An animal without a backbone, the invertebrates comprise over 99% of the 15 million or more animal species on the planet.
Some believe there may well be over 100 million species of invertebrate and that we have so far only seen the tip of the iceberg. It is thought that invertebrates in some form or another have inhabited the planet for over 1 billion years. Invertebrates include insects, spiders, sponges, snails, octopuses, clams, squid, jellyfish, anemones, corals, starfish, sea urchins, worms - the list could go on!
Most invertebrates are relatively short-lived animals. Some live for less than 24 hours whereas other species such as some clams are believed to live for over 200 years.