Lecture 4: Invertebrates II and Vertebrates Flashcards
1
Q
Protostomes
A
- Tripoblasts
- Blastopore becomes mouth first
- Bilateral symmetry
2 Major derived traits:
- Anterior Brain
- Ventral nervous system consisting of longitudinal nerve cords
2 Major clades:
- lophotrochozoans
- ecdysozoans
2
Q
Lophotrochozoans
What animals?
A
- Protostomes
- Flatworms. annelids, mollusks
3
Q
Defining Features of Lophotrochosomes
A
(not universal)
*likely traits both in a common ancestor, then lost over time
- Lophophore
- circular or u-shaped ring of tentales around the mouth
- food collection and gas exchange - Trochophores
- Free-living larva
- Move by beating a band of cilia
- cilia also bring plankton closer to the larva so it can be captured and ingested
4
Q
Flatworms
A
(platyhelminthes)
- Acoelomate
- lack a gas transport system (flat so cells near surface obtain oxygen, no heart or circulatory system)
- move using cilia
- blind gut (only one opening)
- most are parasites (can absorb digested food from host, do not require elaborate feeding or digestive organs)
- sephalization (head with basic chemoreceptors, two simple eyes, tiny brain with longitudinal nerve cords)
- include tapeworms and flukes
5
Q
Flukes
A
(flatworm)
Schistosomiasis – snail host
- deposit eggs in open water
- fluke burrows into skin and matures
- migrates to preferred tissues
6
Q
Tapeworms
A
(flatworm)
- flea host
- flea is eaten or fecal contamination (meat, water)
- eggs in feces
7
Q
Annelids
main distinction
A
(ring worms)
- segmented bodies
- body divided into repeated segments
- ability to move different parts of its body independently of one another
- segments develop from growth zone, oldest in front, youngest in back
ex: bristleworms, earthworms, leeches
8
Q
Annelids
body systems
A
- complete gut
- coelomates
- move using muscle contraction
- NERVOUS SYSTEM
- small brain
- ventral nerve cord
- seperate nerve center (ganglion) controls each segment connected and coordinated by ventral nerve cords
- CIRCULATORY SYSTEM
- blood circulates within vessels
- ring vessels near anterior have muscles that act as hearts
- GAS EXCHANGE
- thin permeable body wall serves as a surface for gas exchange
- no gills or lungs
- restricted to moist environments
9
Q
“Many hairs” Annelids
A
- bristleworms
- PARAPODIA - thin outgrowths from body wall
- for gasexchange, movements
- covered with stiff bristles for gripping
*paraphyletic - not all in same clade
10
Q
“pack-saddle” Annelids
A
- NO parapodia
- hermaphrodites
- thick ring shaped “pack-saddle” around one section of their skin
- holds coccoon in which eggs and sperm are deposited and stored until they hatch
Earthworms - digest soil
leeches - feed on blood, used in medicine tp reduce fluid pressure and prevent blood clotting
11
Q
Mollusks
main features
A
- not considered to be truly segmented
- three major body components
- FOOT - muscular structure for support and movement
- VISCERAL MASS - centralized housing for the organs
- MANTLE - tissue covering the visceral mass that can secrete a hard shcll in many species
12
Q
Mollusks
body systems
A
-complete gut
- REDUCED coelom (small space around heart)
- instead have a large, fluid filled cavity - HEMOCOEL (cavity for hemolymps - blood and interstitial fluid)
- NERVOUS SYSTEM
- simple brain - nerve ring of connected ganglia
- two pairs of ventral nerve cords
GAS EXCHANGE
- gills
CIRCULATORY SYSTEM
- open system
- heart pumps blood
- blood and other fluids empty into hemocoel
- fluids move around hemocoel and deliver oxygen to internal organs
13
Q
Types of Mollusks
A
Chitons
- 8 overlapping dorsal plates
Bivalves
- clams, oysters, scallops, mussels
Gastropods
- snails, slugs, sea slugs
Cephalopods
- squids, octopuses, nautiluses
- enhanced mobility
- modified mantle allos water to be forcibly ejected from the cavity - propulsion
- most complex invertebrate nervous system
- branched foot, tentacles
14
Q
Ecdysozoans
main types
A
(protostomes)
- nematodes and arthropods
15
Q
Ecdysozoans
main features
A
- defined by having external covering or CUTICLE
- secreted by underlying epidermis
- provides animal with protection and support
- once formed it cannot grow
- must molt and replace cuticle
- can be thin (worm like)
- allows exchange of gases, minerals, water
- restricted animal to moist habitats
- can be thick (arthropods)
- exoskeleton
- impedes movement and passage of oxygen/nutrients
- jointed appendages evolve
- can invade dry land because do not dehydrate
16
Q
Namatodes (roundworms)
body systems
A
- Ecdysozoans
- pseudocoelomates
- thick outer cuticle that is shed throughout life
- unsegmented
- complete gut
- GAS EXCHANGE
- through both cuticle and gut
- no gills or lungs
- NO circulatory system
- NERVOUS SYSTEM
- brain = nerve ring
- four peripheral nerves run length of body
17
Q
How do nematodes eat?
