Bloodsucking, Parasitic Creature That Looks Just Like Salmon Sushi Discovered in Japan

A strange-yet-adorable creature was discovered in Japan, and it has caught the attention of locals for its uncanny resemblance to a piece of salmon sushi.

Identified as belonging to the genus Rocinela, these types of creatures, frequently referred to as isopods, are related to commonly-known crustaceans like shrimp, crabs, and lobsters. Isopods, however, are "the most morphologically diverse of all the crustacean groups," explained the National Oceanic and Atmospheric Administration (NOAA).

There are estimated to be 10,000 different types of isopods, ranging in size from "micrometers to a half meter in length." About half of isopod species live in the ocean, explained the NOAA, and many, especially small ones, are parasitic—meaning that they live and feed off of a host creature.

This particular isopod, discovered near Rausu, a town on Japan's northern island of Hokkaido, is unique among its peers, reported Vice. Isopods are typically brown in color, whereas this inch-long specimen is an eye-catching shade of orange-pink.

Combined with the white stripes—resembling streaks of fat—along its back and its white belly, the creature looks almost indistinguishable from a piece of salmon nigiri. Only upon closer inspection are the isopod's thin legs and black eyes visible.

The salmon-esque parasite was first caught by fishermen, noted Vice. In July, it was brought to the aquarium Aquamarine Fukushima for display. It remained unknown, however, what animal the isopod had been feeding off of before its capture.

At the time, the aquarium posted a photo of the acquisition on Twitter, comparing it side-by-side with a traditionally-colored isopod—and the difference between the two is striking. The post, which can be viewed here, has since gone viral, amassing nearly 29,000 likes and over 13,000 retweets.

Aquarium officials have a theory as to why the creature may have developed such amazing coloring. "Because they're parasitic, we think maybe the color of the fish it was feeding on transferred," said caretaker Mai Hibino to Vice.

She added that its belly appeared full when it arrived to them, meaning that it was likely well-fed. "Its belly is still swollen, which means it's probably full from when it was still a parasite and feeding on another animal," she told Vice. "When its belly gets flatter, that means it's hungry."

Aside from a brief stint in July, for the majority of the time that the isopod has been in the aquarium's care, their facilities have been closed to visitors due to COVID-19 lockdown restrictions. On Friday, they opened for the first time in about two months—and people were thrilled to see the unbelievably cute parasite in action.

Said Hibino: "We didn't know how long we'd be able to put the animal on display, or if it'd even live. But it held out—it stayed alive for us."

Salmon Sushi
Salmon sushi served in California, 2019. A parasite, bearing an uncanny resemblance to salmon sushi, was discovered recently in Japan. Smith Collection/Gado/Getty Images