Blue Whales – Largest Living Mammals on the Earth

Blue whales or Balaenoptera Musculus are the largest mammals living on this planet, Earth, as known by most of you. Earlier it was also known as “Sibbald’s Rorqual” and the “Great Northern Rorqual”. It belongs to the Rorqual clan which also includes the Humpback whale, Fin whale, and the Minke whale.

Anatomy

Blue whales, in correspondence with their size, have never been able to weigh whole. The weight we have is just approx as the gigantic animal has to be cut into manageable pieces before being weighed which results in loss of blood and other body fluids, giving us just an estimate of the weight which comes to be 170-180 metric tons. This huge animals tongue itself is heavier than the African Elephant!

In shape, it is much more stocky and stretched with a tapering body as compared to other whales. It also has an opening in the dorsal side known as the blowhole. This blowhole expels extra water taken in during the process of feeding. Its U shaped head could be followed by a ridge till the blow head. The females are found to be larger than males here. Its arteries are as gigantic, like the animal, and the aorta can actually hold a whole human body!

Their dorsal fins are small, about 8-10 cms. The flippers grow up to 4 meters.

Respiration

Respiration is an interesting process in these mammals. We know of fishes to respire through gills but here I stress the word mammals and remind you that mammals respire through lungs. So how do these underwater mammals respire? Well they do use lungs and take in oxygen from the air. For this, they have to keep surfacing and so can be spotted at prominent places above the water level.

Feeding

These large mammals survive largely on krill. Krill is a small, invertebrate marine animal found at about 100 meters of depth of the waters. Lined along the animal’s upper jaw are baleen plates. When the creature takes in food, the baleen plates retain the krill and let the water be expelled out the blow hole.

These animals need enough energy to maintain their 170 metric ton body and for that they depend on their intake of krill. An adult can consume up to 40 millions of krill in a day!

Reproduction

They reproduce during the autumn and winter months and the gestation period involves a whole year. The calf as long as 7 meters weighs up to 2.5 metric tons. Requiring around 400 liters of milk daily, they grow 1.5 inch daily. They can reproduce typically only after three to four years.

Vocalization

A blue whale can make sounds up to 177 – 180 decibels which is out of the range of 20Hz to 20 kHz, the range of sound human ear can hear, making it impossible for the humans to catch. However, a group of blue whales can make a sound ranging from 10Hz to 14Hz. This has sometimes been heard by the people present on the occasion.

Current situation of blue whales

Keeping in view the size of these creatures, it was very difficult to kill them in the early days. It was not until a special harpoon was invented that killing of this animal was plausible. But after their poaching started, it continued on a mindless rate. Today, according to the 2002 census only 5000-12000 of these are known to be living.

Blue whales are now marked as an endangered species. Steps are being taken to conserve them but the effect is not so massive.

We need to create awareness of the importance of this magnificent creature and save them from becoming a relic of the past!