Blue Whale
The blue whale (Balaenoptera musculus) is the largest animal known to have ever existed. These marine mammals belong to the baleen whale suborder, Mysticeti. Blue whales are found in oceans all over the world, and they are known for their immense size, reaching lengths of up to 100 feet and weights of up to 200 tons.
Physical Characteristics
Blue whales have a long, streamlined body that is predominantly blue-gray in color, with lighter underbellies. Their skin often appears mottled due to the presence of diatoms, which are tiny organisms that cling to their skin. The head of a blue whale is flat and U-shaped, and it has a prominent ridge running from the blowhole to the top of the upper lip. Blue whales have between 55 and 68 ventral pleats running from the lower jaw to the navel, which expand when feeding.
Habitat
Blue whales are found in all the world's oceans, except the Arctic. They prefer deep ocean waters over coastal areas. During the summer, they are typically found in polar waters where they feed on krill. In the winter, they migrate to more temperate and tropical waters to breed and give birth. Notable populations of blue whales can be found in the North Atlantic, North Pacific, and the Southern Ocean.
Diet
Blue whales are filter feeders, primarily consuming krill, which are small shrimp-like crustaceans. They use their baleen plates to filter these tiny organisms from the water. During feeding, a blue whale can consume up to 4 tons of krill per day. They feed by taking in a large mouthful of water and then pushing the water out through their baleen plates, trapping the krill inside.
Behavior
Blue whales are generally solitary animals, although they can be found in pairs or small groups. They are known for their deep, resonant calls, which can be heard over vast distances underwater. These calls are believed to play a role in communication and navigation. Blue whales are also known for their impressive acrobatics, including breaching and tail slapping.
Reproduction
Blue whales reach sexual maturity at around 10 years of age. The gestation period for a blue whale is about 10 to 12 months, and females typically give birth to a single calf. Calves are born in warm, tropical waters and are nursed for about 6 to 7 months before they are weaned. During this time, the calf can gain up to 200 pounds per day.
Conservation Status
The blue whale is currently classified as Endangered by the International Union for Conservation of Nature (IUCN). The primary threat to blue whales has historically been whaling, which drastically reduced their populations in the 20th century. Although commercial whaling has been largely banned, blue whales still face threats from ship strikes, entanglement in fishing gear, and the impacts of climate change on their food supply.