OBSERVATIONS ON THE BEHAVIOUR OF LIPOTES IN CAPTIVITY

In captivity, the Chinese freshwater dolphin (Lipotes vexillifer) prefers swimming in circles or in the course of " 8 " near the tank wall. During the first twenty days in captivity, it obviously swam anticlockwise, but later on, it swam either clockwise or anticlockwise. Besides normal swimming posture, it also swims on its side and its back. Tumbling, leaping, upright standing and standing upside down, floating or gliding are often observed.The duration of breathing process itself is very short, only about one second. In general, only the melon and the blow-hole are out of water when the animal breathes and its body axis is at an oblique angle to the horizon. Sometimes, spouting begins at about half a meter under water surface, and inhaling is completed when it is gliding with its body axis almost horizontal on the surface. The breathing activity, as a rule, is of slow motion.The duration between spouts is uneven. Following two to four times of short duration (10—30 seconds), there occurs a long duration (50—100 seconds) and the action goes on alternately.The animal began to feed five days after being caught. It swims anticlockwise on its left side toward the prey, with its snout is on the left or right side of the latter. As soon as it approaches the prey it quickly snaps it and adjusts the position of the prey between its jaws so that the head of the victim is pointing backwards. When the dolphin catches a. prey, its body axis is seldom observed in straight line with the latterThe behaviour of the animal in captivity shows different, pattern during the day and the night. In general, in the early morning, the evening, or before feeding, the animal is very active and changes its speed or swimming posture frequently, with short duration of breath. At mid-day and mid-night or after feeding, the animal swims slowly toward one direction with simple swimming posture. Especially at 24 to 4 o'clock, it swims extremely slowly and can be seen gliding slowly on the surface with long duration of breath.