A Whale of a Tale

Tuesday, February 18, 2025

A Whale of a Tale

Today’s special animal friend is the largest animal known to have existed on earth, ever: the blue whale, Balaenoptera musculus. There is a blue whale skeleton at the North Carolina Natural Science Museum, and it is astounding. Its jaws could easily swallow my van, but the world's largest-ever animal eats only small crustaceans commonly called “krill,” miniscule fish, and oceanic debris no more than 1 mm in size. As the whale dives, its enormous jaws open and its mouth and throat tissue expand to engulf a volume of water that may be greater than the normal size of the whale. The whale then forces the water out through the sieve-like baleen plates inside its mouth, trapping the tiny food bits inside. Scientists are not sure how blue whales handle the water pressures without their jaws breaking. Both the bone composition and the shape and alignment of the jaws are being studied.

The maximum confirmed length of a blue whale was 98 feet. Their weight can reach 438,720 lbs. (or 199 tonnes). For perspective, that's about 1/3 more than the weight of a freight car full of iron ore. Females are slightly longer and heavier than males. A full-grown blue whale’s heart is as big as a compact car. The body is slender, compared to the length, and slightly tapered toward the tail. They are bluish to grayish on the top and lighter underneath.

Once abundant throughout the world’s oceans, blue whales were hunted nearly to extinction in the 18^th and 19^th centuries. Since the ban on whale hunting, populations have recovered, and the blue whale is now considered endangered – a step up from “critically endangered” - by IUCN. Although blue whales move around the ocean, they do not show a seasonal migration pattern like some other species. They have no social organization other than mother-calf bonds. Mating and birth have not been well studied. Females give birth every two to three years. A calf can be over 20 feet long at birth, and weaning takes place at six to eight months, though the calf often remains with its mother for a longer period.

Blue whales can live more than seventy years. Scientists determine the age of a blue whale by looking at its ear wax. Seriously. Long, multilayered plugs of wax form in their ears. For each year, there will be a lighter and a darker layer based on seasonal food supplies. Count one year for each pair of layers, and you know how old the whale is. You’d think this would affect their hearing, but who knows. The blue whale is the loudest animal on earth. Their calls can reach 188 decibels; a jet engine is around 140. The low frequency “whistle” can be heard for hundreds of miles through the ocean and is believed to help whales locate mates.

Orcas (killer whales) are the only natural predator of blue whales. Ship collisions are another threat, affecting maybe 20 whales per year. Large-scale habitat issues, such as water temperature, krill populations, pollution, and oceanic noise are other factors affecting blue whale populations. The global population is estimated to be 10,000 – 25,000 individuals, which is a very broad estimate. It is surprising how little detailed information is available about such a large animal!