Pegasidae

Article By:

Bailey, Reeve M. Division of Fishes, Museum of Zoology, University of Michigan, Ann Arbor, Michigan.

Last reviewed:August 2019

DOI:https://doi.org/10.1036/1097-8542.494700

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• Pegasidae, published June 2014:Download PDF Get Adobe Acrobat Reader

A small family, also known as the Hypostomides, of peculiar actinopterygian fishes, consisting of the sea moths or sea dragons. The family Pegasidae belongs to the order Gasterosteiformes [class Actinopterygii (ray-finned fishes)]. The precise relationships of its members are unknown. The body of individuals is encased in a broad, bony framework anteriorly and has bony rings posteriorly (see illustration), simulating the seahorses and pipefishes. Unlike those fishes, which have the mouth at the tip of the produced snout, sea moths have enlarged nasal bones that form a rostrum that projects well forward of the small, toothless mouth. The preopercle, pterosphenoid, intercalar, entopterygoid, and metapterygoid bones are absent, and the gill cover has a single bone. The greatly expanded and winglike horizontal pectoral fins belie its appearance and do not function in aerial gliding. The pelvic fin is abdominal and consists of a slender spine and one or two long rays. The short, opposed dorsal and anal fins have no spines. There is no swim bladder. See also: Actinopterygii; Gasterosteiformes; Swim bladder

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