Sea urchin: genomic insights

Article By:

Materna, Stefan C. Department of Biology, California Institute of Technology, Pasadena, California.

Last reviewed:2008

DOI:https://doi.org/10.1036/1097-8542.YB081170

The sea urchin, despite its unusual body plan, is a close relative of the vertebrates. It belongs to the phylum Echinodermata, which also includes sea cucumbers and sea stars. Echinoderms together with their sister group Hemichordata (wormlike creatures) and the Chordata (vertebrates and close relatives) form the deuterostome clade (see Fig. 1). Initially, sea urchins were characterized as deuterostomes based on developmental characteristics, such as gut formation—a classification that is just over 100 years old. [During embryonic development, animals in which the blastopore (the first opening of the early digestive tract) becomes the mouth are called protostomes; those in which the mouth develops after the anus are called deuterostomes.] The sea urchin (see Fig. 2) is the first representative of the echinoderms to have its genome sequenced, which may shine light on what are the common molecular characteristics of deuterostomes. This will further allow conclusions to be drawn about the origin of features that are assumed to be specific to chordates or vertebrates, and will reveal inventions in the echinoderm lineage that indicate the unique characteristics of the sea urchin.

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