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As the name suggests, invertebrates are animals that do not possess a vertebral column (spine or backbone). With just one feature to define them all, this makes for a huge group of animals: insects, snails, worms, crabs, octopuses and many, many more. Invertebrates make up 97% of all living animals on the earth, and to say this is a wildly diverse grouping is an understatement. Consider the adult female Dolania americana (mayfly) who lives for only five minutes as an adult… or the Turritopsis dohrnii (jellyfish), who can – at least theoretically – live for 500+ billion years!

Featured Invertebrates


“Clam” is an informal name that refers to bivalves (such as oysters, scallops, mussels, cockles, clams, and numerous…
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Comb jelly

This phylum of animals inhabits marine waters worldwide. They are named for their distinctive rows of cilia, or combs,…
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These marine invertebrates are known for the dazzling calcified colonies they create as they multiply and grow. Each colony…
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Crinoids, aptly nicknamed “feather stars”, can inhabit a wide range of marine environments and, judging by the fossil…
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This very large group of arthropods includes familiar animals such as shrimp, crabs, lobsters, crayfish, and barnacles.…
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These tube shaped, segmented worms commonly live in the soil and feed on both live and dead organic matter. Earthworms…
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The structure of flatworms (flat) reflects their physiology – they have no body cavity other than a gut in most cases…
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Hydras make up a genus of tiny (up to 10 mm long), tentacle, aquatic, predatory animals that are commonly found in unpolluted…
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This class of invertebrates has a chitinous skeleton, a three part body (consisting of a head, thorax, and abdomen), six…
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Jellyfish are typically free-swimming animals consisting of a gelatinous, inverted-umbrella body form (the bell) with…
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While similar in some ways to earthworms, leeches differ in other distinct ways – for example, leeches do not have bristles…
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Mantis Shrimp

The mantis shrimp is not actually a shrimp, but a different kind of crustacean of the order Stomatopoda, known for its…
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Mosquitos are a family of small flies (the name “Mosquito” literally means “Small Fly” in Spanish)…
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This family of polychaete worms contains about 500 mostly marine species. They can be found in all water depths – hiding…
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These microscopic and near-microscopic pseudocoelomates are common in freshwater environments all over the world (and…
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This diverse phylum is made up of an estimated 1 million species of roundworms, many of which are parasitic. Nematodes…
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Sea anemones

These water dwelling, carnivorous animals are named for a type of flower, no doubt owing to their often colorful flower-like…
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Sea cucumbers
(Actinopyga echinites)

These tubular echinoderms can be found in oceans all over the world – in some deep sea environments they can be found…
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Sea stars

Also known as starfish, these echinoderms are found on the sea floors of all the world’s oceans from the equatorial…
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Sea urchins

These small, spiny, globular animals inhabit all the oceans of the world and can survive in shallow intertidal zones,…
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Snails and slugs

“Snail” is a common name applied to most members of the class “Gastropoda” that have a coiled shell that is big…
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Spiders and other arachnids

The Arachnid class is comprised of over 100,000 described species and includes such familiar organisms as spiders, scorpions,…
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Sponges are aquatic, multicellular organisms whose body structure is full of holes and channels that allow water to circulate…
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Squids, octopi, nautili & cuttlefish

These ocean dwelling animals are characterized by bilateral body symmetry, a prominent head, and a set of arms, or tentacles.…
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“Water bears” or “moss piglets” are tiny (~0.5 mm), aquatic, segmented animals that are able to withstand extreme…
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Ticks are small, blood-sucking arachnids of the order Parasitiformes, with over 900 known species.

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Interesting Facts

Learning about animals, you can discover many fascinating, even beautiful facts… but there are also things that can give you nightmares! Enter the strepsiptera (“twisted-wing parasite”). The adult female has no limbs, wings, or mouth – she simply lives in and feeds off her host (typically a wasp). When it becomes time to mate, she protrudes part of her abdomen from between the plates of her host and uses mind control to get the wasp to fly off to nearby males. The males have wings, and fly around for about five hours before dying, their only purpose seeking out females to mate with. After the female is impregnated, her own young grow and consume her. Once there is nothing left to eat, they leave their host wasp, infiltrate the wasp nest's nursery, then latch on to larvae to create their own “zombie wasp” host and continue the grisly cycle!


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