Xenacoelomorpha, platyhelminthes, etc. EXAM 1

chapter 14

how many germ layer?

three- triploblastic

cephlilization

having all sensory structures in one area- having a head

protostome

first opening is mouth

dueterostome

first opening is anus

lophotrochozoa

bilaterally symmetrical, protostome invertebrates within the clade Spiralia. They are defined by sharing either a lophophore (a crown of ciliated feeding tentacles) or a trochophore larva (a free-swimming larva with ciliary bands) during their life cycle

Ecdysozoa

many have cuticle that is molted

Phylum Platyhelminthes

flatworms, free living or parasitic.

SYNCYTIAL tegument or neodermis

outer layer that protects internal parasites from the defense of the host. resistant to immune system of host.

class turbellarians

most have cellular, ciliated epidermis. contains rod- shaped rhabdites. most are free living. mouth on ventral side. movement with muscular and cilial movement. can swim if very small.

pharynx

a versatile muscular tube connecting the mouth to the gut, functioning as the primary organ for feeding and waste expulsion

protonephridia

gets rid of extra water, can do some excretion of wasteo

osmoregulation

regulating internal water and electrolyte balance (osmotic pressure) to maintain homeostasis against varying environmental conditions.

flame cell

beating flagella moves fluid down collecting ducts for expulsion

ocelli

eye spots that are light sensitive

tactile cells

touch sensitive cells

class trematoda

all parasitic worms, endoparasites,

trematodes- subclass digena

first intermediate host is mollusc. definitive host is vertebrate. reproduce sexually in host

digenaen life cycle

egg leaves host in waste - hatches - larval stage (miracidium)- enters snail - sporocyst - asexual reproduction - rediae - cercariae - leaves snail - metacercaria - eaten by vertebrate host - sexually producing adult stage.

miracidium

free swimming larval stage, with ciliare

sporocyst

life-cycle stage for certain parasites. encapsulated, spore-like structures essential for transmission

rediae

They arise from sporocysts and produce either daughter rediae or cercariae. develop within a molluscan host.

cercariae

these burrow out of a snail. free-swimming, tadpole-shaped larval stage of trematode parasites (flukes)

metacercariae

adult paracite. infective larval stage of digenetic trematodes (flukes). The final hosts are human.

clonorchis sinensis

human liver fluke. requires snail. 1 miracidium can produce 250000 cercariae. transfer to fish, eaten by human.

blood fluke- schistosoma

males have gynecophoric canal. no rediae or metacercariae stage.

class cestoda

tapeworms- long flat body with scolex. holdfast structure with suckers and hooks. the only sensory organ is a modified cilia. most do little harm to host.

scolex

1. the anterior end of a tapeworm, bearing suckers and hooks for attachment.

proglottids

reproductive segments that make up the body (strobila) of an adult tapeworm. It is not true segmentation, just replication.

strobila

main body (proglottid chain)

germinative zone

region located immediately behind the scolex (head) that acts as the primary proliferative center for budding new proglottids.

Taenia saginata

Beef tapeworm. Adults live in human intestine. Juveniles in intermuscular tissue of cattle. humans eat undercooked beef, and the cyst wall dissolves.

oncospheres

shelled larvae

cysticerci (tape worm)

larval stage of the tapeworm, appearing as 5–15 mm fluid-filled sacs (bladder worms) containing a single, invaginated scolex.

Phylum Rotifera

ciliated crown, corona, beats like a rotating wheel. mostly benthic. some part of meiofauna. some epizoic.

corona

ciliated crown, where the mouth is located

meiofauna

Meiobenthos, also called meiofauna, are small benthic invertebrates that live in marine or freshwater environments, or both.

epizoic

growing or living nonparasitically on the exterior of a living animal.

Mastax

muscular pharynx equipped with hard jaws (trophi) in a rotifer

trophi

hard jaws that are constantly movving in a rotifer

class monogononta

males only present for a few weeks. mostly diploid amictic eggs.

amictic eggs

diploid, asexual eggs produced by female rotifers that develop directly into females without fertilization.

mixis stimulus

an environmental signal that triggers a switch from asexual to sexual reproduction in monogonont rotifers.

platyhelminthes 4 classes

Turbellaria- The nice worms. No parasites, all free living.

Tremetoda- flukes all endoparasitic

Monogenea- flukes ectoparasitic

Cestoda- tapeworm

Rotifer classes

Seisonidea

Bdelloidea

Monogononta