Chrodata Flashcards
(43 cards)
1
Q
Chordate Characteristics
A
- Notochord
- Dorsal tubular nerve cord
- pharyngeal slits/pouches
- Endostyle/thyroid gland
- Muscular tail
2
Q
notochord
A
- fluid-filled cells that form a dorsal stiff, but somewhat flexible rod
- precursor to vertebrate backbone
- notochord appears in all vertebrate embryos (disappears during development)
3
Q
dorsal tubular nerve cord
A
- initially hollow, but cavity often obliterated with growth
- protected by the vertebral column in vertebrates
- lies above notochord during development
4
Q
pharyngeal slits/pouches
A
- evagination of the pharynx–> gill slits in fish, pouches–> other structures like parts of the ear in terrestrial vertebrates
- 3 little bones in ear developed from this
5
Q
endostyle/thyroid gland
A
- on the pharyngeal floor
- secretes mucus to trap food or as a gland, secrete hormones
6
Q
muscular postanal tail
A
for propulsion
7
Q
Subphylum Urochordata (tunicates)
A
- all marine
- most adults are sessile, larvae are planktonic
- solitary or colonial as adults
- adults function analogously to sponges–> water entering top, depositing food on a mucus-bearing endostyle on the pharynx, and exiting an excurrent siphon
- have a heart and circulatory system, and a single ganglion
- like many sedentary animals, tunicates are hermaphroditic (both sexes in one organism)
- adults don’t look much like chordate, but larvae reveal relationship
8
Q
Class Ascideacea
A
sea squirt
- most common tunicates
9
Q
Class Thaliacea
A
- salps
- not tunicates
- urochordates
10
Q
Subphylum Cephalochordata
A
- Lancelets (“Amphioxus”)
- marine, 32 species
- a clasic “protochordate”
- feeding like in tunicates: water taken in the mouth, passed over the sticky pharyngeal endostyle, and then expelled through the pharyngeal slits
- pharyngeal slits are not gills–> organism is small enough that it gets oxygen by diffusion through body wall
- locomote by flicking posterior portion like fish
- fully closed circulatory system: heart–> paired aortas–> capillaries–> veins–> heart
- dioecious (2 separate sexes) with external fertilization
11
Q
Vertebrate morphological/physiological adaptations
A
- development of an endoskeleton
- Pharyngeal slits become gills
- Ventral heart pumps blood anteriorly into ventral aorta which divides into aortic arches–> surround pharyngeal slits of both sides to effect exchange of respiratory gases; arches fuse dorsally into dorsal aorta
- Blood has hemoglobin
- Gut becomes muscularized
- brain becomes 3 parted
- Sensory appendages
12
Q
benefit of endoskeleton
A
- allows large size
- segmental vertebrae enclose nerve cord (replace notochord during embryonic life) and have neural spines for segmental muscle attachment
13
Q
benefit of pharyngeal slits becoming gills
A
- functional change from food gathering to respiration
14
Q
benefit of hemoglobin
A
carries respiratory gases from or to gills or lungs
15
Q
benefit of muscularized gut
A
processes large food material
16
Q
3 part brain benefit
A
- fore, mid, hindbrains
- sponsors active, predatory lifestyles
17
Q
benefit of sensory appendages
A
- visual, auditory, olfactory
- develop from interaction of neural and epidermal tissues
18
Q
Earliest vertebrates
A
Agnatha (“lacking jaws”)
19
Q
earliest agnathans
A
- Ostracoderms
- persisted for most of Cambrian period, before jawed fishes appeared
- hoovered up organisms/organic material from substrate, though some predatory
- small, had sophisticated dorsal nervous system and sense organs
20
Q
Cyclostomata
A
- remnant agnatha
- Myxini (Hagfishes)
- marine
- secondary loss of many vertebrate characteristics (no vertebrae in adults, rudimentary in embryos)
- hexaploidation of genome in evolution—> lost many genes during embryonic life, somatic cells lose many genes
- blind, but good olfactory sense
- major production of slime
- saprophagous: feed on dead/dying fish, marine mammals (esp whales)
- attach with keratinized teeth on tongue, form a knot
21
Q
Petromyzontida
A
- lampreys
- 7 gill slits
- eyes
- adults are major parasites of fish–> attach and suck like leeches
- sea lampreys have decimated fisheries in Great Lakes (esp trout)
- Niagra Falls= no upstream migration until Welland Canal deepened in 1910
- Anadromous life cycle: eggs in streams, larvae burrow in substrate, adults move to ocean but can remain in lakes
- effective control by fishing (reduction of food) and specific larvicides applied to streams
22
Q
How do lampreys attach to fish
A
- attach with keratinized teeth and suction
- tongue protrudes for ripping flesh
23
Q
Gnathostomes
A
- anterior pharyngeal arch becomes mandibular archa dn extends to form jaws–> predation possible
- pectoral and pelvic girdles form from vertebral column–> accompanying pectoral and pelvic appendages
24
Q
Chondrichthyes
A
cartilaginous fishes
- two subclasses: Elasmobranchii, chimaeras
25
Elasmobranchii
- sharks, rays, and skates
- whale shark
- hammerhead shark (good binocular vision, good distance perception)
- skate and ray (have gill slits, mostly benign, stingrays have stinging spines)
