If you go down to the intertidal shrimp pond today, you’re sure of a big surprise – which is certainly what researchers in Hong Kong received when they discovered a completely unknown species of box jellyfish, the first species of box jelly ever to be found in Chinese waters.
The class Cubozoa, most commonly known as box jellyfish, has around 50 known species including the world’s most venomous jellyfish, the Australian box jellyfish. This class is subsequently split into two easy-to-tell-apart orders: the carybdeids which have only one tentacle per pedalium (the pad at the bottom of the bell), and the chirodropids which have several tentacles per pedalium.
This new species is a member of the carybdeids, more specifically a family known as Tripedaliidae, which previously consisted of just three other species. During the summers of 2020, 2021 and 2022, researchers noticed these unusual translucent cube shaped jellyfish in samples collected from an intertidal shrimp pond in a mangrove habitat (locally known as gei wai) in Mai Po Nature Reserve, Hong Kong. This new species adds a fourth member to the already described species of Tripedaliidae.
“Box jellyfish are a small group of cnidarians with only 49 species reported worldwide. They are poorly known in Chinese marine waters. Our discovery of 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 Professor Qiu Jianwen, a Professor of the Department of Biology at HKBU and study author in a statement.
The new species has been named Tripedalia maipoensis in honor of the reserve where it was collected. This new tiny jelly has a transparent, colourless body with an an average length of 1.5 centimeteres (0.5 inches). At each corner of the body there are three tentacles that are around 10 centimeters (3.9 inches) long. These tentacles end in small paddle-like structures that help the jellyfish speed through the tidal estuary where they were found, much faster than other species.
The team also found that the new jelly has 24 eyes, arranged in four groups of six, around its bell. On each side, the jelly has two larger eyes known as the upper and lower lens eyes, which are next to the four smaller eyes known as the pit eyes and the slit eyes. Only two of these eyes can see images, while the other four are used to detect light. It is not yet known if the jellyfish is venomous since the researchers have understandably refrained from touching the specimens.
The team suggests that future studies should look more at Chinese coastal areas to improve the understanding of the distribution and ecology of this new species.
The paper is published in Zoological Studies.