Analyzing DNA, scientists discovered a new giant sea lice species

Specimens of Bathonymus yucatanensis at Japan's Enoshima Aquarium.

As published in the Journal of Natural History on August 9, international researchers from Taiwan, Japan and Australia named the new species Bathonymus yucatanensis. It is about 26 cm long and 13 cm wide, up to 2,500% larger than the common wood louse.

There are about 20 known species of giant sea lice in the genus Bathonymus, 14 of which inhabit the deepest, darkest and coldest waters of the Atlantic, Pacific and Indian oceans. The largest genus of crustaceans in this order are also known as "living fossils" when they roamed the ocean floor from the Middle Age tens of millions of years ago, according to BBC.

The specimen Bathonymus yucatanensis in this study was collected from a trap off the Yucatán peninsula of Mexico in 2017 at a depth of about 600 to 800 m, and subsequently acquired by the Enoshima Aquarium in Fujisawa, Japan.

For the past five years, it was confused with another giant sea lice, Bathonymus giganteus, until biologist Huang Ming-Chih from Taiwan's National Tainan University decided to sequence its DNA. animals in a research project on arthropod genetics.

The genus Bathonymus are known as living fossils.

Huang was surprised to see a significant difference between the genomes of the new sea lice and Bathonymus giganteus. "At first, I thought there was a mistake, so I repeated the DNA sequencing experiment a few times, but the results were still the same," said the lead author of the study.

Compared with Bathonymus giganteus, Bathonymus yucatanensis has a slimmer body proportions and a shorter total length. Its extremely long beard and milky yellow body also stand out more than its gray relative.

Despite its intimidating appearance from prehistoric times, Bathonymus yucatanensis is harmless to humans. They mainly feed on the carcasses of fish and whales sunk on the ocean floor.