Protostomes, Deuterostomes, and Homeostasis

Deuterostomes

Triploblastic, blastophore→anus, bilateral, coelomate, internal skeletons

Ambulacrarians

Marine, Larva ciliated and bilateral

Echinoderms

pentaradial symmetry, internal calcified plates form an endoskeleton, water vascular system→madreporite→ring canal→radial canals

Echinoderm examples

sea cucumbers, sea urchins, sand dollars, sea stars

Hemichordate examples

acorn worms and pterobranchs

Hemichordates

bilateral, pharynx opens to outside via pharyngeal slits 3-part body plan: proboscis, collar, trunk

Chordates

dorsal hollow nerve cord, tail extending beyond anus, notochord, and pharyngeal slits at some stage

Lancelets (Cephalochordates)

notochord used for burrowing and catch prey with pharyngeal basket

Tunicates (Urochordates)

larvae have pharyngeal slits, hollow nerve cord, notochord while adult is sessile, no notochord and filters prey through pharyngeal basket “tunic”

Tunicates (Urochordates) examples

sea squirts

Vertebrates

jointed dorsal vertebral column, anterior skull, rigid endoskeleton, internal organs in coelom, circulatory system

Hagfishes

no vertebrae (partial skull), skeleton of cartilage, no jaws, 3 small hearts, no stomach, produce defensive slime, change sex

Lampreys

complete cranium, cartilaginous vertebrae, complete metamorphosis to parasitic adult that attaches to fish

Hagfish debate

maybe sister group to all other vertebrates or sister group of lampreys

Chondrichthyan examples

rays, skates, sharks

Chondrichthyans

finned fishes with cartilaginous skeletons

Osteichthyans

ray-finned fishes, calcified bones, gills covered by operculum, many species form schools or shoals

Coelacanths

lobe-limbed fish, massive, thought to have become extinct 65 million years ago

Lungfish

lobe-limbed fishes that have lungs and gills and can burrow in dry ponds for many months waiting for water

What does Tetrapod mean?

4 legged vertebrate

What does Lobe-limbed fishes mean?

pectoral and pelvic fins joined to the body as single enlarged bone

Amphibians

confined to moist habitats, return to water to lay eggs, 3 types: caecilians, salamanders (caudates), and frogs/toads (aurans)

What is an amniote?

has amniote eggs: calcium or leathery outside relatively impermeable to water, extra-embryonic membranes, large amounts of yolk

Lepidosaur examples

lizards, snakes

Lepidosaurs

skin covered with horny scales, gas exchange exclusively through lungs, some have venom glands

Turtles (chelonians)

bony plates form a shell- an expansion of the ribs, some terrestrial, most aquatic

Archosaur examples

dinosaurs, birds, crocodilians

Archosaurs

4 chambered hearts

Crocodilians

all carnivorous, spend most of time in water, build nests on decaying organic matter

Birds

thought to emerge from theropods, flight important but metabolically expensive, endothermic, one-way air flow through lungs, 4 chambered heart

Mammals

4 key features: 1) sweat glands, 2) mammary glands, 3) hair, 4) 4-chambered heart and endothermic

Prototherian (monotremes) examples

duck-billed platypus, spiny echidna

Prototherian (monotremes)

supply milk to young licked through fur, lay eggs, sprawling legs

What does Therian mean?

amniote egg lost, no yolk-placenta and umbilical cord

Marsupials

gestation brief and young crawl into pouch to develop and feed on nipples

Eutherians

well-developed placenta, young developed at birth, social hunting behavior, some returned to aquatic habitats

Ecdysozoans

cuticle molted so animal can grow and may serve as exoskeleton

Priapulids

unsegmented, 3-part body plan, uses pharynx and proboscis to capture prey

Kinorhynchs

microscopic, 13 plated segments, proboscis

Loriciferans

tiny, body 6 plates

Nematodes (roundworms)

unsegmented, multilayered cuticle, pharynx moves material through the gut, scavenge, predators, or parasites

Horsehair worms

very thin, larvae endoparasitic, adult has no mouth and reduced gut, most freshwater

Tardigrades (water bears)

tiny, unjointed appendages, hydrostatic skeleton, no circulatory or gas exchange system, can go into dormant state

Onychophorans (velvet worms)

unjointed appendages, hydrostatic skeleton, thin flexible cuticle, live in leaf litter, shoot sticky slime

Arthropods

jointed appendages, rigid exoskeleton made of chitin, ecdysis= shedding of outer cuticular layer, open circulatory system, ganglia-brain inhibitor, compound eyes with ocelli

Chelicerate (examples)

sea spiders, horseshoe crabs, arachnids

Chelicerates

1 pair of chelicerae, 1 pair of pedipalps, 4 pairs of walking legs, most carnivorous

Myriapod (examples)

centipedes and millipedes

Myriapods

head followed by numerous segments: centipedes 30+ legs are carnivorous, millipedes 60+ legs are herbivorous

Crustacean (examples)

shrimp, lobster, crayfish, crabs, barnacles, pillbugs, isopods

Crustaceans

2 pairs of antennae, legs of various number, may pass through nauplius larval stage, has mandibles

Hexapods

head, thorax, abdomen, 6 legs, antennae, mouthparts, most have wings, tracheal system for gas exchange, metamorphosis-incomplete or complete

Protostomes

tripoblastic, blastophore forms mouth, bilateral symmetry, anterior brain, ventral nervous system

Arrow worms

blastophore becomes anus, but have ventral nerve cord, translucent, no circulatory system

Lophotrochozoans

have a lophophore- circular or U-shaped ridge with ciliated hollow tentacles, and trochophore-ciliated larva

Bryozoans

colonial and form by asexual reproduction. marine

Entoprocts

colonial, external walls secrete material to form a house, marine

Flatworms

digestive tract opens into blind sac, most endoparasites, cephalization

Rotifers

most freshwater, tiny, corona- ciliated organ on head, mastax- organ that grinds food, pseudocoel

Gastrotrichs

tiny, marine, flat surface, most simultaneous hermaphrodites

Ribbon Worms

proboscis worm, most marine, rhyncocoel cavity has proboscis with stylets inside- expelled explosively

Brachiopods

2 part shell