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Are whales fish?

Whales and dolphins FAQ 

Cetaceans and sirenians are fully aquatic, whereas pinnipeds are semi-aquatic, using land for important activities like mating, breeding and moulting. Marine mammals play crucial roles in maintaining marine ecosystems, by regulating prey populations, hence it’s vastly worrying that 23% of today’s marine mammal species are threatened.


Most marine mammals reproduce slowly, so their populations are unable to withstand much human caused mortality. Removing just 1% of populations annually can be more than many species can sustain. For this reason, many nations are legislating, to protect these key populations from deliberate and accidental exploitation and killing.

No, Whales belong to a group that is called ‘marine mammals’. Just like us, they are warm-blooded, they give birth to their young alive, nurse their young with their milk, they breath using lungs and they have hair.


Another way to separate fish from whales is by the position of their tail; whales have a horizontal tail whereas fish have a vertical one.

Why do dolphins always seem happy?

When we look at a dolphin’s face, it seems as they are always smiling. However, dolphins have a significant amount of blubber under their skin, disconnecting facial muscles from their skin. This means dolphins are incapable of facial expressions.

Why are whales big?

Whales are among the largest animals that have ever lived on this planet. Even dinosaurs could not reach the same size as the blue whale. It is water buoyancy has allowed whales to attain and support their enormous sizes, but why has this happened?


Large animals generate more heat and can retain heat more efficiently. This is particularly important in the ocean where the cold water can zap away body heat up to 20 times faster than on land. 

What’s the difference between ‘whale’ and ‘dolphin’?

Marine mammals are divided into 3 groups: seals (Pinnipedia), sea-cows (Sirenia) and whales (Cetacea). This last group is again subdivided into toothed whales (Odontoceti) and baleen whales (Mysticeti).


Dolphins are a subgroup within the group of the toothed whales.  It’s mostly obvious to which group a marine mammal belongs; e.g. a striped dolphin belongs to the groups of dolphins, or the minke whale to the group of baleen whales (Mysticeti). Some exceptions however can make things a bit more complicated: the killer whale (or orca) belongs to the group of dolphins or toothed whales, and not to the group of baleen whales!

Did you know that a blue whale burns as much energy as an entire human population of 2000 individuals?

If such a large whale lived on land, over-heating would be a serious problem since air zaps away body heat more slowly than water. But since it lives in water, whales quickly lose the large amounts of heat that their bodies generate. 

How big is the biggest whale? And how small is the smallest?

The biggest whale is blue whale (Balaenoptera musculus) measuring up to 30 meters. With this length, the blue whale remains the largest animal that has ever lived on the planet. The smallest cetaceans are some species of porpoises, which measure about 1.5 meters. 

Do whales have hair?

Whales have a very hydrodynamic body structure, and therefore have lost all unnecessary protruding parts that would offer resistance to water. However, whales and dolphins are still born with hair, like all mammals.


Believe it or not they are born with facial hair, like whiskers. Early on, the calf will lose the whiskers but the hair follicle will remain. On a dolphin you can see the white spots along their rostrum. On a right whale the white patches called ‘callosities’ occur where hair follicles are present.


Some whales often appear to have moustaches, eyebrows, beards, and even side-burns.  On a humpback whale there are knobs or bumps on its head called ‘tubercles’. These tubercles are actually the hair follicle.


Marine mammals that still have hair include river dolphins and sea cows, plus of course sea lions, seals and walrus.

How fast can whales swim?

Some dolphins and porpoises have been measured at speeds of more than 40 km/h over short distances. They may go even faster when pushed by the bow wave of a boat. Some of the large baleen whales aren’t slow either. Rorquals such as blue and sei whales can reach speeds of 30-35 km/h.

Do whales sleep?

Whales and dolphins are conscious breathers. This means that they cannot go into a full deep sleep, because then they would stop breathing. They have ‘solved’ that by letting one half of their brain sleep at a time. They sleep about 8 hours a day in this fashion. REM (Rapid Eye Movement) sleep, usually associated with dreaming, has been recorded only very rarely. 

How much can whales weigh? And how do you weigh whales?

The blue whale can weigh up to 160 tons! In other words, a whale can weigh about the same as 24 elephants!


Now, how can we weigh whales? Whales in captivity will be weighed by being lifted out of the water on a sling. But what about larger whales?


In the old days of whaling, all of the various parts of a captured whale were weighed. The weights of all of the parts of the whale were added together to obtain the weight of the whole whale.


This information may still be obtained from autopsies on dead whales that have washed ashore. From looking at many measurements, scientists were able to develop a formula for each species that can estimate a whale’s weight from its length. Today, scientists simply have to estimate a whale’s length, apply the calculations, and obtain a good estimate of the whale’s weight.

Can whales hear?

Because they live in water that is often cloudy or dark, whales depend far more upon sound than sight. There are no obvious outward signs of ears, but they do have them. The ear opening is a tiny pinhole in the smooth skin surface on each side of the head. Whales hear sound in a very unusual way.


Sound vibrations are ‘picked up’ through fatty tissue in each side of the hollow lower jaw and conducted to the inner ears. As for seals, it is thought that they hear just like us.


Do whales drink sea-water?

It is believed that cetaceans and pinnipeds get adequate water from their diet, and do not have to purposely ingest sea water. However, it is very likely that they incidentally ingest sea water with their food.


Since they do not possess sweat glands, they must eliminate excess salt from the body via urine production. Whale kidneys have numerous divisions which increase surface area, allowing a greater removal of salts from the blood than human kidneys.


If a human were to drink 1 L of sea water, there would be a net water loss of approximately 350 mL. On the other hand, whales would show a net gain of 350 mL of pure water after ingesting 1 L of sea water, due to their powerful kidneys.


Thus, the kidneys of cetaceans and seals are able to produce a urine which is more concentrated than seawater; whale urine is reported to have a chloride concentration of 820 mmol/L, while seawater is approximately 535 mmol Cl/L.