<P> Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch (gill arch) and are involved with suspension feeding tiny prey . They are not to be confused with the gill filaments that compose the fleshy part of the gill used for gas exchange . Rakers are usually present in two rows, projecting from both the anterior and posterior side of each gill arch . Rakers are widely varied in number, spacing, and form . By preventing food particles from exiting the spaces between the gill arches, they enable the retention of food particles in filter feeders . </P> <P> The structure and spacing of gill rakers in fish determines the size of food particles trapped, and correlates with feeding behavior . Fish with densely spaced, elongated, comb - like gill rakers are efficient at filtering tiny prey, whereas carnivores and omnivores often have more widely spaced gill rakers with secondary projections . Because gill raker characters often vary between closely related taxa, they are commonly used in the classification and identification of fish species . Much of the variation in gill raker morphology is thought to be due to adaptation to optimize the consumption of different diets . </P>

What is the function of the gill rakers of a perch