Walrus Case Study

Reproduction: On the average, walrus males reach their sexual maturation at about eight to ten years of age, but they typically mate at 15 years old when they are strong enough compete for females. On the other hand, most females are sexually mature at about five to six years. However, successful reproduction begins at about ten years of age. The breeding begins when herds of non-pregnant, estrous females meet male herds and move to the mating place which is the central and south Bering Sea in case of the Pacific. Ice-bound group of estrous females is aggregated by nearby in-water adult males, which may perform competitive vocal displays including bell-like sounds, under water clicks, teeth clacking and whistles at the water surface. Females

Mother’s milk is occasionally supplemented with a small amount of solid food as early as six months of age. Males grow slightly faster than females. During nursing, a female mother defends and protects her calf and may shelter it under her chest between her foreflippers. Young female calves usually remain with their mother's herd while young males may stay for additional two or three years before joining an all-male herd. Adaptations of walruses for aquatic environments

Diving: Walruses can stay submerged for up to 10 minutes. The diving depth of walruses stay within 80 m which is water depth they inhabit. Walruses are physiologically adopted to conserve oxygen while diving through: Slowing down the heart beating Blood is shunted away from tissues tolerant of low oxygen levels toward organs where oxygen is needed, such as the heart and brain Muscles have a high content of the oxygen-binding protein myoglobin Thermoregulation The heat gradient throughout the thick blubber (up to 10 cm) to the skin slows heat loss in the water during the winter and hence makes the skin warmer than the water by about 1° to 3°C. In cold water, blood is shunted inward as blood vessels in the skin narrow to reduce the heat loss to the environment; the skin then appears pale, almost white. When warm, blood vessels in the skin