Development of Branchiostoma (Amphioxus) is indirect involving a larval stage. Early embryology of Branchiostoma is simple. Therefore, the transformation of egg, which having less yolk, into a complex and differentiated animal is far easier to follow than in any other vertebrate. The early development of Branchiostoma (Amphioxus) is of great phylogenetic significance because it resembles with those of invertebrates like [...]
In this article we will discuss about the external morphology of branchiostoma with the help of suitable diagrams. Shape, Size and Colour: Branchiostoma is about 3.5 to 6.0 cm in length. The body is slender, somewhat translucent, superficially fish-like, laterally compressed and pointed at both ends, hence, the name lancelet. The anterior two-thirds of the body is roughly triangular in [...]
Sexes are separate but males and females are alike showing no sexual dimorphism. Gonads: The gonads, either testes or ovaries, lie in the ventro-lateral part of the body wall beneath the myotome, projecting into the atrium. There are about 26 pairs of testes or ovaries arranged metamerically, i.e., one pair in each of the segments 25 to 51. They [...]