Phylum Mollusk Snails, Clams, Squids, etc.

Trochophore Larvae – the stage of organism after gametes have been fertilized

Why they are Mollusks

Classification of Mollusks unsegmented soft body internal or external shell trochophore larva mantle – thin, delicate tissue layer lining muscular foot visceral mass

Feeding herbivores, carnivores, filter feeders, detritus feeders, parasites herbivory and predation (eg. snails, slugs)  radula tongue-like structure with hundred of tiny teeth Filter-feeders (eg. clams, scallops)  gills (in mantle cavity) filter food from water Octopus eating Crab

Respiration Aquatic mollusks (eg.sea slugs, squid)  Gills in mantle cavity Land mollusks (eg. land snails and slugs)  modified mantle cavity lined with blood vessels

Internal Transport oxygen and nutrients are transported by blood open circulatory system  no blood vessels, have sinuses  for slow moving animals closed circulatory system  blood travel in blood vessels  fast moving animals

Excretion undigested solid waste (feces) through anus nitrogen-containing waste removed from the blood by nephridia

Response varies greatly between classes less active mollusks  small ganglia near mouth  nerve cords  simple sense organs active mollusks  well-developed brain

Reproduction separate sexes external fertilization release eggs and sperm into open water Exceptions: cephalopods and some snails– internal fertilization oysters can change sex

Snail Courtship

Mating Snail Sperm Darts

Classes within the Phylum 7 classes Class Gastropods  eg. snails and slugs Class Bivalvia  eg. clams, oysters and scallops Class Cephalopods  eg. octopi and squids Survival Game