BIOL 337 Lecture Notes - Lecture 1: Actinopterygii, Swim Bladder, Pylorus
Document Summary
Consider the body morphology, colouration and spot patterns. Then, observe the lateral line be sure to know its function. The skin contains glands emitting mucus which keeps the scales slippery and flexible (as an angler knows to his cost) and also acts as an anti-septic, protecting the fish from bacterial infection. The scales grow in the dermis, the inner layer of the skin, and are covered by a fine epidermis or outer skin layer: each scale fits into its own little pocket of epidermis. They are usually more or less rounded in outline: cycloid scales have smooth edges, while ctenoid scales have a spiked or serrated trailing edge. The scales grow by adding rings around the edge; they grow fast in summer but little in winter, and thus leave seasonal growth lines by which the age of the fish can be estimated. Symmetrical caudal fins, fewer bony rays in fin membranes, less dermal armour greater flexibility in fins and mobility.
