Cetaceans

Cetaceans are entirely aquatic mammals. Their body structure has undergone many evolutionary changes from that of the ancestral land mammals. The hind limbs are absent, fore limbs are adapted to flippers, and the tail has evolved into horizontal flukes. The skin is smooth and lacks fur or hair. Breathing is through a blowhole on the top of the head.

Suborders Cetacia

 

Characteristics of Baleen Whale

Right whale group, including the right and bowhead whales.

• Adults are up to 50-60 feet long and average bowhead weight is more than 75 tons.
• Long baleen (often more than 10 feet long)
• Massive head
• No dorsal fin
• Eat zooplankton predominantly, especially copepods and euphausids.
• Northern right whales (which got this name from whalers who considered them the “right” whale to kill) are critically endangered, with as few as 200 animals each surviving in the North Pacific and North Atlantic, perhaps below the minimum population for survival. Southern right whales are endangered but have a population of 3000-5000 animals.
• The bowhead whale is also endangered, with a population of about 7500 in western and northern Alaskan waters. It is hunted for subsistence use by Alaska Natives.

Mysticeti	Odontoceti
(toothed whales)	(baleen whales)
All are carnivores.	All are carnivores.
All are filter feeders, that strain zooplankton from huge mouthfuls of water using 100s of baleen “plates” that hang from the upper jaw.	All are predators that pursue and capture their prey.
Includes: Right whales Rorquals Gray whale	Includes: Sperm whale Beaked whales Dolphins Porpoises Beluga Narwhal

Rorquals

include the blue whale (the largest animal ever to live on Earth), the fin whale, the sei whale, the minke whale, and the humpback whale.

·         The largest group of whales (and animals) on earth, ranging from the Minke (adults average 27 feet long and 7 tons) to the blue (average adult 85 feet long and 100 tons).

• Short baleen, only 2 or 3 feet long.
• Ventral throat grooves that expand to allow intake of huge volumes of water.
• Small dorsal fin.
• Eat zooplankton and small, schooling fish (up to 4 tons/day for the blue whale).
• The blue whale has the lowest population, about 12,000 worldwide, and is the most endangered of this group. All species except the Minke are listed as Endangered.

 

Gray whales are a single species, with subpopulations in the western and eastern Pacific; the eastern population is larger. Gray whales were once found in the Atlantic, but are now extinct there.

• Average adults are 46 feet long and 33 tons.
• Short baleen, only about 6” long.
• No dorsal fin.
• Feed by dredging through mud, scooping mud and water into their mouths, and filtering out benthic amphipods and other small bottom animals.

Hunted to near-extinction in the 1930s, they are now considered Recovered

Characteristics of the Toothed Whales

Sperm whale

• The largest toothed whale at 50 feet and 40 tons.
• Huge, square head.
• Small dorsal fin.
• Deepest- and longest-diving cetacean, for up to 90 minutes and to depths of 10,000 feet.
• Eat squid, preferring giant squid, and fish.
• Worldwide population of about 1.5 million, but still listed as an Endangered species.

Beaked whales include the Cuvier’s, Baird’s, and Stejneger’s beaked whales. These whales are rarely observed, since they mostly remain in deep water and appear to avoid ships, so little is known about them.

• The Stejneger’s whale is smallest (16 feet long and 1.3 tons), the Baird’s whale the largest (34 feet, 10 tons).
• Beak similar to that of dolphins.
• Small dorsal fin.
• Probably eat mainly squid.
• The population is unknown. The Baird’s beaked whale is the only species deliberately hunted by man.

Dolphins include the orca (killer whale) and Pacific white-sided dolphin in Alaskan waters, and many other species worldwide.

• Most are small (7 feet,
• 300 pounds), but the female orca averages 23 feet and 4 tons, males 26 feet and 8 tons.
• Have a beak, relatively large dorsal fin (especially male orcas)
• Have a “melon”.
• Have conical teeth.

• Eat fish and squid; the orca also eats seals, sea lions, sea otters, and sometimes other whales.
• Not listed as Endangered. Sometimes killed in fishing nets.

Porpoises include the Dalls and harbour porpoises in Alaskan waters, many others worldwide.

• Dalls is 6 feet and 300 lbs., harbour 5 feet and 120 lbs.
• No beak, relatively large dorsal fin.
• Spade-shaped teeth.
• Eat fish and squid.
• Not Endangered. Sometimes killed in fishing nets.

Belukha, the white whale

• Averages about 12 feet long and 3000 lbs.
• Short beak and large “melon”. No dorsal fin.
• Conical teeth.
• Eat fish, squid, and probably anything else they can catch.

Not currently endangered, but the Cook Inlet population seems to have declined. Population estimated at 70,000 worldwide.

Echolocation

Many marine animals use sound to locate prey, to avoid obstructions, and to communicate. Echolocation is specifically the use of sound to locate objects, usually food. Echolocation is particularly well-developed in the toothed whales, but may be used by some baleen whales also. The sound is generated by the blowhole (often focused by the “melon”) and received by the jaw, thereby channeled to the middle ear.

Whaling and its Regulation

European whaling was recorded as early as 800-1000 A.D. Inuit and other native peoples hunted whales long ago. However, the focus of this page is on European, American, and Asian whaling of the 19^th and 20^th centuries, since the this whaling industry endangered many whale species.

Before 1867, all whaling was done with hand-held harpoons. It was a fairly even contest between man and whale.

In 1868 the harpoon gun was invented. But, whales could be hunted only close to shore, because they could not be butchered at sea.

By 1925 “factory” ships made it possible to process whales killed far from shore.

During the 1930s, several species, including the right, bowhead, and gray, were hunted nearly to extinction.

In 1946 the International Whaling Commission (IWC) was established and the gray, bowhead, and right whales were protected. However, whaling of other species continued. The IWC had little power to enforce regulations.

In 1962-63, the peak years of whaling, >60,000 whales were killed.

In 1972 the Marine Mammal Protection Act ended whaling in U.S. waters or by U.S. vessels.

In 1982 the IWC passed a moratorium on whaling that took effect in 1985-86, with some exceptions for “scientific” whaling by Japan, Norway, Iceland, the USSR, and Korea. Although the IWC ban continues, Japan and Norway currently harvest minke whales. The IWC also permits subsistence whaling for traditional uses by native peoples. 

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