The largest land animal is the elephant, while the largest ocean animal is the whale. Perhaps this is because the ocean is much larger than the land, making whales many times larger than elephants—a phenomenon that could be called the scale effect. Therefore, whales are currently the largest animals on Earth.
There are over 90 species of animals belonging to the order Cetacea on Earth, making it a truly vast family. However, what we call whales are not actually fish, but rather fish-shaped vertebrates belonging to the class Mammalia and the order Cetacea. More than 50 million years ago, the ancestors of modern whales left the land and entered the vast ocean, and over a long period of time, they gradually evolved into their present form, spreading throughout the world's oceans.
Modern whales have highly streamlined bodies, which facilitates swimming and reduces water resistance. Therefore, whether the sea is calm or stormy, they remain composed, as if strolling leisurely. Whales have hairless bodies, and their smooth skin forms a slippery surface, which also reduces water resistance during propulsion. Their forelimbs have degenerated into flippers, their hind limbs are reduced, and their tails are horizontally arranged (horizontal tail fin), which is a unique characteristic of these marine vertebrates.
Another distinctive feature of whales is their external blowhole, located on the top of their head and back, forming a blowhole. On the shimmering ocean, tall, feather-like columns of water and spray can often be seen, resembling geysers—a truly spectacular sight. The whale's internal blowhole opens into its throat, allowing it to safely swallow food underwater without choking. Its lungs have great elasticity and capacity, enabling it to inhale large amounts of air at once, allowing whales to remain underwater for extended periods, and some can even dive to great depths.
Whales are warm-blooded animals, maintaining a body temperature of around 37°C, similar to human body temperature. However, seawater is cold, especially in the Arctic, where temperatures often drop below zero. Furthermore, water absorbs heat much faster than air, so whales have a thick, spongy skin layer and a thick layer of blubber underneath as insulation to minimize heat loss. In addition, because water resistance is much greater than air resistance, whales require significantly more energy and stamina to move. Of course, every disadvantage has its advantage; the abundance of food and fewer competitors in the ocean make it easier to find food. And perhaps more importantly, while seawater offers great resistance, it also provides great buoyancy. A whale, tens of meters long and weighing over 100 tons, simply could not survive on land. Forget foraging; even moving would be extremely difficult. Therefore, whales offer obese people a way to live without dieting: return to the water!
