Chapter 2: Modern-Day Whales

In Chapter 2, you will learn about the physical characteristics and behaviors of whales which live in seas and oceans.

There are currently about 90 different species of whales on earth, all of which have bodies specialized to live in water all through their lives. Their ear bones, for example, are separated from the skull, which enables the whale to hear well in water. The bones of whales are low in density and filled with fatty marrow that facilitates buoyancy, since the whale does not have a swim bladder as fish do. Whales rest half of their brains while sleeping; baby whales are usually born tail first to minimize the risk of drowning. The footage of a whale giving birth can be viewed in the viewing section.

There are 14 species of baleen whale species including ‘small’ Pygmy right whales, which are about 6 meters in length, and the largest whale of all, the Blue whale, which can reach 30 meters long. Females are bigger than males, which is rare among mammals. Many species of baleen whale migrate annually from cold-water feeding grounds near the poles in summer to warm tropical waters for breeding, where the adults do not eat. Because of this half-yearly migration pattern, a whale’s age can be estimated by examining its earwax. When the whale is feeding, a layer of light-colored, fat-rich wax accumulates in its ears, whereas when it is not feeding, it is dark-colored. Whale calves stay with their mothers for about a year and some species are believed to live for 150 or even 200 years.

76 species of toothed whales are known to the world. Although toothed whales do not undergo long-distance migrations as baleen whales do, some species dive to depths of nearly 3,000 meters to feed. The majority of toothed whales are smaller than 4 meters in length, but some species, such as Sperm whales, can grow up to 16 meters. Another distinguishing characteristic of toothed whales is that many of them are sexually dimorphic, showing differences in appearance between males and females of the same species in size and shape. In Narwhals, for example, only males have a tusk that protrudes from their left jaw. Toothed whales in general are highly social animals, moving about in social groups known as pods, whose structure is fluid. Some stay in the natal pod for their entire lives while others leave it when they grow up. The lifespan of toothed whales varies; Common bottlenose dolphins and Striped dolphins can live for 40 or 50 years and the record for the oldest toothed whale is an 83-year-old Baird’s beaked whale.

Whales play important roles in the complex web of relationships with other sea creatures in the oceanic environment. On the one hand, they are ferocious predators feeding upon krill, fish and squids, but on the other, they are susceptible to parasites or eaten by Cookiecutter sharks, for example. Even when a whale dies, it contributes to the ecosystem of the deep sea where the body has sunk. There are cetacean on cetacean interactions as well, such as when Orcas attack and eat other whales. Humans are also in a web of relationships with whales. In some cases, we are directly and actively involved with whales through eating them, keeping them in aquariums or going on whale-watching tours, whereas we sometimes have a huge impact upon them without realizing it, for instance, when waste is dumped in the ocean.

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