Lec 2: Invertebrates; worms

Question 1

Clade Lophotrochozoa

Answer 1

members have bilateral symmetry, lophophore (feeding structure used for suspension feeding) trochophore ( larval form)

Question 2

phylum platyhelminthes

Answer 2

flat worms, some free living, some parasitic. Bilateral symmetry, triploblastic, acoelomate, closed gut (GVC) gas exchange = passive, thru skin. Cephalization = sensory/nervous tissue (the eye spots) and protonephridia = osmotic balance of salt content in flatworm

Question 3

Class Turbellaria (Phylum Platyhelminthes)

Answer 3

Free living flat worms, cillia for movement, found in aquatic environments, can regenerate body parts

Question 4

Class trematoda (Phylum Platyhelminthes)

Answer 4

Flukes, parasitic, loss of cephalization due to being parasitic, have oral and ventral sucker to attach to host, definitive host = where sexual reproduction occurs, most have 3 hosts (snail to infected water (both intermediate hosts) to human)

Question 5

Class cestoda (Phylum Platyhelminthes)

Answer 5

Tapeworms, repeating units = proglottids, scolex = attachment to host (suckers on head) Each proglottid has both female/male reproductive organs, can self/cross fertilize w other proglottids

Question 6

Phylum Syndermata

Answer 6

Rotifers (microscopic aquatic invertebrate), pseudocoelomate, bilateral, triploblastic, parthenogenesis (populations almost exclusively female, environmental stress = production of males, more sexual reproduction

Question 7

Clade Ecdysozoa

Answer 7

Have exoskeleton made of chitin

Question 8

Phylum nematoda

Answer 8

roundworms/pinworms/hookworms, unsegmented, bilateral, triploblastic, pseudocoelomate, open gut, cause trichinosis (trichinella)

Question 10

Schistosomiasis life cycle

Answer 10

Blood fluke lays egg in human intestine, if it reaches water becomes miracidium (free swimming larvae) to find snail. Then infects snail to form sporocysts to undergo asexual reproduction, developing cercariae which are free swimming and they leave the snail in water to find human. Infects human through cuts in skin in infected water, penetrate skin, lose tail, and transform into schistosomula. Finally enter bloodstream and go to liver to mature, undergoes sexual reproduction, lay eggs, cycle repeats