Meristic character

Meristic character is a term used in the scientific classification and identification of marine organisms.

Meristic means having a number of parts, or divided into serially repeated, countable features, e.g. the rays in a fish fin, the myomeres of an eel larva, the rakers on a fish gill arch, photophores, scutes, finlets, branchiostegals, and also to other structures that can be counted, e.g. pyloric caeaca, etc.

Meristic characters are the countable structures occurring in series (e.g. myomeres, vertebrae, fin rays) in fish. These characters are among the characters most commonly used for differentiation of species and populations. In the salmonids, scale counts have been most widely used for the differentiation of populations within species. In rainbow and steelhead trout the most notable differences among populations occur in counts of scales.