Category - Anal
Male cartilaginous fishes (sharks and rays), as well as the males of some live-bearing ray finned fishes, have fins that have been modified to function as intromittent organs, reproductive appendages which allow internal fertilization. In ray finned fish they are called gonopodia or andropodia, and in cartilaginous fish they are called claspers. Batoidea is a superorder of cartilaginous fishes commonly known as rays. They and their close relatives, the sharks, comprise the subclass elasmobranchii. Rays are the largest group of cartilaginous fishes, with well over 600 species in 26 families. Rays are distinguished by their flattened bodies, enlarged pectoral fins that are fused to the head, and gill slits that are placed on their ventral. Anal fin origin the most anterior point of the anal fin base andropodium a modification of the anal fin of males of certain live-bearing species in the family goodeidae. It is used to transfer reproductive products to the female during mating. Fish anatomy is the study of the form or morphology of fishes. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. In practice, fish anatomy and fish physiology complement each other, the former dealing with the structure of a fish, its organs or component parts and how they are put together, such as might be. The ray counts in the fins are one of the first identifying factors when classifying a fish. Learning to spot the differences between the spines and soft rays and being able to count them accurately will help narrow down the possibilities for identifying different species. When used for classification, the number of spines are indicated using roman numerals, while the soft rays are indicated. All minnow species have one brief dorsal fin, with nine or fewer soft rays (usually seven or eight). Minnows have well-defined cycloid, or smooth-feeling, scales, which may shed readily from the fish when it is handled. The anal fin is placed farther forward on minnows than it is on suckers. Like all rays, the thornback ray has a flattened body with broad, wing-like pectoral fins. The back is covered in numerous thorny spines, as is the underside in older females. 3 ft) in length, although most are less than 85 centimetres (33 in). A fin can contain only spiny rays, only soft rays, or a combination if the latter, the spiny rays are always anterior. These comments about fin rays also apply to the anal, pectoral, and pelvic fins. Identification the black madtom has a stout body that is black or blue-black above, lighter below, with a pattern of tiny black dots over the body. Dots are most conspicuous on the light underside of the head and belly. The anal fin is long with 21-27 rays and reaches the caudal fin. Pelvic fin occur in pairs and are found on the lower side of the fish below the pectoral fins. Pelvic fins helps the fish in going up, down, turning and stopping.