Is this a cockroach ? No, it is an ISOPOD!

IF you have ever walked through the woodlands or a coastal harbor, you may have likely come across an animal that looks like a cockroach or a beetle. In another situation, if you have bought some fishes, you may have seen an eerie and nasty creature living in their mouths! If you are an avid gamer on Nintendo Switch, you would have seen a bug-like species called “Ligia exotica” that appeared in a fun and exciting video game named “Animal Crossing”. Without venturing too far, you can even find them lurking around your garden too, especially in flowerpots or terrariums. So, what are these so-called bugs that look like cockroaches or lice, but aren’t bugs at all?

A variety of isopods and their different of diet, terrestrial isopod (left) and parasite isopod (right)

These creatures are known as “ISOPODS”, where “iso” means “equal” and “pod” stands for “foot”. The common name for the isopods is pill bug, woodlice, roly-poly, sea wharf, sea roach, or sea slater. Isopod is a diverse crustacean group which is similar to the shrimps, crabs, prawns, and barnacles. The order Isopoda has a worldwide distribution of 10,000 known species, where 5,000 species occur on land, 4,500 species are found in marine environments (mostly on the seabed) and 500 species occur in freshwater ecosystem (Source: The Biology, Ecology, and Societal Importance of Marine Isopods). Due to the high diversity of isopod species, they are able to inhabit terrestrial ground, deep-sea sediments, rocky and sandy beaches, and in hosts like fishes and crabs (acting as parasites).

Isopods have a variety of morphological features that are functional for their adaptation. Because of this, they can come in a variety of colors, shapes, and sizes. For terrestrial isopods, they have colorful pigmentations and patterns on their bodies, making them beautiful and attractive pets for care and breeding. From their colors, they are given common names such as zebra line, rubber ducky, blonde ducky, and the dark knight.

An appendage of isopod parasite like a hook called dactyli

Isopod display in a variety of feeding modes. They can be scavengers, detritus feeders, predators, parasites, and filter feeders. For example, isopod parasites from the Family Cymothoidae use their dactyli to hook onto their host’s flesh. Cymothoid isopods are striking ectoparasites on fishes that include the famous “tongue biters”. Cymothoids have four feeding attachment modes: mouth-attaching, gill-attaching, skin-attaching, and flesh-burrowing species. Sometimes, a single cymothoid species can parasitize multiple host species.

Here’s a fun fact: this unique isopod can be eaten! Certain families within the isopod group can be eaten like other crustaceans. Although Malaysians have not explored this delicacy yet, Japan and Vietnam have incorporated the giant isopod called deep-sea gigantism in their favourite dish and have acknowledged it to taste just like chicken! According to The Japan Times, they also make food products such as crackers made from giant isopods! If you would like to see a giant isopod in Malaysia, you can go to Aquaria KLCC to observe how big it is!

A giant isopod and its baby (arrow) on the telson

Isopods play an important role in aspect of ecology and economy. For instance, a research study used a combination of an ointment with the extraction of an isopod parasite from a species Ceratothoa oestroides to heal diabetic foot ulceration. In traditional Chinese medicine, another species of semi-terrestrial isopod, Ligia exotica is used for the treatment of muscle injury, swelling, and pain, or to heal malnutrition in children. In ecology, terrestrial isopods are used as an indicator to monitor the study of soil toxicity as they are decomposers and grazers in nutrient and organic soil. In another report, a species from the Family Cirolanidae is used to clean the skeletons of marine organisms such as the marine mammals for museum collections. In the next time, you can go to the market and check the fish of their tongue or gills and look for the isopod!

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