Topic 22 Lophotrochozoa Flashcards
Mesoderm forms
muscles and most internal organs
Most animals are ___ symmetrical - clade ____
bilaterally, Bilateria
Most bilaterians have a coelom and a digestive track with __ openings
two
Bilaterians are strongly differentiated along _____ axis
anterior-posterior
Bilaterians have varying degrees of _____ (differentiation of head region)
cephalization
basal phylum of bilaterians
acoela
Phylum Acoela characteristics
flattened body,no brain or body cavity, have a mouth
Clade lophotorochozoa
clade defined by molecular phylogeny, and include: flatworms, annelids, etc
Phylum Platyhelminthes
known as free-living phabditophora, live in fresh-water and prey on smaller animals, one opening for mouth (spit food back out after eating), can reproduce sexually or asexually
parasitic rhabditophorans include
trematodes and tapeworms (lack digestive system and absorb nutrients from host)
Tapeworm body components
scolex (suckers and hooks for attaching to host) and segments that contain sex organs (proglottids)
Phylum rotifera
tiny animals that inhibit fresh and marine waters
Rotifers charachteritics
reproduce sexually and asexually, feed on microorganisms suspended in water, and have a complete digestive track
Ectoprocts and Brachiopods have
a fan of ciliated tentacles surrounding mouth, coelom, aquatic organisms, sessile
Ectoprocts
sessile colonial animals, most enclosed in a hard exoskeleton, suspension feeders using a retractable lophophore
Brachiopods
suspension feeders using paired lophophores, most attach to the seafloor, have a complete gus + anal opening
Trochozoa includes:
Annelida, Mollusca (snails, squid, clams)
Trochozoans share patterns of
early embryonic development, including a microscopic motile trochophore larvae
Trochozoans cilia
cilia control movement (swimming) and bring food towards the mouth, cilia bands is a sensory plate
Phylum Mollusca includes:
slugs, oysters, and clams, octopus, and squids
Mollusks are soft-bodied but are protected by s
hard shell
Mollusc body plan main parts
muscular ventral foot used for movement, visceral mass above the foot that contains internal organs, a mantle ( thin layer of tissue that secreted the shell), it is NOT segmented
Characteristics of mollusca
gills (within mantle cavity used for gas exchange), feeding using rasp-like radula, have an open circulatory system, most have separate sexes, life cycle includes a ciliated trochophore larval stage
4 major classes of molluscs
polyplacophora, gastropoda, bivalvia, cephalopoda
Phylum Annelida
segmented worms (repeated units of internal/external anatomy separated by septa)
Two major clades of annalids
errantia and sedentaria
Annelids Characteristics
segmented bodies: many repeated units separated by internal portions called septa
coelom: body cavity lined with tissue and is fluid filled cavity which functions as a hydrostatic skeleton
cephalization: well developed mouth and brain
closed circulatory system (blood in vessels)
