Invertebrate



Invertebrate is a kind of animal that does not have a spinal column or backbone. It is the opposite of vertebrate, that means if an animal is not a vertebrate (fish, reptile, amphibian, bird, or mammal), it is an invertebrate.

The main phyla (groups) of invertebrate animals are:
 * Annelida: segmented worms
 * Arthropods: (arachnids, crustaceans, insects, and others);
 * Brachiopods: the lamp-shells.
 * Bryozoa: sea mats or moss animals (sometimes they look like corals)
 * Cnidarians: jellyfish, sea anemones, hydroids.
 * Echinoderms: starfish, sea urchins, sea cucumbers
 * Molluscs: (gastropods, cephalopods, bivalves and others);
 * Nematoda: roundworms
 * Porifera: sponges
 * Platyhelminthes: flatworms
 * Rotifers: tiny "wheel animals", which live in habitats such as pond water.

Insects and other arthropods have no bones, but they have a skeleton on the outside of their bodies, called an exoskeleton.

There are 18 more groups of invertebrates, mostly minor: see List of animal phyla.