Личинка угря: Лептоцефал и особенности развития

Juvenile eel
the obsolete genus grouping
the cephalic disorder Leptocephaly

A leptocephalus (meaning "slim head") is the flat and transparent larva of the eel, marine eels, and other members of the superorder Elopomorpha. This is one of the most diverse groups of teleosts, containing 801 species in 4 orders, 24 families, and 156 genera. This group is thought to have arisen in the Cretaceous period over 140 million years ago. Fishes with a leptocephalus larval stage include the most familiar eels such as the conger, moray eel, and garden eel as well as members of the family Anguillidae, plus more than 10 other families of lesser known types of marine eels. These are all true eels of the order Anguilliformes. Leptocephali of eight species of eels from the South Atlantic Ocean were described by Meyer Rochow

The fishes of the other four traditional orders of elopomorph fishes that have this type of larvae are more diverse in their body forms and include the tarpon, bonefish, spiny eel, pelican eel and deep sea species like Cyema atrum

The eggs of eels in the order Anguilliformes are quite large compared to those of many other fishes. They are about in diameter. Once the larvae are newly hatched, the yolk extends posteriorly. Some larvae hatch with features of the head more developed than others. The preleptocephalus stage is the period immediately after the larvae hatch. During this stage, the larvae do not yet feed externally. These larvae typically have poorly developed eyes and few or no teeth. Leptocephali are poorly understood, partly because they are very fragile and eat particulate material instead of zooplankton, and their good swimming ability lets them avoid most standard sized plankton nets used by marine biologists. A video recording of a naturally swimming leptocephalus filmed at night off the island of Hawaii shows an example of their swimming behavior.

Two facts are known regarding the visual system of the leptocephali. The first is that they have a rod dominated visual system. The second is that the Synaphobranchidae (a specific family of leptocephali) have telescopic eyes, meaning a tubular eye with a sphere shaped lens on the top occurs. Due to the strange nature of the leptocephali, this has not been easy. Trying to artificially recreate marine snow has proven difficult for scientists. Leptocephali are rarely used as food, except in some parts of Japan. The leptocephali of the common Japanese conger, Conger myriaster, are called noresore·のれそれ in Kōchi Prefecture, Japan, and are often served uncooked to the table, and are eaten after dipping in tosazu mixed vinegar. It is a spring seasonal specialty.