What is an Invertebrate?

An invertebrate is an animal that does NOT have a backbone or in fact, any bones at all! Invertebrates make up over 98% of ALL animal life and can be found living in every habitat found on earth, from the deep ocean and polar ice caps, to even the driest deserts. Every living creature on earth usually depends on several invertebrate species to survive.

Invertebrates include animals such as:

• Jellyfish
• Corals
• Sea Sponges
• Worms
• Leeches
• Snails and slugs
• Octopus, Squid, Cuttlefish and Nautilus
• Sea Squirts
• Sea Cucumber
• Crabs, Crayfish and Lobsters
• Starfish
• Sea Urchins
• Centipedes and Millipedes
• Spiders and other arachnids

Invertebrates usually have a hard shell or similar on the outside of their bodies. We call this an ‘exoskeleton’. In some invertebrates like lobsters, the exoskeleton is quite hard like a suit of armour, however some invertebrates don’t possess an exoskeleton at all. Animals such as worms and slugs have adapted to living without an exoskeleton by living in habitats where they won’t dry out or be at risk of attack as well as secreting slimy substances in order to protect them in several ways. Some animals such as snails, have a shell in which they can retreat if the weather gets too hot and dry or if a predator tries to attack them.

Other animals, such as fish, amphibians, reptiles, mammals and birds have a backbone and a skeleton inside their bodies. We call these animals ‘vertebrates’.