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Cetaceans | Pinnipeds | California Sea Otter


Marine Mammals at Piedras Blancas

By Carole Adams


Marine mammals decended from land mammals developing, over a long period of time, physical adaptations enabling them to live at sea. They breathe air, are warm blooded, give birth to live young, and suckle their young. Marine mammals probably entered the sea to find food or escape predators.


There are three types of marine mammals on California's central coast:


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.

graywhaleBottom 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.

FESThe 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.

bottle nose dolphinThe 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 killer whales are seen.


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

baleen whale toothed whale

Baleen instead of teeth
Double blowhole
Females larger than males

Have teeth, not baleen
Single blowhole
Males larger than females



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 two main groups of local pinnipeds are:

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.


PinnipedsCalifornia sea lions are usually visible on the Outer Islet at Piedras Blancas. Stellar sea lions and orthern 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):

earless seal eared seal

No external ear flaps
Neck not elongated
Short fore-flippers
Move by hunching forward on land
Swim with hind-flippers


Tiny external ear flaps

Elongated neck

Long fore-flippers
Can "walk" on all flippers
Swim with fore-flippers

FESCalifornia Sea Otters

Mustelidae: Sea otters are members of the weasel family. They are more closely related to landcarnivores 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.


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Photo contributions by Phil Adams, Joan Crowder, Peter Hemming, Brandt Kehoe, Tim Postiff & Nancy McKarney