They are so vast that they can be found in any ocean in the world, from the warm tropical waters to the cold artic and antarctic waters. Invertebrates can also be found at great depths of the ocean with no light source, and so are not dependent on the sun energy; they instead get their energy in the form of heat and chemicals from submarine volcanic activity.

Invertebrates can be broken up into different groups these being CRUSTACEA and MOLLUSCA.

Crustacea or crustaceans are marine animals such as crabs, shrimps, prawns, barnacles. , and crayfish.

Mollusca or mollusces are shell fish such as cockles, oysters scallops,mussels sea slugs, sea hares, octopus, and squid.

Some typical examples of invertebrates are bacteria, sponges, molluscs, crabs, shrimps, prawns, filter feeding worms, coral (polyps), jellyfish, anemone,flatworms, nudibranchs, cuttlefish, crayfish, octopus, squids, sea eggs or sea urchins, sea squirts, and starfish, etc.