- manta ray (filter feeders, harmless, flap their fins like a bird to swim)
26
Sharks
- teeth are continuously produced and shed
- buoyant (saves energy) due to high lipid content
- streamlined shape optimal for minimum drag
- asymmetrical tail tends to force shark downward--> counteracted by angling pectoral fins
- dorsal fins help prevent yawning (help straight-line movement); for stabilization
- males have claspers--> internal fertilization
- females oviviparous= retain eggs--> live young
- many sharks have low fecundity(number of offspring) and are very long-lived--> very vulnerable to exploitation (however, young are more likely to survive with more parental care)
- shark-fin soup delicacy in Asia--> heavy exploitation and release of finless animals
- lateral line runs all along the body--> tube that has openings to surface, adjacent to tubes are nerve cells that sense the pressure of liquid--> senses changes in pressure around them--> can sense something in the water and find prey
- two anterior pharyngeal arches have become the jaw--> only 5 gill arches
27
shark novel sensory organs
- lateral line runs along whole side of the body; sensitive to pressure; also in ray-finned fishes
- Ampullae of Lorenzini= sense bioelectric fields of potential prey organisms (only in sharks and rays)
28
electric ray
- torpedo
- most animals generate mild electric fields due to nerve and muscle activity
- electric rays and electric eels put a battery og muscle fibers together that generate asymmetric action potentials resulting in powerful electric shocks
- make it so one side is more positive, other is more negative--> generates high currents by stacking muscles next to each other
29
Holocephali
- chimeras, ratfish
- no teeth, flat plates instead
- apparently eat anything they can crunch
- abundant fossils in Cretaceous, but much less so now
30
Osteichthyes
- "bony fishes"
- bone replaces cartilage during development
- operculum= flap covering gills
- swim bladder= gas filled, for buoyancy in may or respiration in some. Originates as a gut diverticulum--> becomes the lungs of tetrapods
- two subclasses: Actinopterygii and Sarcopterygii
31
Actinopterygii
- ray-finned fishes
- swim bladder is on dorsal side of gut
- heart pumps blood forward into aortic arches
- gills come after blood goes into heart--> heart of fish has deoxygenated blood
- main propulsion from caudal fin; other fins direct the body, pelvic fin changes angles
- brain closely connected with eyes
- 3 groups: Bichir, sturgeon (caviar), paddlefish
32
teleost
- actinopterygii
- 96% of all living fish species
- symmetrical tails
- lighter, less armored scales
- reef fish, mud skipper, luminescent fish of deep oceans
33
Sarcopterygii
- lobe-finned fishes
- Coelacanth, Lungfishes
34
lungfishes
-lungs allow ability to live out of water for long periods
- Australian and African species burrow in mud and form cocoon during dry seasons
35
Coelacanth
- fins have bony extensions
- thought to be extinct, found in Madagascar/Phillipines
36
locomotion (fish)
- myomeres ("muscle section") generate force, bending the body
- each myomere extends in a "w" to spread out the force
37
slow moving vs fast moving fish
- slow moving= wiggle whole body; better for maneuverability
- fast= only move caudal fin--> less drag
38
Swim bladder
- gas filled--> buoyancy
- volume must be constant, but as pressure increases with depth in water, the bladders need more gas
- gas gland will secrete more gas, provided by blood in rete mirabile
- if a fish then ascends, gas is dumped via the ovale, opened by constrictor muscles
- gases are usually O2 and CO2
- lipids also help in buoyancy
39
gill function
- water enters mouth either by fish moving through water or by flapping the operculum
- as it is ejected through gill slits, it passes over gill filaments, giving up O2 to blood capillaries, and picking up CO2
- O2 gain and CO2 release by fish occurs because metabolism--> less O2 and more CO2 is entering blood
- exchange occurs by diffusion but is enhanced by countercurrent blood flow
40
osmotic regulation
- most vertebrates in salt water are hypoosmotic
- a fish in salt water will lose water or gain salts or both--> secretes salts through gills and concentrates urine
- a fish in fresh water will gain water and lose salts or both--> fish in freshwater absorbs salts actively in gills and pee copious, dilute urine
41
Salmon
- eggs are laid in small running freshwater streams
- young grow for a few years there and then migrate downstream to oceans
- grow to adulthood over several years in oceans and then return to their natal stream to mate and lay eggs
- find their natal streams with considerab;e fidelity after wandering widely in oceans--> memory of scent
- "anadromous life cycle"
42
major survival problems of salmon
- fishing
- dams limiting migration
= deforestation of upstream banks--> loss of shade--> water too hot
- siltation from development/poor farming
- competition from introduced sport fish species
43
eels
- breed in Atlantic ocean
- "catadromous" life cycle= opposite of salmon
