Adult Guadalupe fur seals are dark brown or dusty gray with yellowish silver manes, called guard hairs, on the back of the neck.

[3] Guadalupe fur seals are sexually dimorphic in size, as males are much larger and heavier than females; males can grow to about seven feet in length and weigh upwards of 400 pounds, while females are typically only five feet long and weigh about 110 pounds.

Guadalupe fur seals have distinctive ear flaps and large flippers for walking on land, confirming that they are not phocids (true seals) but are more closely related to sea lions.

[7] Guadalupe fur seals are a pelagic species that spend most of their time on the open ocean.

[8] Thus, they dive to catch food and forage for about two weeks before returning to land to feed.

Guadalupe fur seals commonly hunt in shallow water (maximum depth of 250 feet/76 meters) and catch squid, mackerels, and lanternfish.

Guadalupe fur seals create caves on land which can causes social pressures amongst the individuals.

The major cause of the Guadalupe fur seal's decline was commercial hunting in the late 18th and early 19th centuries.