Giant Isopod

The giant isopod is one of the largest isopods in the world, and it can be any one of the 20 species of big isopods. These creatures are found in the cold and deep waters of the Pacific, Indian, and Atlantic oceans. Giant isopods are closely related to decapods such as crabs and shrimps, which are found in the Bathynomus genus.

It is one of the largest crustaceans and a member of the isopod family. They are terrestrial crustaceans, much like the pill bugs. The resemblance between giant isopods and pill bugs is uncanny. These isopods are the ocean’s clean-up crew, and their large size is the result of the sea gigantism phenomenon.

3 Facts About Giant Isopods

• Giant isopods do not have a spine, which makes them invertebrates.
• They are the largest isopods, growing up to 20 inches (50 cm) in size.
• They do not live on land and instead inhabit three main oceans around the world.

Species, Types, and Scientific Name

There are nearly 20 different species, all in the Bathynomus genus. All of these isopods have the abyssal deep-sea gigantism gene, a definition from the French zoologist Alphonse Milne-Edwards. Let’s look at the most popular species.

• Bathynomus affinis
• Bathynomus giganteus — The largest of the giant isopods.
• Bathynomus brucei
• Bathynomus bruscai
• Bathynomus crosnieri

Appearance: How To Identify Giant Isopods

Giant isopods are different than your typical isopod because they grow quite large. Their size is the result of abyssal gigantism, which makes them grow between 6.7 and 19.7 inches in size for super-giant isopods, and the giant isopods reach 6 inches in size. The Bathynomus giganteus is the largest of the species, reaching up to about 20 inches (50 cm) in size. The morphology resembles that of the woodlouse and pill bug. They have calcareous exoskeletons made of overlapping segments.

They have large compound eyes that contain 4,000 facets and are separated on their head. The giant isopod has two pairs of antennae, and its first shell segments are fused to the head, which allows it to curl up into a ball that leaves its shell exposed as a form of protection against predators.

It possesses seven pairs of legs, two of which are used for moving food to their four jaws, and the others for movement in the water. Ranging in color from pink to lilac, they have a set of flat respiratory structures, which act as gills so that they can breathe underwater.

Habitat: Where To Find Giant Isopods

You will find them off the east coast of Australia, the Gulf of Mexico, Brazil, and the Caribbean in the West Atlantic. Five species of giant isopods are found off the coast of Australia, the Atlantic, Pacific, and Indian oceans.

They inhabit deep, cold waters, ranging from 550 to 7,020 feet below the surface. They spend their time at the bottom of the ocean floor, made of mud or clay. These marine creatures do not live on land, and they crawl around rocks, substrate, and aquatic vegetation in search of food that they forage for.

Diet: What Do Giant Isopods Eat?

They are foragers, which means they search for their food throughout the day. They are carnivores and scavengers, and their diet consists of live and dead animals such as whale carcasses, crab, fish, squid, sea sponges, and shrimp. Some will also eat trawl catches.

This makes them one of the ocean’s most beneficial cleanup crews, and similar in eating habits to the terrestrial isopods. Some in the southern Gulf of Mexico have large quantities of plastic in their stomach. This likely fell to the bottom of the ocean and was eaten by their powerful jaws.

They locate their prey via chemoreception or mechanoreception, allowing them to respond to mechanical pressure to sense their food. These creatures hunt in groups, which allows them to consume a large amount of food at a time and makes them quick to finish off a large dying or dead whale that has sunk to the bottom of the ocean.