Gill rakers

Gill rakers are projections from fish gill arches that help protect gill filaments and, in many species, retain food particles as water passes through the mouth and gills.

Branchial arch: A curved skeletal support in a fish's gill region that bears gill filaments and rakers. Gill rakers project from the inner edge of this supporting structure.
Filter feeding: Feeding by straining small organisms or particles from water. Dense rakers can act as a sieve in fishes that consume plankton.
Atlantic menhaden: A schooling North American fish that feeds largely on plankton by filtering water through its gill apparatus. Its feeding anatomy provides a clear example of numerous fine rakers retaining small prey.
Gill arch: A skeletal support in the gill region that bears respiratory and filtering structures. The arch supports rakers but is not itself the comb-like filtering projection.
Gill filament: A thin, vascular structure on a fish gill that carries lamellae for gas exchange. Rakers lie opposite the delicate filaments and can shield them from particles.
Planktivory: A feeding strategy based mainly on consuming plankton. Fine, closely spaced rakers can help retain small planktonic prey.
Manta ray: A large ray that swims with its mouth open to capture plankton from seawater. Its filtering structures demonstrate how modified gill arches can serve suspension feeding.
Gill slit: An external opening through which water leaves the gill chamber in many fishes. A slit is a passage for water, whereas rakers are internal projections that intercept material.
Gill lamella: A thin plate on a fish gill filament where much of the oxygen and carbon dioxide exchange occurs. These gas-exchange surfaces sit behind the rakers and can be vulnerable to debris.
Piscivory: A feeding strategy in which fish eat other fish. Fish that swallow large prey often have fewer, more widely spaced rakers than plankton feeders.

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