The peculiarities of larval development of the European smelt Osmerus eperlanus eperlanus (L.)

The larval development of the European smelt Osmerus eperlanus eperlanus from hatching to full resorption of the vitelline sac has been described. On the basis of the morphological and dimensioning characteristics, three stages almost equal in the duration have been distinguished during present period. The duration of the larval stages was measured in relative units τ_s. Two palingeneses were discovered during larval development of the smelt: (1) the presence of the ciliary epithelium in the intestine and (2) plasmatic circulation of the blood without blood cell formation. These features are evidence of the antiquity of the origin of smelt and place them at the base of the suborder Salmonoidei.