Cetacean Society International

Working for whales, dolphins and porpoises worldwide

CSI Photo Gallery

Blue Whales

(Balaenoptera musculus)

This blue whale's blow is over 10 meters high, a roaring rush of air and mist that can be heard and seen for miles, and always awes whale watchers. But it's just a normal breath for the world's largest creature. Everything about blue whales is enormous, except their numbers. Perhaps 200,000 were alive before modern whaling, but today only a few hundred survive in the North Atlantic, and perhaps 5,000 roam the North Pacific and Southern Oceans. In 1931 over 29,000 were killed in one season, and pirate whalers still kill them whenever possible.
Because of her size, perhaps 80 feet long, the foot-tall but tiny dorsal fin of this whale's will usually appear well after her head has gone under. This blue whale is very light colored, but others are dark. Each one also has different marks and scars, enabling scientists to identify individuals. Skin and blubber samples allow us to learn much more, including their health. Radio and satellite tags show us how far and fast blue whales wander, traveling thousands of miles in search of other whales and food. As we learn more about them we find that they behave individually too.
With a mass of almost 150 tons, this whale moves with grace, power and speed hour after hour, even when resting. She must find and eat perhaps four tons a day of shrimp-sized euphausiids, or "krill", or even more if she is nursing a calf. Blues attack masses of krill with speed and power, often collecting enough water and prey in one mouthful to fill a swimming pool, squeezing the water out through their baleen before swallowing. If the krill are plentiful blue whales will congregate, as perhaps 200 did in the summer of 2001 off California. How do they know where food is plentiful? Before human noises flooded the ocean blue whales could communicate over thousands of miles. Do they tell each other where the food is, or do they hear other whales hunting and feeding?