CHAPTER VI
VERTEBRATES
A. Studies of Fishes
THE LIVING FISH
Vertebrates adapted to Water Life
Materials.
Living goldfishes or other fishes in small aquaria for individual study and a few fishes in a large aquarium where they have considerable freedom of motion.
Definitions.
Trunk, the portion of the body between the head and the tail. Compressed, a term used to describe the shape of the body when it is narrower from side to side than from dorsal to ventral surface. When the opposite is true, the body is said to be flattened. Median fins, the unpaired fins situated on the median line, dorsal and ventral, including the tail or caudal fin, the dorsal fin, and the anal fin. Paired fins, fins occurring in pairs of which the more anterior are the pectoral fins and the posterior are the pelvic fins. Fin rays, the framework or skeleton of the fins over which membrane is stretched to form the fins. Fin rays are of two kinds: those composed of bone and those composed of cartilage. Lateral line, a sense organ extending along each side of the fish in a line indicated by tubes or perforations in the scales. Gills, respiratory organs adapted for taking oxygen from the water. Operculum, the flaps covering the gills on each side of the head. Pigment, a substance which gives color to an object.