Cichlid - Anatomy and Appearance

Anatomy and Appearance

Cichlids share a single key trait: the fusion of the lower pharyngeal bones into a single tooth-bearing structure. A complex set of muscles allows the upper and lower pharyngeal bones to be used as a second set of jaws for processing food, allowing a division of labor between the "true jaws" (mandibles) and the "pharyngeal jaws". Cichlids are efficient feeders that capture and process a very wide variety of food items. This is assumed to be one reason why they are so diverse. Cichlids vary in body shape, ranging from compressed and disc-shaped (such as Symphysodon), to triangular (such as Pterophyllum), to elongate and cylindrical (such as Crenicichla).

The features that distinguish them from the other Labroidei include:

• A single nostril on each side of the forehead, instead of two.
• No bony shelf below the orbit of the eye.
• Division of the lateral line organ into two sections, one on the upper half of the flank and a second along the midline of the flank from about halfway along the body to the base of the tail (except for genera Teleogramma and Gobiocichla).
• A distinctively shaped otolith.
• The small intestine's left-side exit from the stomach instead of its right side as in other Labroidei.