The largest animal that has ever lived on earth, and one of the loudest. Here is what is known about the blue whale, and where it sits alongside the humpbacks we watch in Jervis Bay.
The blue whale (Balaenoptera musculus) is the largest animal known to have lived on earth, bigger than any dinosaur. A blue whale's tongue alone can weigh about as much as an elephant, and its heart is roughly the size of a small car.
It is also one of the loudest animals in existence. Blue whales call at very low frequencies, below the range of human hearing, and those calls carry for enormous distances through deep water.
Despite the name, a blue whale is not really blue. Out of the water it is a mottled blue-grey. Under the surface, the way sunlight passes through seawater makes it look a far deeper blue than it actually is.
For something so large it is built for travel. The body is long and slim rather than bulky, and from above a blue whale looks a little like a submarine with flippers and a tail.
Blue whales are found in every ocean except the Arctic. They spend the feeding season in cold, productive water, then move towards warmer waters to breed and calve, and they cover thousands of kilometres doing it.
They largely fast on the way, living off the reserves built up during the feeding season, which is the same pattern that drives the annual migration of the humpbacks past the New South Wales coast.
Australia does have blue whales, but they are almost all pygmy blue whales and they are almost all on the other side of the country. The reliable places are the Perth Canyon in Western Australia and the Bonney Upwelling off the Victorian and South Australian coast, where cold, nutrient-rich water rises and the krill come with it.
On the east coast a blue whale is a once-in-many-years event. Research out of Macquarie University found only six verified sightings off Sydney across eighteen years, and the species is listed as endangered in New South Wales. So it is a genuine possibility rather than something anyone can offer you: the whales on our whale watching cruise are humpbacks, on the Humpback Highway, from mid-May to mid-November.
Almost entirely krill. A feeding blue whale lunges through a swarm with its mouth open, takes in an enormous volume of water, then pushes the water back out through its baleen plates and swallows what is left behind. It is the same filter feeding the other baleen whales and the fur seals around Jervis Bay rely on, at a far larger scale.
Because they are feeding on one of the smallest animals in the ocean, blue whales have to eat an extraordinary amount of it, and they do most of that eating in a short, intense season.
Yes. Industrial whaling in the twentieth century reduced blue whales to a tiny fraction of their original numbers, and they are listed as endangered on the IUCN Red List. They are protected in Australian waters.
The picture is not uniformly bleak. Blue whales in the eastern North Pacific have recovered to close to their historic size, and Antarctic blue whales are increasing again after being reduced to a few hundred animals. But the Antarctic subspecies, the one relevant to this half of the world, is still separately listed as critically endangered and remains at a tiny fraction of what it was before whaling.
For several populations the numbers are simply not well known, which is its own kind of answer.
Humpbacks pass the bay from mid-May to mid-November. Watch them from the water, alongside the sea cliffs and caves.
