What
are
Invertebrates?
When thinking about “animals”, most people think of large, obvious beasts, like dogs, cows, cats and koalas. But most animals are much smaller, and they don’t have backbones like the one’s I’ve just mentioned. In fact, more than 95% of all animals are invertebrates!
Invertebrates live in all over the world, in a huge variety of habitats. Some live in the oceans, some in forests, some in deserts, and some even live inside other animals. You are likely to find invertebrates in your backyard, at the local park, in a stream, and perhaps even squashed on your windscreen! Try looking under a brick or stone in your garden; you’re likely to find a slater or two, and perhaps a spider or a millipede. Or leave on a light outside at night, it will attract many, many species of invertebrate animals.
There are a huge variety of invertebrate forms, including spiders, beetles, bugs, crabs, worms, slugs, snails, bees, flukes, sea stars, jellyfish and crustaceans. There is also a great variety of ways in which they get around; they swim, crawl, fly, walk, jump, dig, scuttle or just drift on ocean currents.
Most invertebrates are small, like ants and flies, but some can be larger, like crabs that have an external skeleton (an exoskeleton), and worms that can be many metres long. Giant squids are invertebrates, too, and they can grow over 10 metres long!
Invertebrates are important because:
- They help to fertilise plants (including human food plants)
- Many animals eat invertebrates (birds, reptiles, fish, frogs, mammals, other invertebrates). We also eat them (crabs, oysters snails, and squid is perhaps the world’s most underutilised protein resource). And we eat honey, the product of invertebrates.
- Many invertebrate populations can get out of control and be pests, but often the populations are controlled by other invertebrate species
- They are being used as sources of new pharmaceuticals and industrial chemicals
- We benefit psychologically from spending time in diverse natural environments (that include invertebrates)
The most diverse group of invertebrates are the insects. These animals have six legs and three main body parts, the head (where eyes and mouthparts are), the thorax (where wings and legs attach), and the abdomen (where their vital organs are). The most diverse group of insects are the beetles. In fact, they represent over 25% of all identified animal species.