Invertebrates

One species in the phylum Mollusca is a clam. The clam lives mainly in the ocean, in colonies called beds. It eats plankton, and moves by using a single foot to burrow through the sand.

The clam breathes the same way most marine animals do- by getting its oxygen from the water. It ingests food by using cilia to retain food from the passing water and to carry it into their mouths. Lastly, it reproduces when females expel eggs into the surrounding water, and males fertilize them.

Vocabulary:

1. Radula- a toothed tongue-like appendage
2. Gills-underwater breathing apparatus used by water-dwelling animals- mostly fish, but some others
3. Open circulatory system- system of circulation in which blood is not enclosed in tubes, but flows straight from the gills, to the heart, to tissues, and back to the gills
4. Closed circulatory system- system of circulation in which the blood is enclosed in tombs
5. Mantle- a tissue that protects the reproductive, excretive and digestive organs; and lines the nautilus' shell

1. Bivalves- Mussel
   Where it lives: underwater, in areas called "beds"
   What it eats: plankton
   How it moves: sessile
2. Gastropods- Periwinkle
   Where it lives: in the ocean
   What it eats: algae and seaweed
   How it moves: it expels a slimy trail, over which it moves on its single foot
3. Cephalopods- Squid
   Where it lives: in the ocean
   What it eats: fish
   How it moves: swims, using either tentacles or jet-propulsion

The starfish, also known as the sea-star, is one member of the Echinodermata phylum. It lives on the ocean floor, eats clams, and moves by  walking on the ocean floor by using its tube feet.

The starfish ingests its food by using suction to pick up its prey with the tube feet mentioned above. It circulates nutrients and waste around its body through vaccuum-filled tubes that food, oxygen, and excretory material travel in.

Like planarians, the starfish can regenerate lost limbs. (This proved to be a source of endless frustration to clam fisherman when the starfish were eating all of the clams in the area. In an attempt to destroy the predators the fisherman chopped the starfish into pieces, but the plan backfired when each chopped up piece regenerated into a new sea star, thoroughly defeating the fishermen's purpose.)

Vocabulary:

1. Water vascular system- a system of vaccum-filled internal tubes that carry food, oxygen, and wastes in an echinoderm.
2. Tube feet- cuplike structures for suction that help echinoderms to walk and to ingest their prey as well as walk onto land in some circumstances.
3. Spines- sharp rigid growths on the outside of an organism
4. Radial symmetry- the property of symmetry around a central axis that is exemplified in a starfish
5. Ray- A line from the center of a circle.