ALL ABOUT WHALES AND DOLPHINS

 

WELCOME TO THE WORLD OF WHALES AND DOLPHINS

 

How many species of whale and dolphin are there? Where have they come from? How do they socialise and behave? Find out the answers to these questions and more.

VARIETY

‘Cetaceans’ is the collective name for all whales, dolphins and porpoises who between them form a single group, known as an order. It's a huge group, though, comprising around 90 species, so let's break it down.

To begin with, cetaceans can be divided into two categories; baleen whales, and toothed whales. Baleen plates, or whalebone, are comb-like bristles that hang from the upper jaw of most large whales and allow them to filter-feed. When whales open their mouths, water and prey, such as krill or small fish upon which they feed, pour in. The water floods back out but the baleen filters out the prey for the whale to then swallow. Blue,humpback, gray and right whales are all included in this group.

The vast majority of whales and dolphins, however, belong in the toothed category, and they feed on prey in a similar manner to most carnivores. These include the beaked whales, the dolphins and the porpoises. Thesperm whale also sits here (the only large whale in this category) as do thebeluga and narwhal.

The dolphins form the largest group, and (rather confusingly) include theorca, or killer whale, as well as the pilot whales. Marine dolphins can be found all around the world, varying in size and colouration, but rarely coming closer inland than bays or estuaries. There are a few species offreshwater dolphins, however, which are found in some of the largest of the world's rivers. Sadly, one of them, the Yangtze River dolphin, was declared functionally extinct in 2007.

Beaked whales are the least known of all cetaceans, as they principally lead their lives in deep waters. There are at least 20 different species in all.

The porpoises are distinguished from dolphins by their stubbier beaks and flatter teeth.

With such a wide range of skills, feeding habits, behavioural patterns and more, there's a whale, dolphin or porpoise to suit virtually every aquatic environment on the planet.

SOCIETY

To give the well-known phrase a twist, no whale or dolphin is an island. These marine mammals are in fact highly social, sometimes forming superpods of 1,000 individuals or more.

These wide-ranging communities, or societies, are not just for company either. They are built upon complex structures and levels of interdependence that can only be forged from the strongest of social bonds. In some dolphin societies, for example, groups will stay with injured or sick individuals, even physically supporting them to the surface if necessary so that they can breathe. 

Roles are very important in whale and dolphin societies. Older individuals often act as surrogate parents or as guardians of crèches, so that responsibilities can be shared around a group. Feeding systems, migratory patterns, group play and much more are all based on these strong social systems.

Communication is vital in all these circumstances, and whales and dolphins have developed some of the richest languages known. Clicks, grunts, whistles, calls, songs and more of extraordinary variety provide them with extensive vocabularies that cover all situations. Scientists are still trying to unravel the complexities of these languages, and it will be a long time before we are even close to understanding the full range.

One thing is certain: it is only within the heart of their communities that whales and dolphins can lead their lives to the full.

BACK TO THE WATER

There are many mammals that spend time in the water. Seals, sea lions, walruses, water voles, the platypus and many more are capable of prolonged periods swimming above or below the surface, but all of them come onto the land. What makes whales, dolphins and porpoises different to all of these is that they live entirely in the water.