World of whales

 Why are whales special?

Whales are social, air breathing mammals, they feed their babies with their own milk, and they take extraordinarily good care of their young and teach them life skills.

Many of us believe whales are special; they certainly invoke a sense of wonder and a feeling of kinship. There is something almost other-worldly about them. Whales enrich the lives of many people who come into contact with them. Whales are unique, beautiful, graceful and mysterious; they nurture, bond, play, sing and cooperate with one another. Here are some extraordinary facts about whales and their lives in the oceans.

There are currently around 90 recognised species of whales, dolphins and porpoises; they are collectively known as ‘cetaceans’ or simply ‘whales’. There are 15 baleen whales, 3 sperm whales, 23 beaked whales, 2 monodontidae (narwhal and beluga), 42 dolphins (including 4 river dolphins) and 7 porpoises.

Cetaceans are broadly divided into two groups, depending on whether they have teeth (odontocetes) or baleen (mysticetes).

Baleen whales, such as the blue whale, are sometimes called the ‘great whales’ due to their overall larger size. There are 15 baleen whales altogether: these whales have baleen plates in their mouths to sift their food - plankton, krill (little shrimps) and small fish - from seawater.

Toothed whales account for all the remaining species of whales, dolphins and porpoises and they all have varying numbers of teeth. Toothed whales eat mainly larger fish, squid, octopus and at times, other marine mammals.

So which cetaceans do we call ‘whales’? It isn’t very scientific but whales include all the baleen whales and the larger toothed whales such as the sperm whale, beluga, narwhal, and the beaked whales.

Baleen whales and toothed whales feed very differently. Baleen whales extract their prey from seawater as it flows through, or is forced through their baleen plates using their tongues and sometimes their throat muscles. They eat mainly small shrimplike krill, copepods and fish.

Did you know that baleen is made out of keratin, the same protein that makes up our fingernails and hair? It is very strong and flexible. Hundreds of overlapping baleen plates grow downwards from the roof of the whale’s mouth, like multi-layered curtains. The number, size and colour of the baleen plates are unique for each whale species.

Baleen whales are all essentially filter feeders but their feeding techniques vary; the humpback and blue whale are gulpers – they open their mouths wide and gulp enormous mouthfuls of seawater, their prey gets caught amongst the baleen plates as the seawater is pushed back out through them. Bowhead and right whales are skim feeders, they swim along with their mouths half open, allowing sea water to flow through their baleen and trap plankton. Gray whales swim on their sides along the bottom of the ocean floor and suck up mud and water; they use their baleen to filter out tiny crustaceans from this sludge.

Toothed whales (and dolphins and porpoises) all have teeth - the number, size and position of their teeth varies from species to species. They hunt mainly fish, squid and octopus using their sophisticated sonar systems – echolocation – to find and target their prey. Toothed whales generally use their teeth to grab and hold on to their prey before swallowing it. Some may also use their teeth for tearing and breaking up prey. Some beaked whales have only two to four teeth, they are squid eaters and are thought to suck in squid and swallow them whole.

Dolphin world

 

What is a Dolphin?

A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the brackish dolphins), and the extinct Lipotidae (baiji or Chinese river dolphin). There are 40 extant species named as dolphins.

Dolphins range in size from the 1.7-metre-long (5 ft 7 in) and 50-kilogram (110-pound) Maui's dolphin to the 9.5 m (31 ft 2 in) and 10-tonne (11-short-ton) orca. Various species of dolphins exhibit sexual dimorphism where the males are larger than females. They have streamlined bodies and two limbs that are modified into flippers. Though not quite as flexible as seals, some dolphins can briefly travel at speeds of 29 kilometres (18 mi) per hour or leap about 30 feet (9.1 m).Dolphins use their conical teeth to capture fast-moving prey. They have well-developed hearing which is adapted for both air and water. It is so well developed that some can survive even if they are blind. Some species are well adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water.

Dolphins are widespread. Most species prefer the warm waters of the tropic zones, but some, such as the right whale dolphin, prefer colder climates. Dolphins feed largely on fish and squid, but a few, such as the orca, feed on large mammals such as seals. Male dolphins typically mate with multiple females every year, but females only mate every two to three years. Calves are typically born in the spring and summer months and females bear all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively long period of time. Dolphins produce a variety of vocalizations, usually in the form of clicks and whistles.Dolphins are sometimes hunted in places such as Japan, in an activity known as dolphin drive hunting. Besides drive hunting, they also face threats from bycatch, habitat loss, and marine pollution. Dolphins have been depicted in various cultures worldwide. Dolphins occasionally feature in literature and film, as in the film series Free Willy. Dolphins are sometimes kept in captivity and trained to perform tricks. The most common dolphin species in captivity is the bottlenose dolphin, while there are around 60 orcas in captivity.

more about dolphins:

The name is originally from Greek δελφίς (delphís), "dolphin",^[2] which was related to the Greek δελφύς (delphus), "womb".^[2] The animal's name can therefore be interpreted as meaning "a 'fish' with a womb".^[3] The name was transmitted via the Latin delphinus^[4] (the romanization of the later Greek δελφῖνος – delphinos^[2]), which in Medieval Latin became dolfinus and in Old French daulphin, which reintroduced the ph into the word "Dolphin". The term mereswine (that is, "sea pig") has also historically been used.^[5]

The term 'dolphin' can be used to refer to most species in the family Delphinidae (oceanic dolphins) and the river dolphin families Iniidae (South American river dolphins), Pontoporiidae (La Plata dolphin), Lipotidae (Yangtze river dolphin) and Platanistidae (Ganges river dolphin and Indus river dolphin).^[6][7] This term has often been applied in the US, mainly in the fishing industry, to all small cetaceans (dolphins and porpoises) are considered to be porpoises,^[8] while the fish dorado is called dolphin fish.^[9] In common usage the term 'whale' is used only for the larger cetacean species,^[10] while the smaller ones with a beaked or longer nose are considered 'dolphins'.^[11] The name 'dolphin' is used casually as a synonym for bottlenose dolphin, the most common and familiar species of dolphin.^[12] There are six species of dolphins commonly thought of as whales, collectively known as blackfish: the orca, the melon-headed whale, the pygmy killer whale, the false killer whale, and the two species of pilot whales, all of which are classified under the family Delphinidae and qualify as dolphins.^[13] Although the terms 'dolphin' and 'porpoise' are sometimes used interchangeably, 'porpoise' usually refers to the Phocoenidae family, which have a shorter beak and spade-shaped teeth and differ in their behavior.^[12]

A group of dolphins is called a "school" or a "pod". Male dolphins are called "bulls", females called "cows" and young dolphins are called "calves".^[14]

 

In 1933, three hybrid dolphins beached off the Irish coast; they were hybrids between Risso's and bottlenose dolphins.^[15] This mating was later repeated in captivity, producing a hybrid calf. In captivity, a bottlenose and a rough-toothed dolphin produced hybrid offspring.^[16] A common-bottlenose hybrid lives at SeaWorld California.^[17] Other dolphin hybrids live in captivity around the world or have been reported in the wild, such as a bottlenose-Atlantic spotted hybrid.^[18] The best known hybrid is the wolphin, a false killer whale-bottlenose dolphin hybrid. The wolphin is a fertile hybrid. Two wolphins currently live at the Sea Life Park in Hawaii; the first was born in 1985 from a male false killer whale and a female bottlenose. Wolphins have also been observed in the wild.^[19]