INVERTEBRATES: animals that do not have backbones. (radial symmetry …
INVERTEBRATES: animals that do not have backbones.
— have soft, unsegmented bodies, often protected by a hard shel; — mollusks have a thin layer of tissue called a mantle that covers their internal organs and a "foot"
Gastropods , such as snails, have a single shell or no shell at all, and a distinct head.
Bivalves, such as clams, have a two shells and a simple nervous system.
Cephalopods may have a external, or internal shell, some have none at all. They have a good vision and large brains.
— have internal skeletons called endoskeletons ; — and a system of fluid- filled tubes to move around and obtain food and oxygen; — have radial symmetry
— have stinging cells; — take food into a central body cavity; — have radial symmetry; — they lack organs, but do have some tissue
— asymmetrical; — they have some specialised cells, but no tissue or organs; — take food into their bodies to get their needed energy
— have bilateral symmetry; — have tissue, organs, and organ systems; — flat, soft bodies, with "eyes" to detect light; — two body openings: a mouth and an anus; — bodies made up of segments; — have a brain to detect food and predators
— have hard outer coverings, segmented bodies; — they have jointed appendages (legs, wings, antennae); — their skeleton is called an exoskeleton. which is sometimes she and replaced
Crustaceans, a type of arthropod, include animals such as crabs.
Arachnids, another group, includes animals such as spiders.
A a third group includes the centipedes, millipedes, and other insects.