Arctocephalus galapagoensis
Galápagos fur seal

Arctocephalus galapagoensis are found only in the Galapagos Islands, they do not migrate (Gentry & Kooyman, 1986).

Southern fur seals live only on the Galapagos Islands and in the surrounding waters. Air temperature is fairly constant year round at an average of 23.8 degrees C (Trites, 1990).

Male southern fur seals are 154 cm long, while the females are about 120 cm long. Although there is a 30 cm difference, it is the least sexually dimorphic of otariids in size and in color. Dorsal body surface is gray-brown, the venter is light tan. Arctocephalus galapagoensis is the smallest of the fur seals, possibly an adaptation to the warm ambient and aquatic temperatures of their tropical habitat (Wartzok, 1991).

Southern fur seals are the most terrestrial species of the family Otariidae (Limberger, 1986), spending only 70% of their life in the water. Females dive for an average of 16.4 hours to a depth of no more than 30 meters at night, but deeper dives have been recorded (Gentry & Kooyman, 1986; Trillmich, 1985). Nowak (1999) states that "foraging trips have been found to last 50-70 hours at the time of the new moon but only 10-20 hours at the time of the full moon". During the warm months, females will repeat a foraging cycle of 4-6 days in the water and 1 day on land (Nowak, 1999). After giving birth, females will leave their pups for 1-3 days to dive for food then 1-2 days are spent with the offspring. Pups do not become independent until their 2nd year, and sometimes not until their third (Nowak, 1999). Adult males hold territories that can extend 200 square meters (Bowen, 1991; Nowak, 1999). Males defend these territories with high levels of aggression. Death rate for fighting males is 30% annually (Miller, 1991). Females hold very small areas, compared to other fur seals, of approximately 100 square meters. They are a polygynous species and males do not offer care for the offspring (Nowak, 1999). Males do not feed while they are defending their territories, and will not abandon them until they have used all of their stored energy and have no choice but to feed (Wartzok, 1991).

These territories encompass water and rough terrain with overhangs to provide cooling. Other seals do not occupy this type of terrestrial habitat, most other seals prefer beaches (Nowak, 1999).

To keep cool, seals will move to tide pools and wet themselves. Females have to teach this thermoregulatory strategy to their pups, or the newborns will suffer from overheating (Limberger, 1986). It is very important at this latitude to keep internal temperatures to approximately 37.7 degrees C (Limberger, 1986), therefore these seals have evolved methods to accomplish this. They utilize their environment for shade and water cooling, and have a reduced body size to release heat quickly. They also sweat, depending on individual hydration (Limberger, 1986). Much heat loss is controlled internally by the cardiovascular system in that blood flow is directed away from, or toward, flippers depending on whether the seal is too cold or too warm, respectively (Trites, 1990).

Arctocephalus galapagoensis feeds on fish and cephalopods. (Nowak, 1999; Reidman, 1990)

Arctocephalus galapagoensis were previously hunted for their furs.

Ecuador provides protection by law for southern fur seals.

By the early 1900s it was said to be extinct due to overhunting for fur, but a population was found in 1932-33. The population had increased to between 30,000 and 40,000 by 1989. Ecuador reports that feral dogs on some of the 15 Galapagos Islands are a threat to current seal populations (Nowak, 1999).