Gill raker morphology in some Red Sea fishes of different feeding preferences

الملخص EN

Samples of twenty-six different Red Sea fish species have been collected from areas near Jeddah.

For studying the gross morphology of the gill rakers bucco-pharyngeal cavity have been dissected.

Also, entire gut-contents; especially that of the stomach, have been examined to determine the nature of food.

This is an attempt to correlate between shape and nature of the gill raker with the nature of food.

It is noticed that, carnivorous fishes are characterized with their few and limited numbers of rakers which slightly varies among the same species.

Rakers of the outer most row are well-developed and longer than that on the following row.

All rakers are provided with fine spinules which may serve in seizing and preventing escape of smooth prey.

Plankton-feeder fishes are generally characterized with numerous and elongated rakers.

These rakers carries numerous, fine spinules which are varied in shape.

Rakers serve in straining water current entering pharyngeal cavity for seizing food items.

Chanos chanos fishes characterized from the rest of plankton-feeder fishes wiih their interdigitated rakers.

These inter-digitate rakers form a unique and effective sieve-like structure which serve in retaining of fine food items.

In general, gill rakers of herbivorous fishes is shorter than that of plankton-feeder fishes.

They always carry numerous fine spinules.

They serve as filter which prevent passing of matters attached to the marine plants and sea weeds, to the branchial chambers.

The preceding case also coincides with the case of Scarus blochi; coral-feeding fish.

Rakers on this fish permit the entry of the grinding food matters (items) into the gill cavity.