SERCH FOR LIVING FOSSIL IN TWILIGHT ZONE -Coelacanth filming by latest high deep diving technique and by hypersensitive camera-

Some notes on Coelacanth

So called living fossil “Coelacanth, Latimeria chalmunae” discovered 1938 and described by JLB Smith. The out looking is almost identical with the ancestral form of some three hundred million years before. Because of lacking record of fossil for the recent sixty five million years, Coelacanth was regarded as an extinct group to be extinct up to that time. The discovery of the extant individual was, then shocked much not only scientists but usual citizens at that time. Moreover the second species of the same group, Latimeria menadoensis was found and reported from Indonesia in 1997. The recent discovery of the species in nature by Peter Timm by underwater diving in 2000 at Sodwana Bay, South Africa shocked people again. Search for the living individual for these species by ROV (remote operating vehicle) has been eagerly tried and at present, their appearance is recognized from Tanzania, Comoro Islands, and South Africa for L. chalmunae and from Sulawesi and Papua New Guinea for L. menadoensis. More than 300 individuals have been caught accidentally up to now by fishermen. The living Coelacanth is regarded as an important symbol of the planet Earth environment, and have been received interest of citizens of all generations. The oldest Coelacanth fossil was recorded from late Devonian, 365 million years ago. They thrived early Triassic (248-242 million years ago) at shallow sea and some groups entered even to freshwater zone. Most species had been extinct up to Late Cretaceous (100my). And the recent Cenozoic formation (65million years ago up to present) lacks fossil of the Coelacanth. This lack of the fossil record resulted belief of the extinction of the group up to the Smith’s report of 1938.

The reason why they survived?

Fossil Coelacanth are known from about 80 species, but the extant species includes two species, viz Latimeria chalmunae and L. menadoensis. They hide themselves in the sheltered lava-caves. Their preference water temperature ranges from 14-21°C at Indonesian waters, 16.5-22.8°C at Comoros, and below 16-19°C at South African waters. They seem to have chosen this rather peaceful habitat with less competition without other voracious predators in competition. This relatively stable environment of twilight zone, like other living fossils of deep sea, made it possible to survive that Latimeria could to survive through its long geological history with less change in morphology. Focussing on observation for this species, we can expect various features of the living fossils for their conservation.

Habitat of Coelacanth

Observation by submarine for Comoro’s population, they rest lava-caves in small numbers at daytime and at night, they drift singly for search for prey at steep lava-slope. They appear layers between ca100 to 250m. While at Indonesian water, they rest caves at layers of 150m or more. The population of South Africa, they are observed at shallower caves of layers between 91 to 120m deep.

Why Coelacanth?

Because of their deeper water appearance, we cannot observe Coelacanth with use of usual SCUBA. From early 1980’s, IANTD started it’s activity for deep water diving as a branch of NOAA and started training deep diving with rebreather charged with mixed gasses. Nowadays it became possible to dive at 150m deep and return surface without any trouble. Because of highly sophisticated tool than usual SCUBA diving, this method requires much knowledge and high technique for the divers of themselves. The severe training is comparable with extravehicular activity of astronauts. This high tech made it possible to encounter with Coelacanth. Because of their exploring spirit brought the real encounter and direct observation on the living fossil. Knowing mysterious coelacanth as the ancestor of the tetrapods, we do believe to get clues for future of all living creatures. We stand up to tell the sea, magnificent but with fragility together with living creatures of it, not only for next generation but for citizens lost their dreams. We will be happy to re-evoke the importance of challenging spirit, accomplishment, and to have a dream.

Filming using the latest technology

Using the newest model of “VR camera” and “4K video recorder”, we will monitor coelacanth as long as possible and challenge to record throughout the day, especially at night time which has yet to be clarified. Adding to these, their environmental factors such as water temperature, current velocity and its direction and the fish fauna as food resources or as competitors will be monitored. Using by our technique and educational system of IANTD Japan, we would like to clarify the difficulty and the possibility with safe diving up to the depths of the habitat of Coelacanth. The objective of this point covers clarification of the difference between diving by helium mixed gas and usual air diving. We do hope to evoke passion and interest of the world citizen on coelacanth of course, ocean, and technique for diving through the visualization of the latest technique and educational process of rebreather.