MOVEMENTS OF THE EPICAUDAL FIN IN COELACANTHS

Citation
K. Hissmann et H. Fricke, MOVEMENTS OF THE EPICAUDAL FIN IN COELACANTHS, Copeia, (3), 1996, pp. 606-615
Citations number
21
Categorie Soggetti
Zoology
Journal title
CopeiaACNP
ISSN journal
00458511
Issue
3
Year of publication
1996
Pages
606 - 615
Database
ISI
SICI code
0045-8511(1996):3<606:MOTEFI>2.0.ZU;2-5
Abstract
Fossil coelacanths, and their only living representative Latimeria cha lumnae, possess a small, supplementary epicaudal fin of unknown functi on at the tip of the large tail. Movements of this fin were analyzed o n film sequences taken with submersibles in the fish's natural habitat off Grande Comore, Indian Ocean. Epicaudal fin beats were not coordin ated with strokes of paired and unpaired lobed fins, and the epicaudal fin did not move continuously. When in action, successive fin beats w ere performed more-or-less rhythmically but varied considerably in dur ation. Epicaudal fin beats occurred mainly in three different situatio ns: during curve swimming, with slow forward motion of the body; durin g narrow turns on a point without significant forward motion of the bo dy; and during station holding without forward, backward, or sideward motion of the body. In the latter case, the fin regularly stood still at maximum deflexion for several seconds. In turns and curves, epicaud al fin beats appeared to have a locomotory function, whereas during ho vering, with standstills of the fin at maximum deflexion, beats presum ably have a sensory function. The lateral-line canal extends to the ve ry tip of the epicaudal lobe. If the lobe is held laterally at an angl e to a local current parallel to the main body axis or to a current re sulting from backward motions, water displacement in front of the lobe could be detected by the lateral line on the lobe.