A whale is a marine mammal – a warm-blooded air-breathing animal that gives birth to live young and is part of the cetacean family. There are over 80 species of cetaceans, which is the collective term for whales, dolphins and porpoises.
Cetaceans can be divided into two main groups; baleen whales, characterised by their baleen plates used for filter feeding, which have two blow holes, and toothed whales which have teeth and a single blowhole. The so called ‘great whales’ consist of 12 species of baleen whale and the largest of the toothed whale family – the sperm whale.
Although their ancestors are believed to be land-living animals, whales have been evolving in our oceans for 50 million years and are perfectly adapted to an aquatic existence.
Their sheer size and enigmatic lives make them amongst the most captivating of all mammals.
Due to the inherent difficulties of observing the great whales in their vast and deep ocean environment, our understanding of the lives of whales is extremely limited. Much of the research on whales focuses on estimating their numbers and migratory patterns with fewer studies aimed at investigating the complexities of their lives beneath the waves. However, existing projects to film and document whales underwater offer a fascinating insight into their behaviours, social groupings and individual personalities.
Whales show a wide range of different behaviours, social organisations and communication methods which differ greatly between species.
Many whales, particularly juveniles, are inquisitive and playful and can frequently be observed interacting with boats and divers as well as with one another – perhaps one of the reasons why whale watching is a popular and growing activity all over the world.
The acrobatic displays of humpback whales, including spectacular breaches out of the water, are particularly captivating to watch. However many species show behaviours such as fin and tail slapping which are thought to have a range of functions, including play, signalling position to other whales and signs of excitement or surprise.
Whales can be curious animals and species such as humpback and right whales are known for their tendency to approach boats. Many cetacean species can be observed ‘spy hopping’ – hanging vertically with the head above the water – which is also often attributed to curiosity.
Whales are known to communicate with each other over thousands of miles of ocean; their songs thought to form an important part of their social systems and communities.
Toothed whales such as orcas, sperm and pilot whales are more frequently observed in groups or ‘pods’ than baleen whales. In some species these groups are long-term and involve close bonds between individuals and even cooperative hunting.
Depending on species, calves can remain with their mothers for up to 18 months. The close bond between mother and calf is clear; females are protective of their young, actively steering them away from threats and defending them against predators.
Resting calves can often be seen anchored under their mother, to maintain contact in the vast and potentially dangerous ocean environment.
Whales reach sexual maturity at varying ages depending on species – humpback whales mature by four years of age but bowheads are not mature until 15 to 20 years old. It is not known how long all the different species may live but many of the larger species, such as blue and fin whales, are known to have a lifespan of at least 70 years.
Male humpback whales are known for their extremely elaborate courtship songs – they will repeat unique phrases of sounds in songs lasting up to 30 minutes which they may then repeat for several hours. These songs are unique within populations and evolve and lengthen over time, demonstrating cultural learning. The complex vocalisations are thought to be used to attract females and to establish dominancy in groups.
Male humpbacks are also known for their competitiveness for mating opportunities. Males inflate their ventral pouches with air, giving an illusion of greater size to warn off competing males and blow long streams of bubbles into the water to form a curtain between the female and rival males, intimidating other males in the group and reducing their chances of getting close to her.
Gestation periods vary significantly between species but tend to be long; most baleen whales are pregnant for close to a year and sperm whales are pregnant for 16 months. Although this may seem a long time, the huge size of whales means that foetuses must fit a great deal of growth into this time period – the foetal growth rate of whales is actually 20 times that of primates.
Many whales migrate over thousands of miles of open ocean, following the same route year on year. How they do this is not yet fully understood, but scientists have shown that blue whales produce extremely low frequency sounds that may be used in navigation.
Humpback whales undertake the longest migration of any mammal. Each year they journey from their cold water feeding grounds up into warmer tropical waters to breed and give birth. This journey can be as long as 10,000 miles (16,000 km).
Whalewatch believes that the long term study of whales is necessary to promote greater understanding of these unique and fascinating animals and in order for us both to enjoy and protect them in their changing marine environment. Whalewatch believes that the International Whaling Commission (IWC) should devote more of its time, resources and expertise into researching whale behaviour, ecology and biology in order to fulfil its mandate for cetacean protection.