Question

Both annelids and mollusks have a true coelom. True False QUESTION 2 Select all the features that all mollusks share with each other. muscular foot mantle shell tlosed circulatory system - complex eye radula QUESTION 3 Select all the organisms that have a segmented body plan in this list: nematode worms parasitic flukes -Snakes leeches polychaete worms earthworms QUESTION 4 Which phylum shares a common ancestor most recently with mollusks? Annelida Platyhelminthes Nematoda Arthropoda

Answer 1

1. True. Mollusks and annelids are invertibrates. Mollusks are normally shelled and annelids are segmented. Both of them have true coelom. True ceolom means body cavity with a complete lining.

2. Muscular foot- YES, Mantle (extension of body wall)- YES, shell- NO (most mollusks have shells. But some like squid, banana slug dont have shells), closed circulatory system - NO (mollusks have open circulatory system with the exception of class Cephalopoda), Complex eyes - NO (mollusks have wide varieties of eye morphology- from simple to very complex) radula - NO (most classes of mollusks have radula -structure of tiny teeth- with the exception of bivalves)

3. Phylum nematoda (round worms) have no segmentation , Parasitic flukes (trematodes) are not segmented, Snakes have segmented body plan, Leaches (Phylum Annelida) have segmented body plan, Polychaet worms (Annelids) have segmented body plans, Earthworms are segmented.

4. Phylum Annelida share common ancestor most recently with mollusks. Both of them have true coelom. Most of the mollusks are shelled and annelids are segmented. Platyhelminthes and Nematodes have no true ceolom. Arthropodes have hard exoskeleton.