Order Summary for Pleuronectiformes
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Main Ref |
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Order |
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Pleuronectiformes flatfishes |
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Class |
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Actinopterygii |
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Sister Order |
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Tetraodontiformes 15 M years |
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Ref.. |
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First Fossil Record |
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late Tertiary |
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Occurs in |
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Marine |
Fresh |
Brackish |
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Remark |
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Adults not bilaterally symmetrical, with one eye migrating to the other side of the cranium; dorsal and anal fins with long bases, dorsal fin base overlapping at least the neurocranium except in Psettodes; body highly compressed, somewhat rounded on eyed side and flat on blind side; eyes can protrude above body surface allowing fish to see when buried in the substrate; usually six or seven branchiostegal rays, rarely eight; body cavity small; adults almost always without swim bladder; scales cycloid, ctenoid, or tuberculate.
About four species probably occur in freshwater, while another 20 species that are normally marine occasionally enter freshwater. |
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Classetymology |
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Greek aktis = ray, thunderbolt, beam + Greek pterygion, diminutive of pteryx = wing, fin. Ref. 45335. |
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Orderetymology |
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Greek, pleura = similar, ribe, side + Greek, nektos = to swim + Latin, forma = shape. 1849 (Ref. 45335). |
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Families |
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Converted to PHP by Kit 06.10.09 |