Dogboy

Mollusks, arthropods and echinoderms.
Arthropods have many characteristics and this is some of them;
* Largest and most diverse group of animals
* Have jointed appendages, claws, legs, andantennae
* Have an exoskeleton to protect, support, and reduce water loss
* The exoskeleton must be shed, because it doesn't grow with the animal
* Have bilateral symmetry and segmentedbodies
An is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages, this Arthropods' primary internal cavity is a hemocoel, which accommodates theirinternal organs and through which their blood circulates; they have open circulatory systems.

Mollusks as arthropods Mollusks also have many characteristics like:
* They have a soft body,which gives them the name Molluscus, meaning soft
* They have either an internal or external shell
* They have a mantle, which is a tissue that covers the body mass of a mollusk        
* Theyhave a muscular foot or tentacles as in the case with squid or octopus
* Many have a radulla, which is a tonguelike toothed organ
Mollusks were among the first inhabitants of the Earth. Fossilsof mollusks have been found in rocks and date back over 500 million years. Mollusk fossils are usually well preserved because of their hard shell.Most mollusks have a soft, skin-like organ coveredwith a hard outside shell. Some mollusks live on land, such as the snail and slug. Other mollusks live in water, such as the oyster, mussel, clam, squid and octopus.

Echinoderms area phylum of marine animals. The adults are recognized easily by their (usually five-point) radial symmetry, and include such well known animals as sea stars, sea urchins, sand dollars, and sea cucumbers. Echinoderms arefound at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 70,000 living species.

CHAPTER 8
Sponges are animals of the phylum. They are multicellular...