A
Scavengers:
- soil, bottom of lake or sea
Parasitic:
- multiple stages of life ycle
- heartworms
- hookworms
- pinworms
- whipworms
- trichinella worms
18
Q
Arthropods
main features
A
Ecdysozoans
- jointed appendages - complex movement
- most species rich group of animals
- 10^18 alive at any time
- segmented bodes (2 or 3)
- head, (thorax), abdomen
- muscles attached to inside of rigid exoskeleton
19
Q
Arthropods
body systems
A
- complete gut
- reduced coelom but have large hemocoel cavity
- open circulatory system
- heart pumps blood through hemocoel cavity
- fluid filled cavity bathes organs in oxygen and nutrients
- no distinction between blood and interstitial fluid: hemolymph
- various systems of gas exchange
- nervous system
- simple brain
- ladder like paired ventral nerve cords with ganglia at each segment
20
Q
4 Major Arthropod Groups
A
- Myriapods
- chelicerates
- Crustaceans
- Hexapods
21
Q
Myriapods
A
- Millipedes and centipedes
- One (centipedes) or two (millipedes) pairs of legs per segment
- Gas exchange via trachea (no lungs)
*centipedes and millipedes do not have 100 and 1,000 legs
22
Q
Chelicerates
A
- Horseshoe crabs
- Arachnids
- Spiders, Scorpions, Mites, Ticks
- Most have 4 pairs of legs
- Many have gas exchange in folded sacs of alternating air & hemolymph
23
Q
Crustaceans
A
- Shrimp, Crabs, Crayfish, Barnacles
- Dominant marine arthropod
- Gills which can be located on body or as modified appendages
24
Q
Hexapods
A
- Insects
- 1 million species of insects are known.
- Up to 50 million species may exist!
- Dominant terrestrial arthropod
- Six legs on thorax
- Many have two pairs of wings
- Evolutionary advantage
- Unique mechanism of gas exchange
- Sacs & tubular channels that extend from external openings inward to tissues throughout the body
- Complete metamorphosis – changes between molts are dramatic
- Incomplete metamorphosis – changes between molts are gradual
25
Body cavity in protostomes
- cannot group whole protostomes clade by body cavity type
- likely the common ancestor was coelomate
- loss or partial loss of body cavity seems to have arisen independently several times
26
Deuterostomes
| main features
- blastopore develops into anus
- triploblasts
- coelomates
- no external skeletal suport structures
- some have segmented bodies (vertebrates)
- common ancestors had bilateral symmetry and pharyngeal slits (gills)
- lost by echinoderms
- complex behaviors
27
3 Phyla of Deuterostomes
1. Echinoderms
- sea stars and sea urchins
2. Hemichordates
- acorn worms and pterobranchs
- worm like marine species
3. Chordates
- sea squirts
- lancelets
- vertebrates (humans!)
