Aquarium Jellyfish Turns Out to Be Undescribed Species
Aquarium Jellyfish Turns Out to Be Undescribed Species

Aquarium Jellyfish Turns Out to Be Undescribed Species

The newly characterized “elegant jellyfish,” roughly the size of a human hand, had been on display in two aquariums in Japan for more than a decade.

Lisa Winter
Jun 18, 2021


The world now has one more species of named jellyfish and it’s been hiding right under scientists’ noses for more than a decade. Tima nigroannulata, the species formally described in a June 8 paper in Zoological Science, was mistaken for a closely related cousin until genetic analyses revealed otherwise.  

When the animals, nicknamed elegant jellyfish, were initially collected off the coast of Japan, they were assumed to be T. formosa, a species that lives in northern Atlantic waters. Researchers had even kept the animals alive and reproducing for more than 15 years at two public aquariums in Japan with the label T. formosa. Their uniqueness was only revealed when DNA sequencing of the animals’ tissues, completed at Hawai‘i Pacific University, did not match any known species.

A fully grown adult is about the size of a human palm, with an umbrella (also called a bell) that is between 23 and 46 millimeters in diameter and 12 to 38 mm tall. The bases of T. nigroannulata’s 53 tentacles fluoresce under a blacklight, but it is not yet known if it has the same bioluminescent capabilities as some others in the genus. So far, they’ve only been found in temperate waters (roughly 20 °C).

Each elegant jellyfish has granules of pigment around the base of its umbrella, creating a black ring of spots, and in some cases, those freckles extend to the top of its tentacles. In fact, the species name nigroannulata is derived from the Latin words for black and ring: niger and annulus, respectively.

Tima nigroannulata swimming in Japan’s Kamo Aquarium, where it had originally been labeled as one of its close cousins
Kamo Aquarium, Japan (Shuhei Ikeda)