Unit 4 Flashcards
What characteristics distinguish the animals?
- multicellular eukaryotes
- no cell wall
- heterotrophic
- internal digestion
- locomotion (movement)
Clues to evolutionary relationships among animal groups are found in
- fossils
- patterns of embryonic development
- morphology and physiology
- protein structure
- gene sequences
Layers of cells
Diploblastic - endo and ecto
Triploblastic- endo, ecto, mesoderm
Triploblastic animals
Protostomes
Deuterostomes
Protostomes
“Mouth first”- blastopore develops into mouth
“Mouth second”- blastopore develops into the anus; the mouth develops later
Together, protostomes and deuterostomes
Bilaterians
Bilateral symmetry is associated with (blank)
Cephalization
Coelomate
Earthworm- body cavity within mesoderm
Acoelomate
- no fluid filled body cavity
- movement by cilia
- platyhelminthes
Pseudocoelomate
- muscles are only on the outside
- body cavity not wrapped on both sides with mesoderm
- nematodes
What are the features of animal body plans?
Segmentation
Locomotion
Describe segmentation
- specialization of regions
- control movements
Locomotion
- Finding food, mates
- avoiding predators
Common ancestor of animals
- colonial, flagellated protists
- similar to choanoflagellates
First animals were what and what was the link?
Sponges, choanoflagellate
First three in timeline of first animals until the Cambrian explosion
- 850 MYA choanoflagellates into sponges
- 700 MYA Cnidaria break off
- 650 MYA bilateral symmetry, three layers
First three in timeline of first animals until the Cambrian explosion
600 MYA bilateral split into proto/deutero
550 MYA movement
535 MYA Cambrian explosion
Reason for Cambrian explosion
Co evolution between predator/prey could be reason for explosion
Cambrian explosion refers to
Adaptation radiation (explosion in diversity)
Proposed hypothesis for explosion
- movement, led to need for energy, which led to traits for predation and defense
- lack of prior fossils
- increased O2 content
- most species/individuals = protostomes
Protostomes
- anterior brain surrounding mouth
- ventral nerve cords
- ancestor had coelom
Based on DNA sequencing, protostomes divided into
- lophotrochozoans
- ecdysozoans
What are the major groups of lophoyrochozoans?
- Platyhelminthes
- rotifers
- bryozoan, ectoprocts, or “moss animals”
- brachiopods
- chitons
- Gastropods
- bivalves
- cephalopod
- annelid
- oligochaetes
- polychaetes
- hirudinea
Platyhelminthes or flatworms
- dorsoventrally flattened
- mouth opens into a “blind gut”
Rotifers
- tiny
- complete gut
- pseudocoel
- cilia
Bryozoan, ectoprocts, or “moss animals”
- filter feeders
- individuals are 1-2mm
- colonies
- sessile
Brachiopods
- two part shells
- resemble bivalve mollusks, but shell evolved independently
Brachiopod shell
Two halves dorsal and ventral
- reached peak abundance in the Paleozoic and Mesozoic
- only 450 species survive
Visceral mass includes
Heart, digestive, excretory, and reproductive organs
Mollusks have a blank circulatory system
Open
Describe mollusk open circulatory system
- blood washes over organs in hemocoel
- blood eventually re enters blood vessels and is pumped by a heart
Chitons
- 8 calcareous plates protect the organs and muscular foot
- marine, scrape rocks with a radula
- cling to rocks with foot
Gastropods
- snails and slugs (lost their shells)
- many are toxic and bright for warnings, others camoflauged
- land snails and slugs are the only mollusks that live in terrestrial habitats
Bivalves
- Clams, oysters, scallops, and mussels
- 30,000 species
- hinged, two part shells
- foot burrows into mud or sand
How do bivalves feed?
Water in the incurrent siphon, filtering food with gills, sort with labial palps, into mouth, water exits through the excurrent siphon
Cephalopods
- squids, octopus, chambered nautilus
- modified excurrent siphon, allowing “jet propulsion”
- have shell chambers, radula, mouth, siphon, gills
- eyes comparable to vertebrates
- head has arms and or tentacles used to capture and subdue prey
What is the largest invertebrate?
Colossal squid
Most cephalopods except octopuses have what for internal support?
