Blue Sea Star - Porpita porpita

© 2000 by Image Quest 3-D
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This floating hydroid colony, commonly referred to as the blue sea star or the blue button, belongs to the phylum Cnidaria, class Hydrozoa, family Velellidae. It is covered by a chitinous float and surrounded by a membrane that lies on the water surface film. The float is usually a golden brown and the mantle and hydroid colonies beneath it vary from a deep turquoise blue to lemon coloured. The surface drifting hydroid stage is the most well known - the 0.3 - 2.5 mm tall medusae that are liberated from this hydroid stage are rarely seen in the field.

This colony is viewed from beneath with the clouds and sky up above - idyllic, but deadly to the other microplankton that live in this two-dimensional ecosystem and that are careless enough to brush against those delicate tentacles.

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2001 by Image Quest 3-D
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