Spawning habits and early development of a sargassum fish, Pierophryne histrio(Linne)

Pterophryne histrio (Linne) is one of the sargassum fishes, widely distributed in the warm seas of the world. In 1954, Mosher had observed the spawning behavior of this fish. In the present paper it was reported the results of the repeated observations with some different fact. From July to September, in 1955 and 1956, the senior author observed the spawning behavior and the egg development of this fish at the Mekari Aquarium in Moji City, Fukuoka Pref. and also reared the hatched larvae for 10 days in a glass jar. The eggs were imbedded in gelatinous substance, lying in 2 or 3 layers, each egg separated in a small hexagonal or pentagonal compartment, forming a transparent egg-mass. The eggs rotated freely in these compartments. In the course of development, at 6-11 myotome stages, the firm membranes of the compartment began to decay, and some eggs left the gelatinous substance. The egg is elliptical in shape, measuring 0.53 0.57 x 0.62 0.65 mm in diameter, lacking oil-globule. Half a day or one day before spawning, the abdomen of the female became greatly distended. The courting behavior of the male began in the morning and continued until spawning. The spawning occurred from at 4.00 to 8.00 p. m. in every occasion. At the spawning, the female dashed upward to the water surface, the males following close behind her, resulting in spawning. One of the males dashed into the egg mass and carried it. The authors observed that the male hold an edge of the egg mass in his mouth. The hatching took place in 48 hours and 20 minutes after spawning at the water temperature 26.8-27.4 ℃. In the whole course of development no chromatophore appeared. The n ewly hatched larva, measuring 0.88-1.00 mm in total length, had 18 ～19 (10+8～9) myotomes, lacking melanophore. Minute hexagonal or pentagonal networks, with a small yellowish spot on the corner of the net, were found on the surface of the yolk and larval fin. In four days almost of the yolk was absorbed and the larva attained 1.71～1.73mm in total length. Melanophores were found around the intestine and in the rear side of the eye, but none on the tail nor on the back of the trunk.ハナオコゼPterophryne histrio (Linne) はイザリウオ科Antennariidaeの魚で広く世界の温熱帯の海に分布し,流れ藻に乗つて海面を漂う. ハナオコゼ類の産卵習性については中村秀也が1933年小湊臨海実験所でクロハナオコゼPterophryne ranina (Tilesius) 雌とハナオコゼ雄の間で行われた産卵行動を報告した.その後Gudgerは1937年流れ藻に産みつけられた卵塊がハナオコゼ類の卵ではなくて,トビウオ類の卵であることを明らかにしたが,ハナオコゼの産卵行動及び初期発生については明らかにしていない.1954年Mosherは北米Florida州にあるLernerMarineLaboratoryでハナオコゼHistriohistrio(Linne)の親魚を飼育して産卵に至らしめ,卵の構造,産卵週期,産卵行動,卵内発生,孵化仔魚について詳細に報告しているが,産卵に於ける雄の行動については,同報文中Mosherと一緒に産卵行動を観察して資料を提供したRasquinの観察が一部異なつていることを明らかにしている. 筆者は1955年夏本邦産ハナオコゼの産卵行動と初期発生を観察してMosherの報告とほぼ同様の結果を得たが,一,二の点について異なる観察もあつたのでここに報告する.本研究は主として藤田が行つたもので,内田はその全般的指導に当つた