Whales have long been considered the most majestic and extraordinary of all sea creatures. As the largest animals on earth, a blue whale was recorded being 30 metres (98 feet) long and weighing a huge 180 tonnes. Yet these giant beasts are seen by humans as fascinating, peaceful sea creatures, with many boat tours operating daily to try and catch a glimpse of these majestic beasts.
The Evolution of the Whale
All whales, that belong to the cetacean family along with dolphins and porpoises, are originally descendants of land dwelling mammals. It has been found that whales are related to the Indohyus, an extinct semi-aquatic deer-like animal, that lived around 54 million years ago. It is believed that these primitive form of whale cetaceans took to the ocean roughly 50 million years ago, evolving to become completely aquatic around 5 to 10 million years later.
The evolution process would have included changing the cetacean to suit the marine environment, including streamlining the body, changing the breathing system, and eventually removing unused libs, changing them into flippers and tails.
A whale’s blowhole is located on top of the whales head, and acts like a value that blasts air out when the animal reaches the surface of the water to breath. As the whale breathes at the surface, it blasts an oily substance out of its blowhole. If you ever see a whale, you may assume that it is water that is coming up from its blowhole, but in fact that is not true. If a whale actually had water in its lungs it would drown. Instead the liquid in the whale contains nitrogen that the whale’s lungs have removed from air. This nitrogen helps the whale to dive to tremendously deep depths and come to the surface quickly without the need to equalise from the water pressure. The spray from the blowhole of a whale can be blasted as high as 12 metres (40 feet).
Diving to Great Depths
Because of the intense pressure of the water, if a human tried to swim just a couple of hundred metres beneath the surface of the water, their rib cage would be under so much pressure that it would be crushed. However a sperm whale can dive to much greater depths without causing any injury to itself. It achieves this by collapsing its own rib cage, allowing its lungs to fold up and compress the air in its body to a quarter of the volume it was on the surface of the water. Without this ability to deflate its lungs, the whale’s blood vessels would burst.Credit: Wikimedia
Hunting and Eating
Most of the bigger whale species, like the blue whale, don’t actually have any teeth. Instead they have baleen, which are triangular shaped plates that hang down from the roof of their mouths. As they swim, they open their mouths and the baleen works as a filter, straining and catching the krill and plankton in the water. The whale then has to get rid of all the water, so the whale’s huge tongue pushes the water back out the month through the baleen, again acting as a filter to catch any krill or plankton missed the first time around. The whale then closes its mouth and any krill or plankton left on the baleen is swept up by the tongue and swallowed.
When it comes to sperm whales, they hunt for their food, with their favourite meal being the giant squid. Because sperm whales can hold their breath for up to an hour, they are prolific at deep-sea diving. Diving to depths of 2000 metres or more, the largest of the toothed whales begins their hunt for food.
Sperm whales use echo-location, which is a type of sonar that using clicking sounds to track the location of giant squid. The whale will emit a distinctive clicking sound, which will bounce back off potential prey, alerting the whale to its presence. Sperm whales produce ambergris, a dark waxy substance that is produced in the lower intestines. Some scientists think that it might be used to protect the sperm whale from giant squid stings when they are hunting.
When defining whales, males are called ‘bulls’, females are ‘cows’ and newborn whales are called ‘calves’. There is no monogamy amongst whales, as a female will have several mates during each mating season.
When a female gives birth, it is usually just a single calf. The calf is born tail-first to minimize the risk of the newborn drowning during the delivery process. A mother will feed their young by squirting milking into the mouth of the newborn calf. This milk substance is extremely rich in fat and has the consistency of toothpaste. In most whale species, the mother will nurse the newborn for over a year, forging a strong bond with the calf. A whale will reach sexual maturing between the ages of seven and ten years old.
More Whale Facts
- The sound of a blue whale can be as loud as a rocket taking off, roughly 190 decibels.
- A whale’s song can travel hundred, even thousands of kilometres.
- Blue whales can live to be 110, but their average life span is around 30-90 years.
- A whale’s tail fin is called a fluke and on the largest whales it is as wide as the wing on a small aeroplane. It is specifically designed to push the whale vertically through the water.
- Whales are conscious while they are asleep, as they can’t afford to become unconscious as they may drown. It is believed that one side of the whale’s brain sleeps at a time, so they can rest, but are never completely unconscious.
- Whales don't hear through their inner ear like humans do. Instead the recieve the sound through their throat, where it then passes through a fat-filled cavity and into the inner ear. The ear is isolated from the whale's skull by air-filled sinus pockets, as this allows for better hearing underwater in all directions.