The word cetacean is used to describe all whales, dolphins and porpoises in the order Cetacea. This word comes from the Latin ‘cetus’ meaning “a large sea animal” and the Greek word ‘ketos’, meaning “sea monster”.
There are 86 species of cetaceans and these are divided into two main groups: the baleen whale (Mysticetes) and the toothed whales (Odontocetes). There are 14 species of baleen whales and 72 species of toothed whales .
Baleen whales are generally larger than the toothed whales. The largest animal in the world, the Blue Whale is a baleen whale. But there are exceptions (e.g. the Sperm Whales and Bairds Beaked Whale). Baleen Whales feed on smaller fish and plankton and Krill with a filtering system made up of hundreds of baleen plates. They tend to be solitary, although occasionally gather in groups to feed or to travel.
They have two blowholes on top of their heads, one right next to the other. Female baleen whales are also larger than males of the same species. Examples of baleen whales include the Blue Whale, Fin Whale and Humpback Whale.
Baleen Whales feed by gulping large amounts of water containing hundreds or thousands of fish or plankton, then forcing the water out in between the baleen plates, leaving the prey inside to be swallowed whole.
Toothed whales include the Sperm Whale, Orca (or killer whale), Beluga and all of the dolphins and porpoises.
The toothed whales have a much stronger social structure than baleen whales, often gathering in pods with a stable social structure. They have one blowhole on the top of their head.
Toothed whales are predators that have cone-shaped or spade-shaped teeth and usually capture one animal at a time and swallow it whole. Odontocetes feed mostly on fish and squid but Orcas will also take creatures up to the size of sea lions and other whales!
Cetaceans are mammals, which means they are endothermic (commonly called warm-blooded) and their internal body temperature is about the same as a human’s. They give birth to live young and breathe air through lungs just like we do. They even have hair.
Unlike fish, which swim by moving their heads from side to side, to swing their tails, cetaceans propel themselves by moving their tails in a smooth, up and down motion.
Some cetaceans, such as the Dall’s porpoise and the Orca (killer whale) can swim faster than 30 miles per hour.
When a cetacean wants to breathe, it has to rise to the water surface and exhale and inhale out of the blowholes located on top of its head. When the cetacean comes to the surface and exhales, you can sometimes see the spout, or blow, which is the result of the warm air in the whale’s lungs condensing upon reaching the cool air outside.
Whales do not have a coat of fur to keep warm, so they have a thick layer of fat and connective tissue called blubber underneath their skin. This blubber layer can be as much as 24 inches thick in some whales.
Whales have a poor sense of smell, and depending on where they are, they may not be able to see well underwater. However, they have excellent hearing. They do not have external ears, but have tiny ear openings behind each eye. They can also tell the direction of sound underwater.
Whales have collapsible rib cages and flexible skeletons, which allows them to compensate for high water pressure when they dive. They can also tolerate higher levels of carbon dioxide in their blood, allowing them to stay underwater for up to 1 to 2 hours for large whales.
THREATS TO WHALES
Whaling. The main cause of decline in whale numbers historically was industrial whaling – killing whales for their meat and oil. It drove some species to the brink of extinction. Commercial whaling was banned in 1986 by the International Whaling Commission (IWC), the inter governmental body responsible for whale conservation and whaling management. But whale populations still haven’t recovered.
Whales can still be hunted for ‘scientific purposes’. For example to understand their biology. Japan is one such country doing this – whilst trying to fuel a market for whale products. It’s believed that science permits are sometimes used simply as a disguise for commercial whaling.
Climate Change is an emerging threat which is affecting stocks. Global warming is causing Arctic Sea ice to melt, making areas that are important for some whales more accessible for oil and gas development, which can cause a number of problems for whales and their environment. Climate change is also depleting some important food sources for whales – such as Krill, which breed under sea ice.
Bycatch. Like many marine animals, whales are at risk of Bycatch – accidental entanglement in fishing gear, which can cause injury infections, starvation and drowning. Its estimated 300,000 whales, dolphins and porpoises die this way each year. Whales are also vulnerable to collisions with ships, which can seriously injure or even kill them.
LIST OF THE WORLD’S TEN MOST ENDANGERED WHALE SPECIES
THE SOUTHERN RIGHT WHALE – some better news!
The Southern Right Whale is a Baleen whale and one of three species classified as Right Whales.
Land based whaling in Australia initially concentrated on Southern Right Whales. They get their name because they were the ‘right’ whale to catch: they were slow swimming, floated when dead and provided large amounts of valuable products – particularly oil for illumination and lubrication.
Commercial whaling began in Australia in 1820 taking around 75% of the population of Southern Right Whales between 1835 and 1845, when the industry collapsed. It took 90 years before they were officially protected.
An estimated 12,000 Southern Right Whales are spread throughout the southern hemisphere – compared to an original number of more than 100,000. Their numbers are growing at 7% per annum.
These days Southern Right Whales delight whale watchers on the New South Wales coastline ‘performing’ breaching and headstands. Southern Right Whales can be found in very shallow water including estuaries and bays. They have never been known to strand.
Southern Right Whales facts:
THE BLUE WHALE
The Blue Whale is the largest creature ever to have lived on earth. They can grow up to 100 feet long, or the equivalent of three double-deck buses joined end to end!
Their tongues alone can weigh as much as an elephant. Their hearts as much as a car!
They can consume 2-4 tons of krill a day.
Although we can’t hear them,the blue whales are one of the loudest animals on the planet , communicating with each other using a series of low frequency pulses, groans and moans. It is thought that in good conditions whales can hear each other over distances of 1,600 km.
Scientists think they use these vocalizations not only to communicate, but, along with their excellent hearing, to sonar-navigate the dark deep oceans.
The Blue Whale is blue-grey in colour with an underside of yellowishgreen caste. The whale acquires micoorganisms called diatoms in the cold water of the Antarctic and Nth Pacific and North Atlantic and they are the cause of the colouration . Early whalers referred to blue whales as ‘sulphur-bottoms’.
Females breed once every three years and gestation is about a year. Calves drink huge quantities of their mothers milk, (although researchers seem to disagree on the actual amount! ) from 200 litres a day (The Marine Mammal Center), 379 litres (The American Cetacean Society) and 600 litres (One Kind).
Whaling decimated the Blue Whale population in the 1900s. In 1931 at its peak, 29,000 blue whales were killed. Prewhaling population estimates were over 350,000 blue whales, but up to 99% of blue whales were killed during whaling efforts. Presently most reports say there are less than 25,000 blue whales left in the World, but some, The Marine Mammal Center for example, as few as 9000, maybe less!
THE ORCA ( KILLER WHALE )
The Orca is a toothed whale (Odontocetes). It’s the largest member of the dolphin family. It is highly social and composed of matrilineal family groups. Orcas feed on fish, squid, birds and marine life up to the size of blue whale calves. They use echolocation-bouncing sound off of objects to determine their location, to hunt and use a series of high-pitched clicks to stun prey. Orcas are highly social animals that travel together in groups called pods. Members of Orca pods very often work together to catch a meal. Pods usually consist of 5-30 whales, although some pods may combine to form a group of 100 or more. Orcas establish social hierarchies, and pods are led by females. The animals are thought to have a complex form of communication with different dialects from one another. Many Orcas live with their mothers for their entire lives.
PLEASE READ this article concerning Gabriela Cowperthwaite’s astonishing documentary, Blackfish.
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