Small internal shell
Annelids
- segmented
- most have a thin, permeable body wall that serves for gas exchange
- coelom, nerve cord
Oligochaetes
- have no parapodia, eyes or tentacles and few setae
- earthworms burrow in and ingest soil
- hermaphroditic, each individual gives and receives sperm
Polychaetes
Mostly marine, burrowing
Parapodia on each segment with setae
Hirudinea
- leeches also lack parapodia
- no obvious segments
- suckers: anchors that aid in movement
Ecdysozoans
- nematoda and horsehair worms
- tardigrada
- onychophora
- anthropoda
Two anthropod characteristics
Molt and jointed appendages
Ecdysozoans
- Cuticle
- one common ancestor
How do ecdysozoans grow?
Molt/shed cuticle, replaced with a larger one
Ecdysis
When did molting evolve?
500 Mya
Nematodes
- Roundworms
- Gas exchange through the cuticle
- abundant, microscopic
- elephantiasis
Horsehair worms
Thin, visible, up to a meter long, larvae
Tardigrades
Water bears
- 8 fleshy legs
- live in sands and water films on plants, lichens
Onychophorans
Velvet worms
- live in leaf litter in the humid tropics
- thin, flexible cuticle
- may look similar to arthropod ancestors
Features of Arthropoda
Exoskeleton (cuticle, chitin) -protects from desiccation, predators Muscles attached to exoskeleton Segmentation Jointed appendages
Chelicerates
Merostoma (horseshoe crabs) and arachnida
- mouthpart appendages (chelicerae)
- chelicerae grasp, don’t chew and some inject venom
- ticks
Horseshoe crabs
-changed very little over history
Myriapods
Centipedes: 2 legs per segment
Millipedes: 4 legs per segment
- centipedes prey on insects and other small amounts
- millipedes scavenge and eat plants
Crustaceans
- marine, freshwater, and terrestrial
- shrimps, lobster, crayfish, crabs
Barnacles are not
Mollusks
Local crustaceans
- devils lake
- 1/2 inch
- scuds or side swimmers
- freshwater shrimp are a key part of the aquatic food chain
- perch, walleye, northern pike eat
Insects (hexapods)
-head: one pair on antennae
-thorax: three pairs of legs and two sets of wings in most groups
-abdomen: no appendages
Ventral nerve cord
-not all have wings have been secondarily lost: lice, fleas, some ants, beetles
Metamorphosis
Changes between life stages
Incomplete metamorphosis
Changes are gradual (grasshopper)
Complete metamorphosis
Changes dramatic
Term for what occurs between molts
Instars
Decomposition/scavengers
Flesh eating beetles used in taxidermy
What groups have the most diverse with species?
Hexapoda and insecta
Insects began to diversify when?
450 Mya
Why were insects so successful in diversifying?
Flight
- 1st, new feeding opportunities
- land no other similar organisms
- open niche
How are deuterostomes identified?
1) embryonic patterns (mouth second)
2) DNA sequence
Deuterostomes still living
Echnioderms: sea stars, sea urchins, etc
Chordates: sea squirts, lancelets, and vertebrates
Characteristics of deuterostomes
- radial symmetry as adults (echinoderms)
- bilaterally symmetrical, pharyngeal slits present
- notocord, dorsal hollow nerve cord, post anal tail
- vertebral column
What features distinguish the echinoderms?
- pentaradial symmetry
- no head
- move equally well in many directions
Water vascular system
- madreporite
- stone canal
- ring canal
- radial canal
- ampulla
- tube feet
What organisms lack arms but have a complete gut?
Sea cucumbers
What are sea cucumbers tube feet used for?
Anchor to substrate
sea urchins characteristics
lack arms and are covered with spines
sand dollars characterisitcs
flattened relatives of sea urchins
What is an urchin barren?
place devoid of kelp
What effect would a decrease in the CA sea otter populations have on sea urchins and urchin barrens?
