Press Releases

June 11, 2007
The Japan Agency for Marine-Earth Science and Technology

Discovery of a Unique Life Form on Deep Sea Floor
Possibility of a New Ctenophore Species

The Agency for Marine-Earth Science and Technology (JAMSTEC: Mr. Yasuhiro Kato, President) have observed a comb jelly (Ctenophore*1) of unique morphology. Analysis of images obtained in Ryukyu Trench, which is approximately 200km south off of Okinawa main island, showed it is highly possible to be a newly-discovered species and different from any currently known ctenophore.

The images were captured during the training dive of the ROV KAIKO on the sea floor at a depth of 7,217m in the Ryukyu Trench (2425N, 12775E : Appendix) on April 5, 2002. In addition to the images, reviewing and reorganizing of the taxonomy of cydippid ctenophores led to this discovery.

This result will be published in the International scientific journal, "Plankton and Benthos Research", volume 2, Number 2.


This marine benthos is a kind of ctenophore with two long filaments (thread-like structure) anchored to the sea bottom and floating like a kite, extending two tentacles from the opposite end of the body to prey on animals. (Pic.A~D)

Precise analysis of the images clarified that the marine benthos observed this time belongs to phylum Ctenophora, since it possesses eight comb rows. And since it has two tentacles and doesn't have sleeve-like or auricular processes, it appeared to belong to a family of cydippid ctenophores. However, it is likely to be a new species, for commonly known cydippid ctenophores have never been observed with filaments or to be attached to the sea floor with them.

Observed animals were not collected and the images obtained did not offer enough information to analyze the internal structures. In order to describe the species and include it in the current taxonomy, collecting samples are required because specific study of inner structures such as water-vascular system is necessary.


*1 Ctenophore (comb jelly):
Ctenophore belongs to phylum Ctenophora and has structure called comb rows. Beroida, Lobata and Cydippida are typical and seen around the coast often. It is different from so called jelly-fish, even though it is called comb jelly, as jelly-fish (Aurelia, Stomolophus nomurai, etc.) belong to Cnidaria and possess nematocystic tissue. Both called jelly-fish because both bodies are transparent and gelatin like. But they are taxonomically different at phylum level. Currently, 100~150 species of existing ctenophore are known in the world.


(For This Research)
Research Scientist Dhugal Lindsay, e-mail:
Invited Research Scientist Hiroshi Miyake,
Marine Biology and Ecology Research Program,
Extremobiosphere Research Center(XBR)
Mr. Noriyuki Murata, email;
Manager, Research Promotion Office, XBR
(For Publication)
Mr. Shinji Oshima, e-mail:
Manager, Planning Department Press Office