They are the largest creatures to ever live on Earth. The biggest, weighs in excess of 180 tonnes, twice as heavy as the largest dinosaur. Perhaps what is most amazing is that these enormous creatures are still with us, still roaming the seas.
But there is much more to whales than just their size. And as we discover more and more about our mammalian cousins, it is becoming increasingly clear that these are highly intelligent creatures with a lot to teach us.
The Original Hippo?
Whales were originally land animals, most closely related to the hippopotamus. For whatever reason, the ancestors of whales decided to return into the sea. The proof of this is found in vestigial remains of hind limbs which are buried deep within the body of the whale. It is also worth noting that their stomachs are multi-chambered belying their ungulate origins.
Pakicetus is thought to be the ancestor of all whales. A small dog-sized hunting animal, pakicetus was very different from modern-day whales.
Originally whales would have had fur but gradually over time they developed blubber. Blubber is a much better insulator than fur and allowed the whales to dive into deeper water without the risk of hypothermia.
Toothed And Baleen Types
There are two kinds of whales. The toothed whales which include the Sperm whale, dolphins, including the Killer Whale and the extremely strange, Narwhal. The other variety is the baleen whale which are filter feeders. The Fin whale, Right Whale and Humpback whale are baleen cetaceans.
With the notable exception of the Sperm whale, toothed whales are generally a lot smaller than baleen whales. They use echolocation to hunt their food and have much larger brains than their baleen counterparts.
Baleen whales do not have teeth. Instead they have hairs which filter out the sea water and retain the fish. This hairy filter, or baleen, can be up to three metres (ten feet) in length and weigh up to 90 kilograms (200 lbs).
Baleen whales eat as much fish as possible while maximising their efficiency. They do this by swallowing as much as fish as their massive mouths allow.
Baleen whales, like the fin whale, have another trick up their sleeve which allows them to catch fish in massive quantities. This adaptation is found in their jaws. Their mouths open through dis-articulating jaws taking in as much food as feasible.
The whales hyoid bone is heavily involved in their vocalisation process. The larynx is incredibly elastic, ballooning out it forces air through.
Both baleen and toothed whales can be heard for hundreds of miles underwater.
Communication and Locomotion
Both dolphins and whales move very differently from fish. Whereas fish propel themselves with a side to side motion, whales and dolphins gain trust by moving their body along a vertical plane.
The hyoid is a critical bone for locomotion. According to comparative anatomist, Joy Reidenberg, the whale’s ability to move starts with its throat and the hyoid bone.
A Colossal Digestive System
The digestive system of whales are massive. The intestines of whales are thought to be five to six times the total length of their body. Therefore, a fin whale of 25 metres (80 feet) in length would have an intestinal tract of between 125 and 150 metres (400 and 500 feet).
Due to their aquatic environments, whale faeces contains a high amount of water in comparison to a land mammal. This helps it to get rid of waste more effectively.
Adapted For The Great Deep
The alien world of the aquatic is very different from the environment that we inhabit on a daily basis. Down in the deep waters of the Earth’s oceans, pressures are incredible, enough to crush all but the most specialised of creatures. To cope with overwhelming forces and the long duration of many of its dives, the whale has unusual adaptations.
The whales heart, which can weigh over one tonne, pumps at a very slow rate of two to three beats per minute when underwater. The lungs can take in over 2,000 litres in one breath.
With the huge pressures of the deep water sensory parts must be adapted. The eye of a whale is very strong and does not compress despite the huge forces. Whales ears, which are critical for both communication and echolocation are attached to their skulls and are not external like many land-based mammals.
A Difference Of Size
One thing that immediately strikes us about whales is their appearance. Whales have reached the size that they are because of the environment they live in. In a weightless world, whales are free to grow to massive sizes.
- Whales can be as small as 2.5 metres in length (dwarf sperm whale) and as long as 30 metres (blue whale).
- They can weigh as little as 250 kilogrammes (550 lbs) and as much as 180 tonnes.
- Bowhead whales can live to be over 200 years.
- Whales are found throughout our oceans.
You might like to check out Yellow Magpie’s Dolphin: Our Love Affair With Our Favourite Cetacean, Beluga Whale: The White Melon-headed Creature Of The Cold and Gray Whale: The Gigantic Voyagers Of The Oceans.
Inside Nature’s Giants is a well-shot Channel 4 documentary. From September 2011 a book will be available covering the animals shown in the series.
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