Saturday, August 7, 2010

August 7, 2010 : Pearlfish


Pearlfish is a general name for a variety of marine fish species in the Carapidae family. Pearlfish have been found in tropical waters of the Atlantic, Indian, and Pacific Oceans at depths up to 2,000 metres (6,600 ft) along oceanic shelves and slopes.

Pearlfish are slender fish, distinguished by having dorsal fin rays that are shorter than their anal fin rays. They have translucent, scaleless bodies reminiscent of eels. The largest pearlfish are about 50 centimetres (20 in) in length. They reproduce by laying oval-shaped eggs, about 1 millimeter in length.

Pearlfish are unusual in that the adults of most species live inside various types of invertebrate. Typically, they live inside clams, starfish or sea squirts, and are simply commensal, not harming their hosts. However, some species are known to be parasitic on sea cucumbers, eating their gonads. Regardless of the habits of the adults, the larvae of pearlfish are free-living among the plankton. Pearlfish larvae can be distinguished by the presence of a long filament in front of their dorsal fin, sometimes with various appendages attached.

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