater
* Reedfish: can survive out of water for about 1 hour
240
Clade Osteichthyes: Class Actinopterygii: Subclass Cladistia: Primitive features
- Heterocercal tail
- Ventrally placed lungs like lungfishes, tetrapods
- Plesiomorphic condition
- Obligate air breathers
- Spiracle
- Spiral valve in intestine
- Pectoral fins look lobe-like but NOT a lobe-finned fish
- Radials extend beyond body wall
* All Remaining Actinopterygii have a lung or swim bladder connects dorsally to foregut
241
Clade Osteichthyes: Class Actinopterygii: Subclass Chondrostei–Acipenseriformes: Facts and characteristics
-Sturgeons and paddlefishes
-“Cartilaginous bony fishes”
-secondary loss of endochondral bone (especially in paddlefishes)
-Reduction in scales (‘scutes’ in sturgeons)
-Both characterized by:
○ Spiracles
○ Spiral intestinal valve
○ Heterocercal tail
○ Electroreceptors
○ Lack of vertebral centra (i.e., unconstricted notochord)
242
Clade Osteichthyes: Class Actinopterygii: Subclass Chondrostei–Acipenseriformes: Sturgeons
- ca. 25 spp.
- Large (1-6 m) benthic fish
- Larger in salt water than freshwater ones
- Suction feeders with protrusible jaws, barbels (helps to find prey in the mud)
- Freshwater and anadromous (go to sea, but reproduce in freshwater)
- Northern Hemisphere only
- e.g., lake sturgeon in Manitoba (in Lake Winnipeg and the Assiniboine and Red rivers)
- Severely depleted in most parts of range
- Valued for rich flesh and caviar
- Especially from white Beluga sturgeon from Russia
- Up to 9m, fifteen hundred kg
- Large specimens may be 100 years old and carry more than 7 million eggs
- Up to $8000 per kg!
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Clade Osteichthyes: Class Actinopterygii: Subclass Chondrostei–Acipenseriformes: Paddlefishes
- 2 spp. (American and Chinese Paddlefish)
- Up to 2 m in length
- Long, flat rostrum
- Innervated with ampullary organs for electroreception
- American paddlefish in Mississippi River valley
- Filter feeders
- Chinese paddlefish in Yangtze River valley
- Feeds on fish
- May be extinct!
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Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii
-Modern bony fishes (“new fins”)
-Locomotory specializations=most with homocercal tail
-Very diverse group
○ Chondrosteans = Cartilagnous bony fishes
○ Holosteans=Wholly or Entirely bony fishes
○ Teleosteans=Final bony fishes
245
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Gars facts
- 7 spp. gars or “garpikes”
- Eastern North America from Great Lakes region to Costa Rica, with one species reaching Cuba
- Fresh or brackish waters
- Alligator gar (up to 3m) may enter salt water
246
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Gars primitive characteristics
- Thick ganoid scales (Lepisosteus=bony scales)
- Spiral valve in intestine
- Abbreviate Heterocercal tail
247
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Gars derived characteristics
- Vertebrae with centra
- Elongate body, jaws, teeth
- Note that nostrils at tip of snout Vs Pike nostrils are in front of the eyes
248
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Amiiformes (“Holosteans”), Bowfin
Bowfin (Amia calva)
- Predators
- Not valued as sport or food fish
- Although some use eggs as caviar
- Bad reputation for feeding on other fish
- Has an ocellus
249
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Amiiformes (“Holosteans”), facts
- Diverse group of fossil taxa (in Europe, Asia, NA)
- Single extant species, Amia calva in family Amiidae= Bowfin (Amia calva)
- Restricted to freshwater in eastern NA
- Up to 1 m long
- predators
- mix of primitive and derived characters
- Lives in warm, shallow water
250
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Amiiformes (“Holosteans”), characteristics
- Mix of primitive and derived characters
- Gular plate, abbreviate heterocercal tail
- But cycloid scales
- And shares key features of jaw operation with teleosts
- Gas bladder important in aerial respiration (Divided by internal septa)
- Males construct and guard nest, care for young after hatching (Sometimes broods young in their mouths)
251
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, number of species
>28700 species and >40 orders
252
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, jaw adaptations
- Protrusible jaws evolved independently 3-4x in teleosts
- Rapid and powerful suction
- Rapid extension of grasping margins of the jaws
253
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, pharyngeal teeth adaptations
- Fusion of tooth plates to one another and gill arches
- Evolved independently in several groups
- Grasping primary jaws + second pharyngeal jaws
- Teeth can be found in throat, jaw, cheeks, mouth
- Important in minnows and suckers for herbivory
- Primary jaws protrusible but toothless
- Grab food quick and then secondarily eat the prey slowly
- Moray eel: pharyngeal jaws can extend into mouth and pull prey into throat
254
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, fin specializations
- Flexible homocercal tail
- Along with swim bladder, allows fish to swim horizontally without using paired fins
- Paired fins thus more flexible and diverse in shape, size, position
- Used for other activities (e.g., defence like the lionfish that has spines associated with pectoral fins, food gathering, courtship, sound production, walking, flying)
255
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, Osteoglossomorpha (“Bony Tongues”)
- Most primitive living teleosts
- Approx. 220 species
- Mostly in tropical waters
- e.g., arowana, arapaima in Amazon, African elephant fishes (Weak electric signals for communication and orientation, Large cerebellum), Mooneye and goldeye (In Manitoba, Only temperate species remaining)
256
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, Elopomorpha, facts
- ca. 850 spp.
