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Whales don’t sleep like humans, instead they rest at the water’s surface or take little naps while swimming. The two halves of their brain are alternatively put to sleep. One half of the brain always remains always active to allow the animal to breathe.
Whale's eyes, always open underwater, are protected from the salty sea water by greasy tears.
Despite their marvels, many whale species are endangered. Find out more below.
Critically endangered species (population low, danger of extinction)
Source: IUCN (The World Conservation Union) Red List
Endangered species
Critically endangered cetacean species (population low, danger of extinction) Source: IUCN (The World Conservation Union) Red List
Fin whale (or Common Rorqual)
This is the second largest animal in the world - only blue whales are larger.
Length: up to 27 metres.
Weight: up to 80 tonnes.
Life span: unknown.
Distribution: worldwide, but not common in tropical seas and polar seas with ice.
Behavior: live in groups of 3-7 individuals. Sometimes migrating in groups of up to 300.
Diet: variety of planktonic animals, crustaceans, squid and fish.
Greenland right whale (or bowhead whale)
Greenland right whales are believed to be the longest-lived animals on earth. They are thought to live for over 100 years. One individual was estimated to be 211 years old. Scientists' suspicions on these whales’ long life spans were raised when harpoon heads, dating back from the early 19th century, were found in whales killed in the 20th century. These whales also have the longest baleens that can reach up to 4.5 metres.
Length: up to 20 metres.
Weight: up to 100 tonnes.
Life span: thought to live for over 100 years. One individual was estimated to be 211 years old (New Scientist report, 2000).
Distribution: exclusively an Arctic species.
Behavior: live in groups of 2-6 individuals. Also found in the company of belugas and narwhals.
Diet: krill in the summer. Live off their body's reserve of blubber in winter.
Humpback whale
The
male humpback whale is famous for its extraordinary songs, which are
the longest and most complex of all wildlife. These submarine
songs, composed by several elements, can last for hours, are
specific to different populations and can be heard hundreds of
kilometres away.
Length: up to 14 metres.
Weight: up to 40 tonnes.
Life span: up to 80 years.
Distribution: Widely distributed in most of the world's oceans. Stocks inhabit both the Southern Pacific and Indian Oceans adjacent to Australia. Some of these stocks migrate up and down the east and west coasts of Australia each year to give birth to their young and mate. Two stocks also inhabit the North Atlantic as well as two in the North Pacific. The healthiest population inhabits the western North Atlantic.
Behavior: live in groups of 2-5 individuals.
Diet: mainly fish.
Northern right whale
These whales lack a dorsal fin.
Length: up to 18 metres.
Weight: up to 80 tonnes.
Life span: unknown.
Distribution: the northern hemisphere, in temperate and sub-polar regions.
Behaviour: live singly or in groups of three to four individuals.
Diet: mainly small crustaceans.
Southern right whale
Like the northern right whales, these whales lack a dorsal fin.
Length: up to 18 metres.
Weight: up to 80 tonnes.
Life span: unknown.
Distribution: the southern hemisphere, in temperate and sub-polar regions.
Behaviour: live singly or in groups of three to four individuals.
Diet: mainly small crustaceans.
Sei whale
Are fast swimmers, reaching speeds of 50km/h.
Length: up to 21 metres.
Weight: up to 55 tonnes.
Life span: up to 75 years.
Distribution: worldwide, except in polar and sub-tropical regions. Occupy temperate and sub-polar regions in the summer.
Diet: krill, small fish and squid.
Vaquita
There are only a few hundred left.
Length: up to 1.5 metres
Weight: up to 60 kg
Life span: unknown
Distribution: exclusively in the Gulf of California.
Behaviour: live in groups of 2-25 individuals.
Diet: squid and fish.
Endangered cetacean species(population low, slowly recovering)
Source: IUCN Red List
Blue whale
The
largest animal ever to have lived - even bigger than any dinosaurs. The
blue whale, with its 12 metre high blow, holds the cetaceans' blow
record. They can eat up to four tonnes of krill per day. That's the
average weight of an African elephant.
Length: up to 33 metres.
Weight: up to 120 tonnes.
Life span: up to 110 years.
Distribution: worldwide, mainly concentrated in the North Atlantic, the North Pacific and above Antarctica in the Southern hemisphere.
Behaviour: live in groups of two to three individuals.
Grey whale
The
grey whale migration is the longest migration of any mammal. Starting
from the west coast of Mexico (winter reproduction zones), it
travels along the north American west coast up to the Bering sea
(summer feeding zones) and then returns.
Distance covered:
between 12,000 and 20,000 km. After its 40 years of life, a grey whale
has consequently covered a total distance corresponding to an earth -
moon return trip. They eat about 150 tonnes of food during a 140 day
feeding period. That represents a daily average of about 1090 kg.
Length: up to 15 metres.
Weight: up to 35 tonnes.
Life span: unknown.
Distribution: restricted to the North Pacific, along east and west coasts.
Behaviour: live in groups of two to three individuals.
Diet: they feed along the oceans floor, collecting crustaceans and marine worms.
Other whale species’ facts
Sperm whale
The
sperm whale is the deepest diving cetacean. It can reach depths of more
than 2,000 meters. Sperm whales can weigh up to 45 tonnes, and have the
heaviest brains on earth – weighing up to 9kg. The average human brain
weighs 1.4 kg.
Killer whales
Killer whales are incredibly fast. In the North-Eastern Pacific, some killer whales have reached speeds over 55 km an hour. Their fins can reach up to 1.80 metres high - as tall as a human adult.
Greenland Right Whale, Humpback Whale and Sei Whale photos courtesy of http://www.seapics.com
Image © Gary Bell 2004/Oceanwide Images
