Animal Evolution

cnidaria

diploblastic with mostly acellular mesoglea; radial symmetry, nerve net, incomplete gut

medusae cnidaria

planktonic, predatory

polyp cnidaria

sessile, asexual

mesoglea

noncellular, gelatinous, structure and buoyancy

cnidocytes

stinging cells used to capture prey by cnidaria; may have toxins and chemicals; shared derived character

planula

free swimming larvae of cnidaria that sexually reproduce

anthozoa

sea anemones, corals

corals

colonies of polyps, calcium carbonate skeleton built by successive generations of anthozoa, basis of diverse communities

zooxanthelle makes anthozoa

autotrophic; symbiotic relationship

medusozoa

dominant stage; painful and toxic poison injections; moon jelly, box jellies, sea nettle; sea turtle resistant

colonies of polyps

Portuguese man-o-war, by the wind sailor

annelidia

homoplasious true segmentation; true worms in sea, freshwater, soil; coelomates, complete gut, chaetae; hermaphrodites (sexual)

chaetae

chitinous bristles

trochophore larva

shared with mollusks

annelida lifetyles

predators, filter feeders, detrivores, parasites, worms; some have parapodia

parapodia

pairs of paddle like appendages used for locomotion, gills

mollusca

marine, freshwater, terrestrial; filter feeders, herbivores, carnivores; coelomates, complete gut, reproduce sexually; gills, need moisture to move/gas exchange

foot (mollusca)

large muscle used for movement

radula (mollusca)

rasping feeding structure made of chitin teeth that scrape surfaces, drill, or harpoon food

mantle

protects internal organs, secretes shell

polyplacophora (mollusca)

chitons; basal taxon; grazing herbivores; distinctive 8 overlapping shell plates

gastropoda (mollusca)

coiled external shell; snails, slugs, nudibranchs; grazing herbivores and predators

gastropoda (mollusca)-nudibranches

eat cnidarians and keep cnidoctyes on back for protection; use mucus to prevent triggering stinging cells

flatworms mimic…

nudibranch toxicity (bastian)

bivalvia- mollusca

clams, oyster, muscle, scallops, filter feeders; two shells, simple eyes, adductor muscles to close shells, no radula (enlarged gills)

adductor muscles

holds bivalvia shells closed

cephalopoda

squid, cuttlefish, octopus, nautilus (basal taxon, external shell only); predators; modified foot and radula, complex eyes, beak

cephalopoda radula

beak like jaws, poisonous saliva

cephalopoda foot

tentacles, siphon (used for jet propulsion)

cephalopoda traits

shell moved inside mantle, gradually lost; chromataphores

chromatophores

specialized cells in skin containing pigments under precise nervous and muscular control; used for camouflage, communication

arthropoda

most diverse animal group; coelomates, sexual reproductions, separate sexes; exoskeleton of chitin; true segmentation; jointed appendages; well developed sensory system

arthropoda cuticle

exoskeleton made of chitin; can be flexible or hard, molt leaves body vulnerable until it hardens; keeps moisture in

true segmentation

jointed appendages lead to specialization of function

tagmosis

fusion of segments into functional units, division of labor between body parts (usually thorax, head, abdomen)

arthropoda: chelicerata

aquatic, terrestrial, predators, parasites; (ex: horseshoe crabs, arachnids); have chelicerae; two body regions cephalothorax and abdomen

cephalothorax

head and thorax together

book lungs

respiratory organs composed of many fine leaves; situated in the abdomen and have openings on the underside

arachnids

chelicerata; 4 pairs of legs, chelicerae, pair of pedipalps; unique web spinning, spinnerets

chelicerae

appendages that serve as pincers or fangs (plus poison glands in spiders)

pedipalps

appendages modified as sensory organs or for feeding (sucking mouthparts in ticks)

spinnertes

used to wrap nuptial gifts to females

arthropodia: crustacea

mainly aquatic; shellfish, pill bugs, barnacles; plankton larvae, filter feeders, scavengers; multiple modified appendages for feeding, respiration (most have gills)

chordata

4 derived characteristics (notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail)

notochord

longitudinal, flexible rod located under nerve cord; (vertebral disk all left in humans), fluid filled cells incased in fibrous tissue

dorsal, hollow nerve cord

develops from ectoderm rolled into tube; brain, spinal cord

pharyngeal slits

series of pouches separated by grooves along sides of pharynx (behind mouth); allows water to enter, exit body without passing through digestive tract; filter feeding and respiration

post-anal tail

tail that extends posterior to anus; used for locomotion in aquatic chordates