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 [...]
The excretory organs of Branchiostoma are ectodermal in origin and comparable with the nephridia of annelids and platyhelminthes. The excretory organs of Branchiostoma are different from the kidney of vertebrates. Protonephridia: The protonephridia of Branchiostoma are simple, closed ciliated saclike and thin-walled ectodermal tubules. These are about 90 to 100 pairs arranged segmentally on dorso-lateral pharyngeal wall, one above each [...]