Whales - Facts | Anatomy

Anatomy

The bodies of whales are streamlined, with a large head tapering down into a tail. This shape is referred to as 'fusiform' and allows for ease of movement through the water. The front flippers are oar-shaped, and the large tail (or fluke) moves up and down (as opposed to side-to-side) to propel the sometimes massive bodies through the waters. Some whales, such as the Sperm Whale, have rudimentary hind limbs as part of the whale anatomy. A few rare species even have feet with digits at the end of these limbs. The dorsal fin (present in almost all species of whale) is situated on the back, although proximity to head and tail differs from species to species.

Whales are well-known for the layer of blubber or fat, which lies just beneath the surface of the thick, leathery skin. Whales are warm-blooded mammals and this layer of blubber keeps them warm, even in the iciest Arctic waters. Blubber also provides much-needed energy reserves for the months when the whales are particularly active, or need extra energy for calving. Unfortunately, blubber has also led to the deaths of many whales, as it is used to make candles, soaps, etc.

The bone structure of the whale is designed for ease of swimming and lithe movement. Most whales do not have separate vertebrae in the neck. They are fused together to ensure that the whales remain as stable as possible, as their bodies can reach enormous dimensions. This does limit their flexibility.

The blowhole, through which whales breathe, is located on the very top of the head. This allows them to breathe while keeping their bodies submerged. Some interesting whale information is that only toothed whales have one blowhole. Baleen whales have two blowholes, situated next to one another. When the muscle of the blowhole is relaxed, it closes the hole to prevent water from entering the lungs when the whale is fully submerged, which would cause the whale to drown. When they need to breathe in air, they rise to the surface and expel the air in their lungs in one explosive surge (often causing the surrounding water to blow as well and, therefore, appearing as if they are blowing out water). They inhale a large breath through their blowhole, which leads down their trachea and into their ample lungs. Some whales can hold this air in for up to two hours before rising for a fresh breath. When exhaling, each species’ blowhole is of a different shape, differentiating them from other types of whale.

Toothed whales, such as the Sperm- and Pilot Whale, have a row of cementum-covered teeth, which they use to chew through squid, crustaceans and small fish. This cementum even covers the exposed part of the tooth; unlike humans who have an enamel coating. Baleen whales have plates that act like sieves, sifting valuable food particles out of the water. Examples of baleen whales include the Blue- and Humpback Whale. Baleen whales are larger than their toothed counterparts. The smallest baleen whale is the Pygmy Right Whale, which averages a length of 6.5m. The largest animal on the earth is the Blue Whale, which measures an astounding 30.5m. The largest toothed whale, the Sperm Whale, measures only about 18m at adulthood.

The ear of the whale is particularly interesting as it has been specially designed for their underwater environment. Human have a "middle ear", which compensates for the difference in the impedance (resistance to sound waves) within the ear, and that of the impedance of the air outside. Whales, however, do not need such a converter as the water around them and the fluid within their ears share a similar pressure. In their case, whales receive sound waves through their lower jaw, where the waves pass through a low-pressure cavity.

The intuitive design of the whale anatomy is humbling and inspires awe, increasing as we gradually learn more about these mysterious giants.