There are a lot of cute animals swimming around in the ocean. Looking at photos online of a dumbo octopus or sea turtle is always a heart-warming experience. If you’ve never seen a picture of an axolotl, well, you’re welcome.
Then you have some underwater animals that are just plain terrifying. Great white sharks can probably eat you in a single bite. Giant squids are basically monsters out of an old fisherman’s tale, except real. But then there are completely harmless animals like the giant isopod that are terrifying simply because they look like giant sea cockroaches from hell.
Back in 2018, a team of Indonesian researchers off the coast of Java found a particularly nightmare-inducing creature lurking in the deep sea. The specific species of isopod had yet to be discovered, and they gave it the scientific name Bathynomus raksasa.
However, this species is not alone. Collectively, there are 20 known species of giant isopod, all of which have been nicknamed “sea cockroaches,” and with good reason. If you already had thalassophobia (fear of the ocean), seeing these pictures of the giant isopods certainly isn’t going to help.
While these horrifying creatures only live in the deep ocean and most likely will never make their way to a beach, just knowing that they’re out there is enough to make me never want to sleep again.
We humans tend to fear the unknown, which is probably why thalassophobia is so common. That dark veil of the ocean water allows our imaginations to run wild with what kind of horrors could be lurking beneath it.
In hopes of overcoming our fear of these sea cockroaches, let’s try to get to know them a little bit. Perhaps by the end of this article, you might even feel a slight sympathy or affection for these hideous sea cockroaches. (Hey, they didn’t choose to be that ugly). Or maybe you’ll have nightmares for weeks of being trapped in the deep ocean surrounded by these horrifying creatures. There’s only one way to find out.
What Are These Sea Cockroaches?
These animals, which have been nicknamed sea cockroaches, are actually known as giant isopods. There are 20 known species, all of which belong to the class Malacostraca, which also contains better-known animals such as crabs, lobsters, krill, and shrimp.
While these giant isopods have been nicknamed “sea cockroach,” they actually bear far more resemblance to one terrestrial member of Malacostraca, the common woodlouse or “pill bug.” Cockroaches and giant isopods are in the same phylum, Arthropoda, they are not part of the same Linnean class. So, have these poor giant isopods been treated unfairly? Would we think them so disgusting if they were referred to as “sea pill bugs” instead?
A giant isopod is any member of the genus Bathynomus, which was described in 1879 by French zoologist Alphonse Milne-Edwards after a specimen was collected from the Gulf of Mexico by his colleague Alexander Agassiz.
This discovery was extremely important to our understanding of the deep ocean, as the prevailing theory at the time was that the deep ocean was entirely lifeless. Agassiz’s discovery of the giant isopod proved that life could indeed survive in the conditions of the deep ocean.
Since their discovery, humanity has become far more familiar with these giant isopods. We’ve studied their features closely and even found fossils of giant isopods from the Miocene and Pliocene in Japan.
Giant isopods live in the Atlantic waters from the state of Georgia to Brazil, though only the species Bathynomus giganteus has ever been recorded off the coast of the United States. But if you’re living in the United States and you’re breathing a sigh of relief right now, hold up. Bathynomus giganteus is the largest of all the giant isopods. People have claimed to have discovered specimens of this species a large as 30 inches long. That’s certainly bigger than any cockroach you’ll see on land.
You can also find species of the Bathynomus in the Indian and Pacific Oceans. However, those species are generally much smaller. Although some of these giant isopods are pretty big, they really have no ability to harm humans in a physical way. Now, that doesn’t mean that they won’t have any negative effects on your psychological or even financial well-being.
Sea Cockroaches Are Scary
Just because a giant isopod isn’t going to harm you physically, doesn’t necessarily mean that they aren’t still terrifying. After reading up on these strange animals, I’ve discovered that they do have some pretty insidious behaviors.
For one, they’re scavengers, meaning that they feed mostly on dead animals. So, a more apt nickname might be “sea vultures.” These creepy crawlers scramble around the benthic zone (the very bottom of the ocean) and will feed on the carcasses of whales, fish, and squid. And while they do play an important role in the recycling of nutrients back into their environment, eating dead animals is undeniably an offputting trait.
Occasionally, however, giant isopods will also feed on the living. Typically, that includes slow-moving animals such as sea cucumbers, sponges, nematodes, and sometimes even live fish. In fact, giant isopods have become a real problem for commercial fishermen, as they like to attack trawl catches and eat the live fish trapped in the nets.
In fact, on one episode of Alien Sharks: Close Encounters on the Discovery Channel’s Shark Week, they showed a giant isopod eating a dogfish shark alive. The dogfish shark was caught in a trap and the giant isopod killed it by eating its face. If you want to give yourself nightmares, go watch that video.
As you can see, there truly is nothing really cute or endearing about these animals. When they aren’t eating dead stuff, they’re eating off the faces of other creatures. A lot of animals do creepy stuff like that, but the sheer size of giant isopods makes them all the more horrifying.
Why Are They So Big?
What allowed these sea cockroaches to grow so large that they can actually kill sharks? Well, being that they live at the very bottom of the ocean, they tend to have fewer predators because it’s so difficult to live in that part of the ocean.
They also have a strong, calcareous exoskeleton that makes them incredibly difficult to kill. When they get attacked by a predator, they have the ability to roll up into a ball (much like a woodlouse) which protects their more vulnerable undersides and makes them almost impervious to attacks.
Interestingly enough, despite their large size, they don’t have much meat inside of those giant exoskeletons, which makes them rather unattractive to predators. Why would you bother with something so difficult to kill when the reward isn’t even that great? In fact, giant isopods have even less meat than crabs. And if you’ve ever eaten at a crab shack, you know that they don’t have a lot of meat.
Giant isopods are also great survivors, similar to cockroaches. In fact, in captivity, giant isopods have been known to survive up to five years without food. When they do run into a large source of food, however, they’ll gorge themselves to the point where they almost can’t move. Yes, I know that I said at the beginning of this article that you might develop some sympathy for the sea cockroach, but honestly, these things are just gross and creepy. Sorry.