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An off-the-wall question:

Does anyone have any good hypotheses about the function of the elongated
dorsal filaments that are found in some fish species?

In the lower teleosts:
Tarpon have very long filaments, ladyfish don't.
Shafted bonefish (Albula nemoptera) has the dorsal filament, bonefish (A.
vulpes) don't.
Three or four North American clupeids have filaments, the rest don't.

In the elasmobranchs, many species have some sort of elongation of the
dorsal fin beyond the fin base, but the fin seems elongated into distinct
filaments in hammerhead, bonnetheads and others.

A hydrodynamic function?  Maybe in elasmos, who have larger, stiffer
filaments, but in the slender , flexible filaments of teleosts?
Why would some closely-related species have them, and others not?

Would removing a portion of the dorsal filament of a tarpon (for DNA
analysis) have an impact on the fish?

Any information or speculation would be welcome.

On another note:  My old copy of Reuben Lasker's (ed.) Marine Fish Larvae
has finally been shredded beyond repair before I found time to photocopy it.
It's an oldie but a goodie for helping students get started in the larval
fish field.  I haven't had any luck finding a copy for sale in the used book
web sites.  If anyone sees a copy for sale, please let me know.

Thanks.

Jon Shenker, Ph.D.
Associate Professor of Marine Biology and Aquaculture
Department of Biological Sciences
Florida Institute of Technology
150 West University Boulevard
Melbourne, FL 32901
321-674-8145
FAX 321-674-7238
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