- All with indirect development
- The eels
- Leptocephalus larvae
- e.g., American eel and European eel
- NOT a lamprey
- Includes moray eels And gulper eels
- Deep sea
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Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, Elopomorpha, Characteristics
-Catadromous (opposite of anadromous = spawn in freshwater, and adults go to sea water)=Larvae start in sea water then Larvae go into freshwater
-Spawn in Sargasso Sea
-Larvae drift in currents, reach continental margins, transform, ascend rivers
-Some are bioluminescent
-Large jaws and big stomach (to accommodate for anything you find
-Secondary loss since resources are limited in deep sea:
□ Opercular bones
□ Ribs
□ Scales
□ Pelvic fins
□ Swim bladder
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Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, Ostarioclupeomorpha
- ca. 360 spp.
- herring, anchovies, sardines, shad
- Filter feeders
- Mostly marine schooling fishes
- Plus ca. 8000 spp. ostariophysans (ostariophysi = “bone + bladder”)
- Dominant (80 percent) freshwater fishes
- e.g., piranhas, neon tetras, blind cavefishes, catfishes, carps and minnows (Cypriniformes)
- Minnows with protrusible jaws vs. piranhas
- Pharyngeal teeth act as second jaws
- Success also attributed to Weberian apparatus
- Bones connect swim bladder to inner ear
- Enhances hearing
259
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, Euteleostei
○ >17,000 spp.
| ○ True ultimate bony fishes
260
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, Euteleostei, Protacanthopterygii
- pro=first
- ca. 360 spp.
- Many shared ancestral characters:
- Physostomous (retain connection with swim bladder)
- Pelvic fins in abdominal position
- Cycloid scales
- Jaws not protrusible
- Most have adipose fin
- Probably paraphyletic
- e.g., pikes, smelts, capelin, salmon, trout, whitefish, grayling
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Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, Euteleostei, Paracanthopterygii
-para=near or beside
- > 1340 spp.
-Predominantly marine fishes
-Derived features in most paracanthopterygians:
□ Physoclistous (no connection with swim bladder)
□ Pelvic fins in thoracic or jugular position
□ Ctenoid scales
□ Protractile premaxilla
□ Spines on dorsal, anal, and sometimes pelvic fins
□ Reduced number of pelvic and caudal fin rays
-May be paraphyletic
-e.g., cavefishes, anglerfishes (Modified dorsal fin spine looks like a fishing lure, Something dangles at end of the spine to lure its prey, Sexual Dimorphism=Different in size and shape, Female larger than male,Male is attached to her, blood stream attached to her), cods (Thoracic pelvic fins)
262
Clade Osteichthyes: Class Actinopterygii: Subclass Neopterygii: Teleostei, Euteleostei, Acanthopterygii
- spiny fins
- ca. 14,800 spp.
- Pelvic fin spines (as well as on dorsal, anal fins)
- Pelvic fins, if present, thoracic or jugular
- Pectoral fins high on body
- Physoclistous or swim bladder absent
- Very diverse
- e.g., flying fishes, guppies and other livebearers, sticklebacks, seahorses, and pipefishes, pufferfishes (have strong toxin, delicacy in Japan, many people ie when not cooked properly),Seahorse (male has a brood pouch), flatfishes
- >13,000 spp. in single order, Perciformes
- e.g., sunfishes, perches, cichlids, tunas, billfishes, butterflyfishes, marine angelfishes, parrotfishes, wrasses, remoras (“sharksuckers”)
263
Which Class is the most diverse than any other vertebrate group?
Actinopterygians more diverse than in any other vertebrate group
264
Teleost Adaptations in reproduction: Oviparity
- most are oviparous
| - 2 types: pelagic spawners and benthic (demersal) spawners
265
Teleost Adaptations in reproduction: Oviparity: Pelagic spawners
- dispersal of eggs in the water, released into the open water
- Especially marine fish (tuna, sardines, cod, flounder, coral reef fish)
- Numerous small buoyant (planktonic) eggs
- A lot may be eaten by predators
- Indirect development=Pass through larval stage
- High mortality but may have advantages:
* Move eggs away from predators in adult habitat
* Move larvae to highly productive pelagic environment
* Allow dispersal to new habitats
* Prevents overpopulation
- Sometimes called “chuck it and chance it”
- Not all marine fish pelagic spawners (Capelin, California Grunion=Beach spawners)
266
Teleost Adaptations in reproduction: Oviparity: Benthic (Demersal) Spawners
- More common in freshwater teleosts
- Some with sticky eggs on vegetation or hidden in nests or crevices or other organisms (lay eggs in muscles)
- e.g., pike, carp, salmon, bitterling
- No parental care
267
Teleost Adaptations in reproduction: Oviparity: Parental care
- *haven’t seen parental care until now!
