Whales and dolphins
wildlife
 

Whales and dolphins


Whales are marine mammals of the order Cetacea; an order in which you will also find dolphins and porpoises. Pilot whales and so called “killer whales” (Orcas) both have the word whale in their common name but are in fact dolphins. Dolphins are found in the family Delphinidae, the largest family in the order Cetacea. There are almost 40 different species of dolphin divided into 17 different genera.   

Whale behaviour

Whales are social animals that communicate with each by producing sounds that to a human ear appear to be music. This form a communication is therefore known as whale song. Some whales, such as the sperm whale, produce clicking noises rather than musical noises. The sounds produced by a whale can be extremely loud and toothed whales are known to use echolocation that can be heard for many miles. Some whales can generate 20,000 acoustic watts of sound at 163 decibels.  

Since the whale is a mammal, not a fish, it needs to surface regularly to breathe. Unlike many other mammals whales only breathe when they decide to do so – they do not breathe automatically. Just like any other mammal the whale must sleep, but for some reason whales are often seen resting with one eye shut and one eye open. Scientists have suggested that whales might be able to let only one hemisphere of the brain fall a sleep, allowing the other one to stay alert and prevent the whale from forgetting to breathe. More research is needed before we can know if this is true or not.

Female whales give birth to a single calf which will stay with them and nurse for a long time; over a year for many species. This means that each female whale can only give rise to a comparatively limited number of calves during her reproductive years, but it also ensures a high survival rate for the offspring.

Dolphin behavior

Dolphins are social creatures that form pods consisting of up to a dozen members. Dolphins are known to form strong bonds with their friends and can be seen aiding injured or ill members of the pod, e.g. by pushing weak dolphins to the surface to prevent them from drowning. Sometimes dolphins help animals outside their own pod, including members of other species. The famous New Zealand dolphin Moko did for instance appear to guide a female Pygmy Sperm Whale and her calf out of shallow water. This type of altruism is however not shown towards one of the dolphin’s closest relative, the porpoise. Due to some type of motive that we still do not understand, dolphins sometimes kill porpoises for no apparent reason.

Just like whales, dolphins communicate with each other through sounds, typically clicks and whistles, and they also use sounds for echolocation. Dolphins are capable of teach each other things and the Indo-Pacific Bottlenose Dolphin will for instance instruct their offspring on how to use certain tools. The dolphins seek out sponges growing on reefs, break them off, and use them to protect their sensitive snouts when foraging for food.    

Places with plenty of food can attract numerous dolphin pods which may join forces for a while, forming a so called superpod. Superpods comprising over one thousand dolphins have been spotted in regions temporarily rich in food.

Whale & Dolphin Articles:

Beluga Whale
Beluga Whale Facts
Blue Whale
Blue Whale Facts
Bottlenose Dolphin
Bottlenose Dolphin Facts
Humpback Whale
Humpback Whale Facts
Sperm Whale
Pygme Sperm Whale


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