Thursday, May 20, 2010

Juvenile brittle star in polarized light

I dissected this juvenile brittle star (Class Ophiuroidea) from a brood pouch of the adult, Amphipholis squamata. Through careful removal of the legs and the mouth plate, I was able to extract the brood pouch (also called genital bursa) containing the juvenile brittle star pictured here. This species is placental and broods its young instead of releasing gametes into the water column. This specimen is approximately 3 millimeters in diameter and is photographed under a system of polarizers. These cause the calcareous spicules present in the juvenile to glow on a dark background. See another blog post by Kristina Sawyer which pictures a similar specimen under regular transmitted light. The intricate skeleton of the juvenile forms the basis for the skeleton of the adult brittle star.

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