The “soft bodied” animals Mollusks The “soft bodied” animals

Characteristics Visceral Mass- contains the organs- the “soft bodied” part Mantle- makes a shell in most organisms. Foot- muscular lower part used for movement Shell in most Radula - tongue-like structure, sharp Head area- that contains the brain and sense organs Systems: digestive, muscle, nervous, circulatory, reproductive, respiratory (gills)

Examples Gastropod (also called univalves)- “stomach-foot”-- looks like the crawl on their “stomach” Open circulatory system Snails Slugs

Examples Bivalves- “two door ways”- Have 2 parts to their shell Open circulatory system Yellow nudibranch Giant clam

Examples Cephalopods- the “head-footed” mollusks Closed circulatory system Most advanced nervous system (they can learn!) Atlantic squid Octopus Nautilus

Digestive system Food enters through the mouth and goes through the esophagus, to the stomach, and then intestines. Wastes leave through the anus.

Respiratory system

Nervous system and sense structures Gastropods: eye spots (on stalks at base of tentacles or on tentacles) and chemical sensors in tentacles Bivalves: photoreceptor and vibration cells Cephalopods: Best developed brain of all invertebrates- can detect light, vibrations, chemicals Eye of snail suckers on octopus tentacles

Muscle system The muscular foot Gastropods Bivalves Cephalopod

Mollusk defenses Changing color. Cephalopods have an amazing ability to change color very rapidly. Chromatophores, pigment-filled bags, are found in the skin and expand and contract to reveal or conceal small dots of color.