The blue whale can grow to be 80 – 100 feet long (60 – 80 ft. on average) and weigh more than 150 tons when it is fully matured. Although blue whales can grow to be massive marine animals, they have slender, streamlined bodies that easily move through the ocean with very little water resistance.
Blue whales also have an aerodynamically flat, U-shaped head, which helps them reach relatively high speeds of up to 30 miles per hour for short periods of time when they feel threatened or alarmed. However, most blue whales generally keep a speed of between 3 – 12 miles per hour depending on their activities such as foraging for food, resting, or traveling to different locations.
At birth, a baby blue whale can measure at around 25 feet and grow very quickly over the next few years. During the first year of birth, a baby blue whale can gain as much as 200 pounds per day and consume up to 100 gallons of milk every 24 hours.
In addition to being the largest living animal in existence, blue whales are also known to have some of the largest organs of any known animal. A blue whale’s tongue, for instance, can weigh as much as 3 tons, and its heart can grow to weigh more than 1,300 pounds!
However, despite being the largest living animal in the world, a blue whales diet consists largely of krill (a small aquatic life-form that measures between 1 centimeter & 6 inches in size depending on the krill’s species); however, in some cases, blue whales may consume fish and other small aquatic sea life while consuming krill.
Another amazing fact about blue whales is that in addition to having a relatively small diet, these whales will also forgo eating for as long as 4 months during migration periods by living off the stored fat they’ve acquired during feeding season. Even with their diet and long food-less migration periods, blue whales still manage to be impressively large.
Regarding why some of the largest living animals are whales, it makes perfect sense that the largest living animals would inhibit the sea because factors such as body size and food supply play a big role in an animal’s ability to survive.
Land animals have to be able to maneuver on land. Hence, their physical size is significant for them to move around without worrying about getting stuck or bumping into objects such as trees, rocks, and other animals. Food scarcity would also prevent land animals from growing beyond a certain size.
The amount of food a large whale consumes daily would be nearly impossible to find in most environments on earth, with, of course, the exception of the ocean.
If an animal as large as a whale lived on this earth, it would require a tremendous amount of food and energy to support the muscles needed to move around on land.
In fact, land animals would need additional muscles to support gravity, which is unnecessary in the ocean, so they would likely consume even more food than a blue whale would need to survive.
On an even smaller and lighter scale, flying species such as birds need to lift their bodies off the ground for extended periods of time and maintain flight, so most flying species have relatively light bodies and wings required to maintain flight.
For whales and other marine mammals, water provides buoyancy, which allows them to grow huge without strong muscular limbs or a skeletal system needed to support the additional weight and protect their organs, which would be required if they lived on land. In addition to buoyancy, water also provides whales with an abundant food supply, which would be nearly impossible to find on land.