28
Echinoderms
| body systems
- bilateral - as larva
- pentaradial - as adults
- no head
- move slowly and equally well in all directions
- oral/mouth faces sea floor
- aboral side (anus) faces top
- complete gut
- open CIRCULATORY system with no heart
- radial nerve net with no brain
29
Unique Strucural Features of Echinoderms
- system of calcified internal plates covered by thin layer of skin and muscles
- fuse to form internal skeleton
- water vascular system
- water filled canals lead to tube feet
- tube feet are suction cups
- do gas exchange, locomotion, feeding
30
3 Main Groups of Echinoderms
- sea lillies and feather stars
- sea urchins and sea cucumbers
- starfish (seastars) and brittle stars
31
Chordates
| 3 derived traits
1. dorsal hollow nerve chord
- devs into brain and spinal cord
2. Tail that extend beyond anus
- in many species only present in early dev but lost in adults
3. Dorsal supporting rod called notochord
- in most vertebrates a vertebral column develops and only remnants of the embryonic notochord remain
32
Non-derived traits of chordates
1. pharyngeal slits (present in dev but lost in many adults)
2. complete gut
* came earlier than common ancestor of chordates
33
3 Chordate Clades
1. Lancelets
- ~ 30 species
- cephalochordates
- very small
- derived traits present as adults
```
2. tunicates
~ 3000 species
- urochordates
- bag like body enclosed in tough tunic
- swimming larva with tail, dorsal hollow nerve chord, pharyngeal slits, notochord
- adult is sessile and lacks all three
```
3. vertebrates
- ~62,000 species
34
Vertebrates - Defining Feature
- segmented
- vertebral column = defining derived trait
- dorsal support structure that replaces notochord during early development
- evolved from marine ancestors
- series of derived traits define different clades
35
Key features of Vertebrates
- anterior skull with large brain
- rigid internal skeleton supported by vertebral column
- internal organs suspended in coelom
- well developed circulatory system driven by contractions of a ventral heart
--> allow dev of large active animals
36
Main Vertebrates:
- lampreys
- chondrichthyes
- Ray-finned fishes
- lobe fins - Coelacanths
- lungfishes
- amphibians
- amniotes... include:
- reptiles
- mammals
37
Lampreys
- most basal group of the vertebrates
- complete skull
- distinct and separate vertebrae
- Cartilage - not bony
- filter feeding larvae resemble lancelets
- most are parasitic
- round mouth that attaches to prey and bores through the flesh (no jaw)
38
Chondrichthyes
Main idea: Jaws, teeth and paired fins
- Cartilaginous fishes
- no bones
- sharks, rays, skates
- evolution of jaws via modifications of skeletal archs supporting the gills- gnathostomes
- teeth makes jaws more effective
- paired fins stabilize position of fish in water
39
Ray Finned fishes
Main idea: bony skeleton and swim bladder
- eels, sea bass, grouper, salmon
- fins are bony spines covered by a wed of skin
SWIM BLADDERS
- sacks to store air in to supplement
- useful if oxygen in short supply
- buoyancy
- fish can adjust amount of gas in swim bladder to control depth at which it stays in water without expending much energy
BONY SKELETON
- internal skeleton of calcified, rigid bone
40
What needed to happen to transition from marine to land life?
1. Lungs
- can obtain and store oxygen out of the water
- swim bladder is organ to store oxygen
- leads to dev of lung
2. Legs
- must change structure of fins to support on land
- bony skeleton gives a way to suport ourselves but not the right shape
- lung(s) only would not be enough to survive on land
41
Lobe fins: Coelacanths
Main features:
- 2 pairs muscular jointed fin
- stronger bones
- rod-shaped bones
*Key: better at moving on land
42
Lungfishes
Key features:
1. muscular, joined fins
- drag along in muddy areas
- live in shallow waters
- drag from shallow water to deeper pools
2. lungs
- can be out of water in mud, burrow and survive
43
How did organisms begin to colonize land?
