LARVAL DEVELOPMENT OF A SHALLOW-WATER VESTIMENTIFERAN TUBE-WORM, LAMELLIBRACHIA SATSUMA
Miura, T.; Tsukahara, J. & Hashimoto, J
United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890, Japan
Larval development of the vestimentiferan tube-worm, Lamellibrachia satsuma collected from Kagoshima Bay at depths of 80-100 m was studied. The living worms were dissected in a laboratory one to several days after they had been collected. The species is dioecious as are other species of the genus. The vestimentiferan has a pair of dorsal ridges in the male, and grooves with brown-colored fringes in the female. Eggs removed from the anterior part of gonoduct were washed with filtered sea-water. The eggs from more than five females were mixed and then divided into two batches. To one was added just filtered sea-water (without sperm), the other was mixed with sperm-suspended in sea-water. Both of them were subdivided, with female coelomic fluid being added to one. Subsequently, normal development of embryos were observed only in lots without female coelomic fluid. Both groups of eggs with and without sperm developed into larvae. This means that the eggs are fertilized in the gonoduct before their release. Internal fertilization is also suggested by the morphology of spermatophore. The embryos developed into trochophore-like larvae in a day or so. The larval morphology of Lamellibrachia satsuma was compared with other known vestimentiferan tube-worm species and a serpulid worm, Hydroides ezoensis.