Scientists find a new deep-sea eel near Japan

Scientists in Japan have found a new species^*1 of deep-sea eel^*2. Fumihito Tashiro of the Hokkaido University Museum and Munehiro Takami of Tokai University led the study. Both work at universities in Japan. In 2026, they gave the eel the scientific name Ilyophis fukuii.

The eels were caught in Suruga Bay and in other waters in the south of Japan. They live on the sea floor, more than about 1,500 meters down.

The new eel belongs to a family^*3 of eels that live on the deep sea floor. Some eels in this family eat the bodies of large sea animals after they die. Because of this, scientists think these eels are an important part of life in the deep sea.

For a long time, these eels were thought to be one species, Ilyophis brunneus. This species lives in the Pacific Ocean, the Atlantic Ocean and the Indian Ocean. But the two scientists noticed something. Some of the eels had thick tails, and others had thin tails.

At first, they had only a few specimens^*4, because deep-sea fish are hard to catch. So they could not compare the two types well. For more than ten years, they kept collecting eels. They also studied specimens kept in museums and universities in Japan and in other countries. In the end, they had data on more than 80 eels, from young fish to adults.

The two types were different in more than their tails. They had different numbers of bones in their backbones, scales^*5 of different shapes, and lateral lines^*6 of different lengths. The scientists then compared them with the original specimen of Ilyophis brunneus, which is kept in a museum in another country. The thick-tailed eels were the same as this species. The thin-tailed eels were a species that had no name.

The study shows again that some deep-sea fish are not what they seem. A fish that is thought to live all over the world may in fact be several different species that look very much alike.

1. *1 species: one kind of animal or plant
2. *2 eel: a long, thin fish that looks like a snake
3. *3 family: here, a group of animals that are close relatives
4. *4 specimens: animals or plants that scientists keep so they can study them
5. *5 scales: the small, hard, flat pieces that cover a fish's skin
6. *6 lateral lines: lines along the sides of a fish's body that help it feel movement in the water