Snails, slugs, oysters, clams, Scallops & squids.

includes snails, clams, octopi and slugs

All mollusks share 6 Characteristics Body Cavity They have a true coelom, Though it is a small space Near the heart.

Most mollusks have Bilateral symmetry. They also have a 3 part body plan. These parts are the visceral Mass, mantle and foot.

All mollusks have organ systems For excretion, circulation, Respiration, digestion and Reproduction. Many mollusks have 1 or 2 shells That act as an exoskeleton. The shells are made of Calcium carbonate.

All mollusks, except for oysters, Have a radula. The radula is a tongue like organ That has thousands of teeth.

Mollusks are the only coelomates Without segmented bodies. Mollusks are the first to have Developed an efficient Excretory system. The nephridia is used to remove Liquid wastes.

Most mollusks have a 3 chambered heart and An open circulatory system.

Many mollusks have gills that Are used for respiration, Snails have a primitive lung. Reproduction Sexual External fertilization Some hermaphrodites Some oysters can switch sex

Mollusk Classes A. Class Gastropoda: Snails & Slugs –single shell (slugs lost it) –large foot on ventral side

Class Bivalvia: Clams, Mussels & Oysters two hinged shells filter feeders and benthic

foot used to burrow and anchor scallops “clap”

C. Class Cephalopoda: Squid & Octopus foot evolved into tentacles with suckers active marine predators jet propulsion radula is a beak

Segmented Worms

Annelid fossils have been found That are 530 million years old! Scientists think that annelids Evolved from the sea, where Most annelids are found. Their size varies from 1mm to More than 3m long!

No matter how long, All segments contain digestive, Excretory, circulatory, And muscles.

There is a cerebral ganglion, Or primitive brain, in one Of the first segments and is Connected to a nerve cord That runs along the bottom Of the worm.

They have septa, which are body Walls that separate segments.

They also have Setae, which are Bristles that Help traction as They crawl along.

Habitat Soil, saltwater and freshwater

Closed circulatory system

Respiratory System Gas exchange through body wall

Cuticle

Digestive System “Tube within a tube” digestive system Mouth Pharynx Esophagus Crop Gizzard Intestines Anus

Reproduction Hermaphrodites Sexual

Clitellum -- cocoon