Physiological and ecological
study of pogonophora
inhabiting the Tsukumo Bay of the
Japan Sea
Yuichi
Sasayama, D. Sc., Professor |
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Beard worms (pogonophora) inhabit the sea bottom of various seas of the world including the Japan Sea. Sincethese worms have no mouth, digestive tract and anus, it hasbeen an enigma how they live. Recently, it became clearthat they live by keeping symbiotic bacteria (chemotrophic bacteria) , which produce carbohydrates without solarenergy. In other words, beard worm give the bacteriasome substances that are necessary for them and getsome carbohydrates from them. Since the habitat of thisworm is limited to cold seas and abyssal seas, researchon the physiology and ecology of pogonophora hasadvanced very slowly. Furthermore, most specimens of various species in pogonophora lack the body end (opisthosoma) because their body is too slender.
On the other hand, in the Tsukumo Bay of the NotoPeninsula which projects to the Japan Sea, one species of pogonophora, Oligobrachia mashikoi, was found in 1973. This species lacked the opisthosoma, as other species.Recently, however, we succeeded in collecting thewhole length of the body including the opisthosoma by devising a dredger. This is the first record in this genus.However, the opisthosoma was quite different in morphology from that known so far, which suggests that this is an interesting species from the viewpoint of evolution of pogonophora. Furthermore, we succeeded in taking actual pictures of this species, which lives at adepth of 25m from the sea surface, by placing a video camera there. This is the first visual record in the world of any pogonohora species.
At present, using modern techniques of biology, we are clarifying the
details of how this worm lives. Our study will proceed in an attempt to
understand why all forms of life on earth must have different lifestyle.
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