- Many species guard eggs and/or embryos
- Males may guard nests
- e.g., clownfish under protection of anemone symbiotic relationship with host, sunfishes, sticklebacks
- Parents may carry eggs or young In gill cavities (e.g., cavefish),On skin patches or pouches (e.g., pipefishes, male seahorses carries eggs in pouch laid by female), In mouth (e.g., bowfin, cichlids, arapaima)
268
Teleost Adaptations in reproduction: Viviparity
- Evolved independently in at least 12 lineages
- But only 3% of teleosts viviparous
- e.g., guppies, mollies, swordtails (“live bearers”)
- Matrotrophic: Additional nutrition comes from the female on top of the yolk of the egg
- With internal fertilization
- e.g., seahorses? Female lays eggs but males “give birth” or just carry or brood the eggs in their pouch
269
Teleost Adaptations in reproduction: Unusual modes of reproduction
-e.g., Hermaphroditism: Single fish may be male and female (not both at the same time except for Rivulus)
-2 types:
a. Simultaneous (rare)
§ e.g., Rivulus capable of self-fertilization
b. Sequential
§ e.g., clownfish (“protandrous”=male first)
-Colonies with breeding pair (large male and large female) and non-mating small males
-If dominant female dies, large non-mating male changes sex
-§ e.g., wrasses (“protogynous”=female first)
-Small females change into a male if there is a need
270
Protandrous vs Protogynous
- Types of sequential hermaphroditism
1) Protandrous: e.g., clownfish (“protandrous”=male first)
- Colonies with breeding pair (large male and large female) and non-mating small males
- If dominant female dies, large non-mating male changes sex
2) Protogynous:
- § e.g., wrasses (“protogynous”=female first)
- Small females change into a male if there is a need
271
Teleost Adaptations in extreme habitats: Deep sea fishes
- At least 75% oceans >1000 m deep and completely dark (aphotic)
- Photosynthesis limited to approx. top 100 m=limited in nutrition
- Food limited and decreases with depth
- High pressure (20-1000 atmospheres)
- Cold temperatures (3-10°C)
- Low oxygen
- Inhospitable environment but large and stable (no change seasonally)
- Approx. 10% known fish species from deep sea (an underestimate because we don’t know what’s actually down there)
272
Teleost Adaptations in extreme habitats: Bathypelagic fishes
-e.g., gulper eels, anglerfishes, hatchet fishes (Fig. 6-19), Viper fishes
-Inactive, with energy-saving features:
○ Less dense bone and less skeletal muscle
○ No scales
○ Small eyes and poorly developed Central Nervous System (except parts associated with lateral line and olfaction)
○ Small gills, small hearts
○ Reduced or absent swim bladders
• Large jaws, teeth, distensible guts but small body size
• And abundance low, especially at high latitudes
• Almost all black, but many with photophores (bioluminescence)
○ Species and sex-specific for attracting males
• Other reproductive strategies to find mates at low abundance:
○ Parasitic male anglerfish (Fig. 6-19d)
○ Can have two males attached or just one
○ Mate for life to not lose them in the dark
273
Th anglerfish has what adaptations in terms of mating in their deep-sea environment?
-its a bathypelagic fish
-reproductive strategies to find mates at low abundance:
○ Parasitic very small male anglerfish
○ Can have two males attached or just one to the very large female
○ Mate for life to not lose them in the dark
-
274
Teleost Adaptations in extreme habitats: Cave habitats
-Most also completely dark, with limited nutrients
-Fish characterized by energy-saving adaptations
-Cave-dwelling fish evolved independently in at least 11 families
-Incl. 6 ostariophysan families (e.g., catfishes, tetras)
-But similar adaptations:
○ Eyes reduced or absent
○ No pigmentation
○ Pelvic fins reduced or absent
○ Small body size (< 15 cm)
-Many gill brooders
-With reduced ability to regulate metabolic rate
275
Teleost Adaptations in extreme habitats: Polar habitats
-Very cold temperatures (1 to -1.9°C) but uniform
-And long summer days make primary production seasonally high
-Particularly in Antarctic
-Adaptations to extreme cold include:
○ Glycoproteins in blood lower freezing point (e.g., Antarctic “cods”)
○ Also, since blood viscosity increases at low temperatures, some (e.g., icefishes) lack red blood cells (RBCs) and hemoglobin
-Dissolved oxygen high at low temperatures
-And low metabolic requirements
