Blue Whale
BLUE WHALE (Balaenoptera musculus)
The blue whale is the planet's biggest animal, growing to lengths of over ninety-five feet (twenty-nine meters) and weighing up to one hundred and ninety-nine tons. These spectacular baleen whales are found across all the world's oceans, except the Arctic. Although their populations are now increasing, blue whales are still classified as endangered, with a global population of less than 20,000 mature individuals.
Difficulty: Medium
Blue Whale Description
The blue whale is not only the world's largest whale, but the largest animal to have ever lived on this planet. Blue whales measure up to 98 ft (29.9 meters) and weigh up to 199 tons. They are baleen whales, characterized by the baleen, rather than teeth, they use to sieve krill from the water. Blue whales are grayish-blue in color on their dorsal side, with a slightly lighter underside. Their overall body shape is quite slender, with a U-shaped head. Two blowholes can exhale air over thirty feet into the air (nine meters). They've got a small dorsal fin, located close to the tail. Like most other baleen whales, blue whales have dark colored baleen, up to 395 individual plates. The female blue whales we hope to encounter during our Gray Whales and Blue Whales of Baja photo tour are smaller than the largest recorded whales, but still average around seventy-two feet (22 meters) in length.
Blue whales are massive. The whales we see in Baja California, in the Sea of Cortez are generally over seventy feet long. Notice how far back their dorsal fin is located. Photo by Ajit S N.
Blue Whale Distribution and Habitat
Blue Whales are found in all of the oceans except the Arctic Ocean. They are broken down into eight different subpopulations, including the eastern North Pacific population. These are the blue whales we see on our Baja Blue Whale Tour. There are an estimated one thousand adult animals living in this population of blue whales. They feed in the California waters during the summer and fall (where you might see on our Sea Otters and Whales of Monterey Bay tour), then swim northwards for the late fall, and then migrate down to Baja in the winter. Blue whales are not coastal-dependent, but rather utilize any area of the ocean in which food can be found. In the Sea of Cortez, where we see blue whales during this tour, females come to give birth. Despite their size, the movement patterns of blue whales are still not well-understood.
We encounter blue whales when they are traveling into the Sea of Cortez to mate, give birth, and to feed. However this is probably not their most southernly stop on their migration. It is believed they spend the winter feeding in waters off of southernly Mexico and central America.
Blue whales are just as home near coastal waters as they are in the open ocean. Where they go depends on their prey availability. We will encounter the Blue Whales in the Sea of Cortez. We also have a chance to see them in the Monterey Bay.
Blue Whale Feeding Biology
Blue whales, the largest animal on earth, feeds on one of its smallest, krill. Blue whales lunge feed at their prey, either below or at the surface. They swim rapidly toward a krill swarm, open their mouths up to eighty degrees, being able to do so because of their approximately seventy throat grooves. With one gigantic gulp, they are able to take in as much as 220 metric tons of water. They will push that water out through their baleen, catching the krill in the process. With a highly successful lunge, blue whales may gain 450,000 calories of shrimp. It is estimated that blue whales need to eat around 2,500 lbs of krill a day to meet their energy requirements. It is rare to see blue whales feed in conjunction with other whale species, potentially to avoid competition with each other.
Blue whales specialize on eating krill, some of the smallest ocean organisms. They need to eat around 2,500 lbs of krill every day to survive. Photo by Apple Pho.
Blue Whale Social Organization
Blue whales are generally solitary animals, traveling by themselves or in pairs. In exceptionally good feeding locations, there may be as many as fifty blue whales foraging at one time. To communicate with each other, blue whales produce some of the loudest and lowest frequency populations out of any animal. Their vocalizations range from eight to twenty-five hertz. Males will produce pulsed and tonal calls, often in sequence in each other. Since females don't produce these sounds, it is assumed this has to do with mating in some fashion. Both blue whale sexes also produce down swept tones when feeding as well as by males when competing for females. It is believed that blue whale calls can be heard by other individuals over 1,000 miles away, due to their low frequency.
Like other whales, blue whales spy hop, tail slap, and even breach, but they do none of these activities commonly, nor do they raise much of their body out of the water during a breach. None of these activities therefore seem like a commonly used form of communication for blue whales.
Blue Whale flukes are often seen when the whales are diving, but tail slapping is rarely observed. The whales seem to rely much more on calls for communication. Photo by David Serradell.
Blue Whale Reproduction
Blue whales are sexually mature at around nine years old. They only mate and give birth during specific months of the year, though little else is known about their mating behaviors. It is believed that multiple blue whale males compete over the mating rights to a female. Calving takes place in winter, after a gestation period of eleven months. Female blue whales give birth to a single calf every two to three years. At birth, the calf is around six meters (20 ft) long and weighs two tons. Blue whale calves can gain around 200lbs every day from nursing and separate from their mothers at around seven months old. It is estimated that blue whales live around eighty to ninety years in the wild.
A blue whale mother and her calf in the Sea of Cortez in Baja California Mexico. Blue whales come to the Gulf of California to give birth and breed, which is our perfect opportunity to see them. Photograph by David Serradell.