Invertebrate | Definition, Characteristics, Examples, Facts

What are Invertebrates?

Invertebrates are animals that have no backbone, also known as vertebrae or spinal bones.

How are Invertebrates classified?

Invertebrates as a group do not have a specific taxonomy. Since vertebrates are classified under the vertebrate subphylum, invertebrates are any other animals classified outside this class.

Are there a lot of Invertebrate Species?

Mammals, amphibians, reptiles, fish, and birds all have vertebrae. It may seem like you know a lot of animals, but all of these animals make up less than 4% of the total animal species. This means that more than 96% of all animals on Earth are invertebrates.

What are some Invertebrate Animals?

Marine Invertebrates – There are many interesting types of marine animals that are invertebrates. These include sponges, corals, jellyfish, sea anemones, and starfish.

Mollusks – Mollusks whose mollusks are covered by an outer layer called the mantle. Many mollusks live inside the shell, but not all. Some examples of mollusks include squid, snails, slugs, octopuses, and oysters.

Crustaceans – Crustaceans are a type of arthropod, which means they have articulated legs. They also have an exoskeleton (their bones are on the outside like a shell). Some examples of shellfish are crabs, lobsters, shrimp, and oysters.

Worms – The term “worm” is not a scientific word, but is often used to refer to invertebrates, without legs. Worms can live in soil, water or even inside other animals as parasites. Some examples include tapeworms, leeches, and earthworms.

Insects – Insects are part of the largest animal phylum on Earth, the arthropods. There are more than a million species of insects, including animals such as grasshoppers, dragonflies, yellow jackets, butterflies, and mantises.

Spiders, centipedes, and scorpions – These animals are all arthropods. Spiders and scorpions are spiders because they have eight legs. Millipedes and centipedes are multi-legged and multi-legged species. Some myriapods have up to 750 legs. Some examples of species include the tarantula and the black widow spider, both of which are spiders.

Big and Small Invertebrates

The largest invertebrate is the giant squid. It can reach over 40 feet in length and weigh over 1,000 pounds. The longest invertebrate is the ribbon worm that can grow up to 180 feet long. The smallest invertebrates are rotifers, or wheel animals, which can be as small as 50 µm. Too small to be seen with your eyes alone.

Interesting Facts about Invertebrates

About 23% of all marine life is molluscs.

The only hard part on the octopus’ body is the beak that hooks at the end of its tentacles.

Some invertebrates, such as echinoderms, do not have heads.

There are probably millions of invertebrates living in your home right now. These are called ticks and you cannot see them.

When a crustacean grows out of its shell, it loses that shell and grows a new one.

Lobster, crab and shrimp all have 10 legs. Both front legs have claws that they can use to grab food and fend off predators.

Some mother scorpions protect their young by carrying them on their backs.

Centipedes are carnivores that eat insects and worms. They have a venomous bite to help them kill their prey. The millipede is a herbivore that eats plants and decaying matter.