The Second Example of Metamorphosis of the Medusa from the intermedia Form to the Southern Form in Eutima japonica (Leptomedusae, Eirenidae)

One typical, mature medusa of the intermedia form of Eutimajaponica from Zagashima Island, Mie Prefecture, developed into the mature medusa of the southern form of this species in the laboratory, as had been observed once before by the author in another population from Tsushima Island, Nagasaki Prefecture. The morphology of this female specimen is described. This second example supports the recently proposed demotion of Eucheilota intermedia to the intermedia form of Eucima japonica

Basal-disc creeping combined with rotation, an undescribed behaviour with preferred directionality in bivalve-inhabiting hydrozoans (Cnidaria: Hydrozoa: Leptomedusae)

A creeping movement, which often results in clockwise or counterclockwise bodily rotation, is described for ordinary zooids of two species of bivalve-inhabiting hydrozoans, Eutima japonica Uchida and Eugymnanthea japonica Kubota, attached to artificial hard substrata (polystyrene and glass) in the laboratory. Time-lapse video recordings furthermore showed that the non-transparent half of the flat, ellipsoidal pedal disc always faces forward during this motion, with no lateral or backward creeping during either day or night. Because an ordinary zooid generally crept in a circle of small radius, the zooid's body rotated as the creeping proceeded. One full rotation of a zooid of either species took about 5–6 hours on average at 21–25°C. The direction of rotation of an individual zooid was nearly constant irrespective of developmental state, this being true for zooids with or without a medusa bud on the hydrocaulus or a daughter zooid on the pedal disc, those with a normal or a double hydranth, or those consisting of a bare hydrocaulus. Asexually produced tiny daughter zooids quickly became well separated from their mother zooids. The attachment site of the latter did not shift much as they rotated, but daughter zooids and other tiny free zooids creep along a nearly straight line, thereby markedly shifting their position. This may contribute to the prevention of crowding of zooids in the restricted space between soft body parts in the host bivalve's mantle cavity

Two Species of Koellikerina Medusae (Cnidaria, Hydrozoa, Anthomedusae) from Japan

We fully described two Koellikerina species from shallow waters in Japan with illustrations and photographs. Koellikerina constricta (Menon, 1932), bearing characteristic bell constriction, expands its distribution to Kuchinoerabu Island, Kagoshima Prefecture (northern limit). Koellikerina bouilloni n. sp. is added to eight known species of the genus Koellikerina on the basis of an absence of bell constriction, a colorless body, and the presence of adaxial ocelli, perradial gonads, and a peduncle by examining a specimen from Tanabe Bay, Wakayama Prefecture and 18 specimens formerly collected from Papua New Guinea. Although bell constriction has been criticized as a taxonomic character, we conclude that it is reliable among Koellikerina because all the K. bouilloni specimens at variable developmental stages lack bell constriction and are clearly distinguishable from K. constricta

Description of Some Oceanic Hydromedusae from Japan

Based on zooplankton collections made by Fisheries Three species of oceanic hydromedusae, Sminthea eurygaster, Crossota alba, and Cytaeis tetrastyla, are described and illustrated based on the specimens collected in the Pacific Ocean, off central Honshu, Japan. Sminthea eurygaster is the first record in Japan. One out of the three specimens of Cytaeis tetrastyla bears both the polypoid and the medusa buds. This is the second record of such an asexual reproduction of the species and the first record in the Pacific Ocean

Planuloid budding from a cutting plane of polyp stalk of Cassiopea sp.(Cnidaria, Scyphozoa)

Cassiopea polyps that appeared in culture vessels of Turritopsis sp. polyps at the Seto Marine Biological Laboratory, Kyoto University in 2014 were experimentally amputated their stalks from the calyxes. On the cutting plane, planuloid buds were exclusively produced and stalks were never regenerated. Planuloids became polyps but some of them were never produced stalks. It is assumed that the polyp that accidentally lost its stalk has a chance to raise their survival rate by releasing multiple of planuloids

Histological Studies on Some Organs of Two Male Dealfishes, Trachipterus ishikawae, Caught on the Beach of Shirahama, Wakayama Prefecture, Pacific Coast of Japan

The testis, thyroid, kidney, exocrine pancreas, endocrine pancreas (=Brockmann body), spleen and liver of two dealfishes, Trachipterus ishikawae, collected on the beach of Shirahama, Wakayama Prefecture, Pacific coast of Honshu, Japan, were examined histologically. The specimens measured 2.30 m (specimen A) and 1.65 m (specimen B) in total length. The testicular lobes were atrophied and sclerotized, having the appearance of an aggregation of numerous protuberances (or spherules), each spherule corresponding to a lobule containing a number of cysts, although some of the latter had collapsed and/or merged with each other. Each cyst contained sperms and spermatids, relict sperms being found in the spermiduct. The thyroid gland, an amorphously soft body, located dorsally on the ventral aorta and its afferent branchial arteries, was composed of many variously-sized follicles. Each follicle comprised a large amount of smooth colloid, surrounded by a flat epithelium consisting of cubic cells. The overall condition indicated an inactive state. In the kidney, a great deal of stromatous tissue, including AF positive lipid grains, and a small number of glomeruli were apparent. In both specimens, the thread-like loose connective tissue comprising the exocrine pancreas attached to and running parallel with the liver, stomach, Brockmann body and spleen, were composed of acini with zymogen-rich pyramidal cells. Details of cell types in the Brockmann body were difficult to determine. Fatty deposits were absent from the liver of specimen A, which was characterized by rich stromatous tissue and dilated sinusoids. However, rich fatty deposits were found in several portions of the liver of specimen B. Well-developed stromatous tissue and nodules of red- and white pulps were recognized. It was concluded that the two specimens were spent and debilitated males