Week 4: Intro to Protostomes

coelom

internal body cavity between gut and body wall

acoelomate

no body cavity (platyhelminthes)

pseudocoelomate

partially lined body cavity (nematodes and rotifers)

coelomate

body cavity completely lined with mesoderm (bryozoans, brachiopods, humans)

Clade Platyhelminthes characteristics

flatworms, acoelomate, hydrostatic skeleton, bilateral symmetry, incomplete digestive tract, monoecious

flame cells (protonephridia)

osmoregulatory and excretory cells

"Turbellaria"

flatworm, uses chemoreceptors to find prey

Clade Trematoda

parasitic flukes (flatworms), uses hooks and suckers, monoecious

liver fluke life cycle

sexual adult stage in humans, asexual larval stage in snails

Clade Cestoda

flatworm, parasitic, microvilli for absorption, have scolex and proglottids

scolex (tapeworm)

posessed hooks and suckers for attachment only

proglottids (tapeworm)

segments that contain gonads

Clade Rotifera

pseudocoelomate, complete digestive tract

rotifer: corona

enables locomotion, collects food

rotifer: mastax

grind food

rotifer: foot

attach to substrate

Clade Bryozoa

moss animals, coelomate, colonies of interconnected zooids

bryozoa: funiculus

connects the zooids

bryozoa: lophophore

ciliated crown of tentacles surrounding mouth

Clade Brachiopoda

lamp shells, coelomates, dorsal and ventral shell

Clade Nematoda

in Clade Ecdysozoa, roundworms, pseudocoelomate, bilateral symmetry, complete digestive system, hydrostatic skeleton, dioecious, longitudinal muscles only

how to determine Ascaris sex

female: both ends straight, two reproductive strings inside

male: posterior hook, one reproductive string

ascaris cross section

female has uterus filled with eggs, male has many testes