Morphological development of halibut (Hippoglossus hippoglossus) larvae with special reference to mouth development and metamorphosis

Abstract

Halibut (Hippoglossus hippoglossus) larvae were raised from hatching\nto beyond metamorphosis in 11.5 m3\nplastic bags with a temperature stable around 6°C. Standard length, myotome height, eye diameter and\nyolk sac length were measured on live or freshly preserved material.\nMouth development and functionality, pectoral and pelvic fin\ndevelopment, intestinal development and the initiation of peristaltic\ncontractions, and eye pigmentation and migration were observed from\nlive material. The gape of the jaws was limited by an oral membrane\nwhich appeared coincident with the developing mouth and which\npersisted in either full or remnant form up to around the time of\nfirst feeding. The phenomena of yolk sac vesicles and the Non-reducing\nYolk Sac Syndrome are discussed.