When you ask someone to name an animal, most people will say a type of furry mammal, feathery bird or scaly reptile. However, did you know that most of the animals that live on Earth are actually invertebrates. But what are invertebrates?
What are invertebrates?
Invertebrates are creatures that do not have an internal jointed skeleton. Instead, many feature protective shells or exoskeletons whereas others simply have soft bodies. Invertebrates include a wide variety of animals such as microscopic worms, giant squid, scorpions, ants, snails and spiders. Altogether, these creatures make up at least 97% of all animals species on our planet.
Types of invertebrate
The animal kingdom can be broken down into 35 major groups of species, each of which is called a phylum. All but one of these phylum are made up of invertebrates. This includes sea sponges, mollusc (e.g. snails, clams and octopuses), cnidarians (e.g. corals, jellyfish and sea anemones) and arthropods (e.g. insects, crustaceans and arachnids). Arthropods make up the largest phylum and are animals that have tough external skeletons with jointed legs, which allow them to live both on land and in the water. Over 80% of all known animal species are arthropods. Most of them are insects.
Facts about invertebrates
Ladybirds have a very interesting and unique defence mechanism called reflex bleeding, in which they ooze a noxious yellow fluid from their joints.
Cnidarians (pronounced nidarian – the ‘c’ is silent) are aquatic, soft-bodied animals that are often equipped with stinging cells to catch prey.
Approximately 110,000 living species of mollusc have so far been scientifically described and named. The heaviest living mollusc is the giant clam – the largest ever discovered was 300kg.
Lobsters have the ability to grow another claw, leg or antenna if it loses one.
Snails don’t glide along on their bellies – the slimy underside they move on is actually referred to as their muscular foot.
The word cephalopod – the term used to describe octopuses and their relatives – means “head-foot” referring to how their limbs appear to be attached directly to their heads.