Invertebrates (Lophotrochozoan) (E1)

Question 1

Lophotrochozoan

Answer 1

bilateral symmetry

Question 2

Platyhelminthes (Flatworms)

Answer 2

• bilateral symmetry, acoelomates, flat body shape, no circulatory system, one gastrovascular opening, hermaphrodite
• Free-living - planarians, not parasites
  1) Trematodes - blood flukes, parasites, intermediate host
  2) Tapeworms - taenia, parasites, no gastrovascular cavity

Question 3

Mollusca

Answer 3

muscular foot used for movement, visceral mass (houses organs), mantle lays over visceral mass, secretes a shell
1) Chiton - unsegmented, shell made of eight plates, the foot is used to stick to rocks
2) Gastropods - snails and slugs, spiral shells, eyes at the tips of tentacles in heads, foot spans whole body, used to move
3) Bivalves - clams, oysters, mussels, scallops, shells made of two halves, no head, the foot moves the shell

Question 4

Cephalopods

Answer 4

• octopuses, squids closed circulatory system
• The foot is a current siphon that intakes water, used to jet out and move
• Well-developed sensory organs and complex brain

Question 5

Annelids

Answer 5

segmented body, coelomates, round shape, bilateral symmetry
1) Errantian - mobile, well-developed jaws and sensory organs, each segment has paddles (parapodia)
2) Sedentaria - less mobile than errantian, burrow through sediments
- Leeches - teeth cut the skin of the host, secretes anesthetics and anticlotting agents
3) Earthworms - eat soil, hermaphrodites, mouth and anus
- Can reproduce sexually, and asexually (fragmentation and regeneration)