<Li> a projecting, modified (rough and strongly ridged) scale, usually associated with the lateral line, or on the caudal peduncle forming caudal keels, or along the ventral profile . Some fish, such as pineconefish, are completely or partially covered in scutes . </Li> <P> The lateral line is a sense organ used to detect movement and vibration in the surrounding water . For example, fish can use their lateral line system to follow the vortices produced by fleeing prey . In most species, it consists of a line of receptors running along each side of the fish . </P> <P> Photophores are light - emitting organs which appears as luminous spots on some fishes . The light can be produced from compounds during the digestion of prey, from specialized mitochondrial cells in the organism called photocytes, or associated with symbiotic bacteria, and are used for attracting food or confusing predators . </P> <P> Fins are the most distinctive features of fish . They are either composed of bony spines or rays protruding from the body with skin covering them and joining them together, either in a webbed fashion as seen in most bony fish or similar to a flipper as seen in sharks . Apart from the tail or caudal fin, fins have no direct connection with the spine and are supported by muscles only . Their principal function is to help the fish swim . Fins can also be used for gliding or crawling, as seen in the flying fish and frogfish . Fins located in different places on the fish serve different purposes, such as moving forward, turning, and keeping an upright position . For every fin, there are a number of fish species in which this particular fin has been lost during evolution . </P>

Where is the brain of a fish located