The phylum Echinodermata contains five classes of marine life:Asteroidea(sea stars),Ophiuroidea(brittle stars and basket stars), Echinoidea (sea urchins and sand dollars), Holothuroidea (sea cucumbers), and Crinoidea (sea lilies and feather stars). They are a diverse group of organisms, containing...
A blastula stage nucleus from the sand dollar Echinarachnius parma was injected into an activated but nonnucleate egg fragment of the ascidian Ciona intestinalis. During culture, some of the "hybrid" embryos displayed ultrastructural evidence of cellular differentiation. Two recognizable features were (...