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

chordata: petromyzontida

lampreys; aquatic ectoparasites; sister taxa to mynixi; vertebral column with flexible cartilage sheath (no collagen) with small projections; no jaws, keratin teeth; evolved paired fins, inner ear with semicuricualr canals for balance

codont

extinct early vertebrae with mineralized teeth, suspension feeder

mineralization of endoskeleton began in…

mouth

jaws evolved from…

anterior gill arches (hypothesized)

lateral line system

organs in rows on body sides sensitive to vibrations; do not need to see, can feel instead

chordata: chondrocytes

sharks, skates, rays; mostly cartilaginous skeleton; placoid tooth like scales

sharks

chondrocyte; powerful swimmers, liver oil for buoyancy, sink if stop swimming, can pump water over gills if resting; receptors in head detect electric field, acute olfactory senses; predators (swallow prey whole, take large chunks with rows of teeth)

skates and rays

chondrocyte; dorsoventrally flat, use enlarged pectoral fins to fly underwater; crush prey with jaws, spikes and poisonous barbs on tails for defense

chordata: osteichthytes

bony fish; ray finned fishes (Actinopterygii); lobe finned fishes (Actinistia); lungfishes (Dipnoi); ossified skeleton; operculum; internal or external fertilization, varied parental care

ray finned fishes (Actinopterygii)

(Actinopterygii); bony rays support fins; seahorses, eels, salmon

lobe finned fishes

(Actinistia); rod-shaped bones in fins; coelocanth

lungfishes

(Dipnoi); have lungs, can breathe air

ossified skeletion

skin with bony scales, mucus to reduce drag; mineralized skeleton throughout whole body

operculum

protective bony flap; covers gills

lineages that evolved lungs

bony fish living in oxygen poor shallow estuaries

lungs evolved into the…

swim bladder

swim bladder

air filled sac to control buoyancy

lung-bearing lineages evolved…

lobe fins to ‘walk’ along bottom

tertrapods

animals with 4 limbs and digits

modifications from land…

head separated form body by neck; bones of pelvic girdle fused to backbone (lets them stand against gravity

tiktaalik

oldest known official tetrapod fossil, insight into how ancestor looked

chordata: amphibia

frogs, toads, salamanders, caecilians; carnivores that feed with sticky tongue to catch prey; rely on skin for gas exchange; throat muscles to inflate lungs; some aquatic some terrestrial; camouflage or aposematic coloration; external fertilization, eggs must be wet

toads

leathery skin, live in dry habitats

caecilians

lost legs, nearly blind burrowers

frogs

court females with loud vocalizations

salamanders

long tail