Marine mammals were once land mammals that, over a long period of time, developed physical adaptations enabling them to live at sea. Like all mammals they breathe air through lungs, are warm blooded, give birth to live young and suckle their young. Most have hair, at least at some time in their lives. Marine mammals probably entered the sea to find food or escape predators.

There are three types of marine mammals seen from Piedras Blancas:

• Cetaceans, which includes whales, dolphins and porpoises.
• Pinnipeds, which includes both eared and earless seals.
• The California sea otter

Cetaceans

Cetaceans have completely adapted to a life at sea. They feed, mate, bear and suckle their young at sea. All cetaceans have pectoral fins (flippers). They lack rear appendages but have powerful flukes that move up and down to propel them through the water. A layer of blubber, just below the skin, helps maintain body temperature. Although they may have a few whiskers on their faces, they have lost their fur coats.

Cetaceans (whales, dolphins, porpoises) are categorized into two groups: baleen whales (mysticetes) and toothed whales (odontocetes.)

Baleen whales (mysticetes): Baleen is used to filter food from the water. Plates of fringed baleen hang down from the upper jaw of the mysticetes, like curtains or overlapping rows of combs that strain food from the water. Baleen is made of keratin, a substance that is similar to the human fingernail. All baleen whales have double blowholes (nostrils). The females are generally larger than the males.

Baleen whales are further categorized according to the method of feeding they use: gulping, skimming, or bottom feeding:

Engulfing or gulping: The blue whale and the humpback whale use the engulfing, or gulping, method of feeding. Numerous throat grooves, or pleats, allow for expansion of the throat when feeding. Huge quantities of water containing prey are taken in. The baleen acts as a filter trapping food when the water is expelled. Whales with numerous throat grooves are referred to as rorquals.

Skimming: The bowhead and right whales utilize a different feeding style. They are skim feeders, using their baleen to filter prey from the surface of the water. Their baleen plates are quite long, up to 12 feet long in the bowhead whale. These whales do not have throat grooves

Bottom feeding: The gray whale is unique among baleen whales in that they predominately engage in bottom feeding. They suck in sediment containing small shrimp-like crustaceans from the bottom of the shallow arctic seas. Using their powerful tongues they expel the water and sediment, trapping the food inside the baleen. Although this bottom-suction method is their primary feeding strategy, they have also been observed using the gulping and the skimming methods.

The baleen whales most likely to be seen from Piedras Blancas are the gray whale and the humpback whale. Occasionally blue whales or minke whales are seen.

Toothed whales (odontocetes): The toothed whales include dolphins, porpoises, and the sperm whale. They use their teeth for grabbing and piercing, not for chewing. They swallow prey whole or tear it into pieces.

Toothed whales have single blowholes and the males are larger than the females. Echolocation is common among toothed whales. During echolocation, high-frequency sounds are produced and transmitted, which bounce off objects and the returning sound wave, or "echo", provides information.
The best way to tell a dolphin from a porpoise is by tooth shape. Dolphins have conical teeth and porpoises have spade-shaped teeth. Other differences are that dolphins usually have a beak and usually have a falcate (curved) dorsal fin, although some have none. Porpoises never have a beak and usually have a triangular dorsal fin, although some have none.

The toothed cetacean that is most likely to be seen from Piedras Blancas is the bottlenose dolphin. Occasionally orcas (killer whales) are seen.

Comparison of a baleen whale (humpback) and toothed whale (orca):

Pinnipeds

Pinnipeds have adapted to a life at sea but they come ashore at times to mate, give birth, molt, and rest. They have to be able to survive in both marine and terrestrial environments.

The three main groups of pinnipeds are the eared seals, the earless seals, and the walrus.

Eared seals (otariids): Eared seals are easily identifiable by tiny external earflaps. They have an elongated neck and use their front flippers for propulsion and their hind flippers for steering. They are agile on land and are quadrupedal (use four-legged movement). The males are about twice as big as the females and develop thickened necks and bumps on their heads called sagital crests. The young may be dependent for a year or more. The eared seals include sea lions and fur seals.

California sea lions are usually visible on the Outer Islet at Piedras Blancas. Stellar sea lions and northern fur seals are rarely seen.

Earless seals (phocids): The earless seals have no external ear flaps and short necks. They can not pull their hind flippers around on land and walk like eared seals; rather, they heave their bodies forward like a caterpillar. Even though they are not agile on land they are graceful swimmers, using their rear flippers for propulsion (in a side-to-side movement) and their front flippers for steering. Sexual dimorphism is rare, except in the elephant seal. With that exception, males and females are generally similar. Pups grow very fast and are weaned young. The phocids include the harbor seal and the elephant seal. Earless seals are also referred to as true seals.

Harbor seals and elephant seals are the commonly seen earless seals in the Piedras Blancas area.

Comparison of an eared seal (California sea lion) and an earless seal (harbor seal):

Walrus: The walrus combines traits of both the phocids and the otariids. They have no external ear flaps but move quadrupedally on land. The tusks are present in both sexes. Walruses live principally in arctic regions - they are not seen at Piedras Blancas.

Sea Otters

Mustelidae: Sea otters are members of the weasel family. They are more closely related to land carnivores than either pinnipeds or cetaceans and they are the most recently evolved marine mammal. They have completely adapted to marine life - they rest, mate, give birth, and suckle their young at sea, although they may at times come on land. Their hind limbs are webbed for swimming, but their front paws are padded and have clawed digits, more reminiscent of land animals.

The California sea otter, or southern sea otter, is frequently seen at Piedras Blancas.

More on Marine Mammals

There are many more species of cetaceans and pinnapeds than can be presented here and the material above includes no reference to sirenia (manatees, dugongs, and sea cows) or to polar bears. The classification of marine mammals can be viewed by clicking on the image to the right and further information is available from the Marine Mammal Commission, NOAA, and the National Marine Mammal Laboratory.