Marine Mammals Archives | Oceana

California Sea Lion

Adult California sea lion females have tan fur, while males have dark brown fur. Females grow to a maximum length of 6.5 feet (2 m) and weigh 242.5 pounds (110 kg) on average. Males are three to four times larger than females, growing to a maximum length of 8.4 feet (2.5 m) and weight of … Read more

Harbor Seal

Harbor seals are members of the true seal or “earless seal” family. Their coats are spotted and a variety of colors, including white, gray, brown and black. Male harbor seals grow to an average length of 5.6 feet (1.7 m) and average weight of 265 pounds (120 kg). Females are smaller than males, growing to … Read more

Minke Whale

“Minke whale” refers to two existing species: the northern, or common, minke whale and the Antarctic minke whale. Aside from the differences in their range, the northern minke whale has a white band on its fin that the Antarctic minke whale does not. Minke whales reach lengths of up to 35 feet long and weigh … Read more

Guadalupe Fur Seal

Guadalupe fur seals are sexually dimorphic, which means males and females have physical differences besides their reproductive systems. Males can grow up to seven feet long and weigh upwards of 400 pounds, while females may only grow up to five feet and weigh up to 110 pounds. Since they are members of the eared seal … Read more

Bearded Seal

The bearded seal is the largest of all Arctic seals, growing to lengths of up to eight feet and weighing 575-800 pounds. These seals tend to weigh the most during winter and early spring when they have an extra layer of blubber under the skin. Sea ice is an important part of the bearded seal’s … Read more

False Killer Whale

Found in open waters throughout the tropics and sub-tropics, particularly surrounding the Hawaiian Islands, false killer whales are considered naturally rare, despite being high on the food chain. One of the most abundant populations of false killer whales can be found offshore from Hawaii and comprises roughly 1,550 individuals. Within these populations, false killer whales … Read more

Gray Seal

The gray seal lives in North Atlantic waters and is divided into three distinct stocks — the North Atlantic stock, the Baltic Sea stock and the eastern North Atlantic stock. In these waters, gray seals experience cold temperatures and sub-arctic environments. Males will come ashore, including onto ice, to mate, often competing with each other … Read more

Bowhead Whale

Baleen whales are known to be some of the largest animals on Earth, and the bowhead whale is no exception. These whales are on average 50 feet long and weigh 60-80 tons. Rows of vertical baleen, or comb-like teeth that help the bowhead strain huge volumes of water to capture food, are the largest of … Read more

Hourglass Dolphin

The hourglass dolphin’s body is short and stocky, while the dorsal fin is tall and curved, sometimes even appearing bent towards the body in adult males. Their body narrows near the mouth where one of the dolphin’s white patches begins, extending over the eye and tapering off at the dorsal fin. The dolphin’s second white patch begins where … Read more


The dugong, like all sea cows, is herbivorous. It primarily grazes on sea grasses and therefore spends most of its time in sea grass beds. Unlike the closely related manatees, the dugong never enters freshwater and is therefore the only exclusively marine mammal that is herbivorous. As in most herbivores, the dugong’s brain is very small compared to … Read more