Diversity of Life - MOLLUSCA- (snails, slugs, clams, octopi)

Porifera

Cnidaria Ctenophora Platyhelminthes Rotifera

Nematoda Nemertea Mollusca Annelida Arthropoda Bryozoa

Phoronida Brachiopoda Echinodermata Chordata

No true tissues

radial symmetry diploblastic

true tissues

Acoelomates

Deuterostomes

Bilateral symmetry triploblastic

Body cavity

Protostomes

Lophophorate phyla

Pseudocoelomates

Coelomates

A Phylogeny of the Animal Phyla

Mollusca - snails, slugs, clams, octopi

Mollusca - What makes them all molluscs?

Molluscs • triploblastic • soft bodied animals • protected by or possess a hard calcium carbonate shell

Mollusca - How do you build a mollusc?

Remember the standard coelomate body plan.

Step 2 - Put a fold of tissue dorsally

Step 1 - Expand the lower body wall

Step 3 - Put a shell over top

Mollusca - How do you build a mollusc?

End view Side view

Coelom

Shell

Mantle

Foot

Mollusca - How do you build a mollusc?

End view Side view

Coelom

Shell

Mantle

Foot

Visceral Mass Foot

Mollusca - How do you build a mollusc?

This is the basic body plan from which all molluscs are derived.

Mollusca - Classification

1. Gastropoda - snails and slugs If you lift and twist the shell + visceral mass in the basic body plan, you make a snail.

Mollusca - Classification

2. Bivalvia - clams, oysters, mussels If you grow the shell down both sides of the body, you make a mussel or clam.

Mollusca - Classification

2. Cephalopoda - octopus and squid If you lose the shell and pull the foot down to make a series of tentacles, you make a squid or octopus.

Molluscan Groups

Class – Polyplacophora – the chitons

Molluscan Groups

Class – Gastropoda

Molluscan Groups

Class – Gastropoda

Molluscan Groups

Class – Bivalvia (Pelecypoda)

Molluscan Groups

Class Cephalopoda

Taxa we have looked at so far

Phylum Class Order

Porifera Calcarea

Demospongia

Hexactinellida

Platyhelminthes Turbellaria (free-living)

Trematoda (flukes)

Cestoda (tapeworms)

Mollusca Polyplacophora (chitons)

Gastropoda (snails,slugs)

Bivalvia (clams, oysters)

Cephalopoda (octopus, squid)