New jellyfish stings researchers to think out of box

A Baptist University-led team has discovered a new species of potentially dangerous box jellyfish in the Mai Po Nature Reserve in the SAR.

The new species Tripedalia maipoensis, which has a cube-shaped body and 24 eyes, was named to reflect its type locality.

It is the first discovery of a new species of box jellyfish in China, making it the fourth species of the Tripedaliidae family.

The new species was accidentally found in May 2020 by the World Wide Fund for Nature Hong Kong.

That saw wetland research manager Carmon Or Ka-man and colleagues come across a large gathering of 300 to 400 jellyfish when walking past a brackish shrimp pond - locally also known as gei wai - after lunch.

They collected the jellyfish samples initially to identify the species and learn about their living habits, but found the samples couldn't match any existing species in the gene pool.

The fund then collaborated with the research team to analyze their characteristics and to carry out gene sequencing, and finally confirmed it to be a new species.

Or said it was surprising to find the box jellyfish here.

The jellyfish has a transparent and colorless body with an average length of 1.5 centimeters. There are three tentacles that are up to 10 cm long at each of its four corners.

Pedalia, a flat pedal-shaped structure at the base of each tentacle that looks like a boat paddle, allows the jellyfish to produce strong thrusts when they contract their bodies, enabling them to swim faster than other kinds of jellyfish.

There are six eyes on each side of the box jellyfish's body, two with lenses that enable image-forming, while the other four can only sense light.

Associate animal specialist Ringo Cheung Nga-zing at Ocean Park said the jellyfish needs a lower water salinity of 17 parts per thousand compared to 33 ppt for other jellyfish, and a higher water temperature of 26 to 27 degrees Celsius.

The box jellyfish also has been reared in Ocean Park since May 2021 and is expected to be on display soon.

"Our discovery of the Tripedalia maipoensis in Mai Po - a relatively well-studied area in Hong Kong - highlights the rich diversity of marine life in Hong Kong and even the whole of China," said research team leader Qiu Jianwen, a biology professor at the university.

As the gei wais are connected to the estuary through a tidal channel, Qiu believed this species can also be found in the adjacent waters of the Pearl River estuary.

Qiu said box jellyfish, widely found in tropical waters, are extremely toxic, with Australia even posting warning signs on its beaches.

"According to records, an estimated 64 people died from box jellyfish stings between 1884 and 2021," he said, warning against handling them..