Organisms had:
1. lungs
2. lobed fins/legs
- coopted structure to move on land
- used features for brief foraging trips on land
ex; Tiktaalik: ancient vertebrate that possessed appendages intermediate between fins and limbs
44
Amphibians
- Animals: frogs, toads, salamanders
- Tetrapods - legs to move on land
- aquatic and terrestrial adaptations
- need water to reproduce - eggs not protected
- undergo metamorphosis from aquatic larvae to terrestrial land animals
- often confined to moist environments - lose water through skin
- many lay large number of eggs which they abandon once fertilized
* need water because don't have features that allow them to survive out of water completely - egg, skin, etc
45
Amniotes
Main derived character: Amniote egg
- Water conserving traits - allow them to colonize a wide range of terrestrial habitats
- egg - membrane prevents evaporation of fluids, store large amounts of food so embryo can be further developed when hatched
"water"
- impermeable skin covered with scales, hair or feathers
- kidneys to concentrate urine
- rib cage to ventilate lungs
46
Reptiles
- animals - snakes, lizzards, turtles, crocodiles, alligators, birds
- birds are only living member of extinct dinosaurs
Key features:
- scaled waterproof skin
- usually lay shelled eggs on land
- ectotherms (cold blooded), except birds
47
Evolution of flight
Origin: Group of dinosaurs with hollow bones
- made them lighter and more mobile
- bipedal stance and elongate forelimbs
- scales were modified to form feathers
- strong lightweight surface
"egg came before the chicken"
48
Mammals
Key features:
- sweat glands (sweat to cool)
- mammary glands (milk to nourish)
- hair (protective and insulating)
- four chambered heart (separates oxygenated blood from deoxygenated)
- internal fertilization (embryo undergoes dev in mothers uterus)
- high metabolic rate (endotherms)
- larger brain (social structure, communication, nourish young)
49
Three major groups of mammals
1. protherians
- egg laying
- duck billed platypus, spiny anteater
2. marsupials
- pouched mammals
- short gestation, young are born immature
- climb into pouch
kangaroos, opossums
3. eutherians
- placental mammals
- highly developed at birth
- some evolved aviation ability or returned to water
- bats, dolphins, seals, rodents, wolves, elphants, humans
- about half of eutherians are rodents
50
Primates
Origin: insect eating mammals in cretaceous period
2 major clades
1. prosimians
- lemurs and lorises
2. anthropoids
- tarsiers, monkeys, apes
51
Defining features of primates
* influenced by demands of living in TREES
- hands/feet for grasping
- opposable digits
- large brain and short jaws
- excellent hand-eye coordination
- complex social behavior
- extensive parental care
52
Arthropods: monkeys and apes
| 3 kinds
1. old world
- first to evolve were in africa/asia
- no prehensile tail
- trees or terrestrial
2. new world
- diverged from old world monkeys
- now only in south and central america
- long prehensile tails
- all live in TREES
3. apes
- branched off from old world monkeys 35 million years ago
- lesser apes: gibbons
- great apes: orangutans, gorillas, chimps, humans
53
humans and Chinmpanzees
- Share a common ancestor
- ancestor split to:
1. chimpanzees
2. Australopithecus
*human evolution is not a linear progression
54
Distinguishing features of humans
- upright posture and bipedal
- larger brain capable of complex and symbolic thought
- manufacture and use of complex tools
- reduced jawbones and jaw muscles
- shorter digestive tract
55
Hominid Clade
- Australopithecus = ancestor
- gave rise to many species of hominins:
- coexisted peacefully
- group of larger ones became extinct
- group of smaller ones survived --> gave rise to genus homo
56
Homo Habilis
- 2.5 mya
- oldest evidence of tool use
- relatively large brain
- intermediate between australopithecus and humans
- walked upright
- made/used stone tools to enhance hunting
57
Homo Ergaster Trade off
Jaw vs Brain
- brain increases in size while jaw decreases
- developmentally linked
- childbirth restraints
- juveniles of both humans and chimps have similar skulls
- advancements such as cooking food allow smaller jaws
- evolutionarily favored by increasingly compelx social life
58
2 species from Homo Ergaster
1. Homo neanderthalensis
| 2. homo sapiens
59
Out of Africa Hypothesis
- oldest known fossils of homo sapiens in ethiopia
- DNA studies (mitochondria) suggest all living humans can trace ancestry back to single African homo sapiens woman who lived 160,000-200,000 years ago
- small population lived solely in Africa for a long time, conditions were rough
- fossil evidence suggests that our sepcies emerged from africa in 1 or mroe waves when climate improved
- three broad groups
- oldest fossils outside africa are only 50,000 years old
60
Tetrapods
4 legged terrestrial vertebrates
- amphibians
- amniotes
61
In what era did the colonization of land occur?
Paleozoic
62
2 Major Amniote Clades
Reptiles
| Mammals
63
Homom Genus
1. homo habilis
2. homo erectus
3. homo ergaster
64
Homo Erectus
- first to leave africa - dispersal
- taller than H. Habilis
- smaller brain than modern human with thick skulls
- used fire
- hunted large animals
- stone tools
- extinct
65
Homo Ergaster
- much larger brain
- much smaller jaw
- more complex social life
- rituals and concepts of life and death
- gave rise to neanderthals and homo sapiens
66
Neanderthals
- outside of Africa in Europe and Asia - cooler climates
- short, stocky and powerful
- brain slightly larger than ours
- disappeared around 28,000 years ago
- likely exterminated by homo sapiens
67
Homo Sapiens
- modern humans
- migrated out of africa 60-70,000 years ago
- used sophisticated tools
- evolved larger and more sophisticated brains
- complex culture and language