increase urchin populations, increase # urchin barrens
increase in urchin leads to a decrease in
kelp
three chordate clades
- lancelets (cephalochordates)
- tunicates (urochordates)
- vertebrates
tunicates
- sea squirts
- filters prey from water and adults are sessile
notochord
dorsal supporting rod
pharangeal slits
present at some developmental stage
pharyngeal slits are supported by
pharyngeal arches
in fish, pharyngeal arches=
gill arches that support gills
all chordates have these derived characteristics at some stage
- dorsal, hollow nerve cord
- tail extends beyond anus
- notochord
- pharyngeal slits
vertebrates probably evolved in the oceans during the (blank) period
Cambrian
(blank) replaces the notochord during early development
vertrebral column
arches—
jaw, parts of tongue, larynx, trachea, middle ear
other characteristics of chordates
- anterior skull enclosing a large brain
- rigid, internal skeleton (supports an extensive muscular system)
- internal organs suspended in coelom
lampreys characteristics
- many species parasitic
- 7 gill slits
- jawless
jaws evolved from (blank) late in
gill arches, ordovician
jaws
improved prey capture
teeth
chewing improves extraction of nutrients from food
most jawed fish have paired fins for
stabilization and swimming
median (blank) and (blank) fins stabilize the fish
dorsal and anal
(blank) fins help the fish move forward and make rapid turns
caudal
chondrichthyes
(sharks, rays)
- skeletons of cartilage
- sharks use lateral undulations
skates and rays flap enlarged (blank) fins
pectoral
bony fish had (blank) that supplemented the gills in gas exchange
gas filled sacs
ray-finned fish have sacs that developed into (blank)
swim bladders
swim bladders
organs of buoyancy (allow fish to maintain position at specific depths)
How did vertebrates colonize the land?
1) evolution of lunglike sacs set the stage for evolution of land animals (supplemented gills in low O2)
2) changes in the structure of fins allowed some fins to support themselves in shallow H2O and move to land
lobed limb vertebrates
coelancanths, lungfish, tetrapods
pelvic and pectoral fins developed into
more muscular fins
thought to have become extinct in 65 mya, but living ones were found in South Africa in 1938
coelocanths
aquatic lobe-limbed vertebrates use (blank) to become ancestral tetrapods
terrestrial food sources
devonian fossil found in 2006 has (blank) between fins of fish and limbs of tetrapod
intermediate appendages
limbs for land evolved to four (tetra) and became (blank)
amphibians and amniotes
amphibians
- 7000 species
- confined to moist habitats
- complex social behaviors
- decrease
why are amphibians confined to moist habitats?
lose H2O easily through skin, eggs dry out in air
salamanders
many live in moist soil and rotting logs
why are amphibians decreasing?
habitat, UV, pesticide, cytrid fungus
amniote egg
- impermeable to water
- embryo develops in a contained aqueous environ
- leather/brittle retain H2O and allow gas exchange
amniote egg store food in form of
yolk
four (blank) protect the embyro from drying and assist in gas exchange and excretion of Nitrogen
extraembryonic membranes
modification of egg for mammals
embryo inside mother, lost shell
during what period did the amniotes split into to major groups?
carboniferous
what two groups did the amniotes split into?
mammals and reptiles
reptiles
- 19000 species
- 1/2 birds
- turtles changed little since early mesozoic
largest lizard
komodo dragon of the E Indies - 3m long
Crocodilians includes
crocodiles, calmans, gharials, and alligators
crocodilians
- tropical and warm temps
- most time in water
- all carnivorous
crocodilian nest
-build nests on land or floating piles of vegetation; heat from decaying organic matter warms egg
Dinosaurs
150 mya- mesozoic
-some small had scales modified to feathers
birds
- 10,000 species
- dinosaurs
- bipedal, hollow bones, furcuia (wishbone), 3 fingered feet and hands, backwards pelvis
- endothermic
- no teeth
- plant dispersal
2 groups of birds
-flight vs no flight
evolution of feather
- diversification
- bones lightweight and strong, sternum forms keel where flight muscles attached
- control heat loss
mammals
- 5700 species
- coexist with dino
- diversify rapid after cretaceous
- teeth reflect diets
key features of mammals
- sweat glands
- mammary glands
- hair
- 4 chambered heart
- internal fertilization
- hair (fur)
whales and dolphins hair
cetaceans- layers of fat
two living groups of mammals
- prototherians
- therians
prototherians
duck billed platypus and echidna
-lay shelled eggs and have sprawling legs
therians
marsupials and eutherians
marsupials
- pouch
- herbivore, insectivore, carnivore
- no ocean/fly
- kangaroo largest
only marsupial in NA
viriginia opossum
eutherians
5300 species, 20 groups
- placenta, move develop birth, social hunting
- rodent and bat
- some move to aquatic
herbivore eutherians
- favored evolution of plant spines, tough leaves, toxic compounds, difficult to eat growth
- adaptations to teeth and digestive= coevolution
- large favored (lead to large carnivore favor)
eutherian (blank( evolved from a small, aboreal, insectivorous mammal
primates
primates have
limbs with opposable digits
about 6 MYA, lineage split to form chimps and the (blank) clade
hominin
earliest protohiminins =
bipedal
bipedal
more energetically economical
