Photo by SeaWorld, Inc.
Length: longest—blue whale Balaenoptera musculus is 70 feet (21 meters); shortest—Hector's beaked whale Mesoplodon hectori is 4.5 feet (1.4 meters)
Weight: blue whale—63 tons (64.4 tonnes); Hector's beaked whale—105 pounds (48 kilograms)
Life span: some species are thought to live more than 100 years
Gestation: 9 to 17 months, depending on species
Number of young at birth: 1
Size at birth: 1/4 to 1/3 the length of the mother
Age of maturity: males—4 to 35 years; females—4 to 28 years, depending on species
Conservation status: 11 species are endangered, including blue whale, sperm whale Physeter catodon, and humpback whale Magaptera novaeangliae.
Killer whales Orcinus orca are part of
the Cetacea order but share a taxonomic family with dolphins.
Unlike fish tails, which are flat-sided, whales' tails are perpendicular to their bodies, like an airplane's tail. Whales use their tails in an up-and-down motion to swim, whereas fish use a back-and-forth motion with their tails.
Baleen is made up of tough, flexible strands of keratin that hang down from the top of the whale's enormous mouth.
The blue whale is the largest mammal to have ever lived on Earth.
Gray whales Eschrichtius robustus make the longest migration of any whale, traveling from Alaska to the coast of Mexico. This is a round-trip journey of more than 12,000 miles (20,000 kilometers).
Listen to a humpback whale!
Mammals of the sea
Whales come in different sizes, but they all have smooth skin, flippers, and flat tails (called flukes) that propel them through the water. They give birth and nurse their young in the water and live their entire lives there. Their specialized noses and ears have adapted to life underwater. They have excellent vision and large, intelligent brains.
Whales are divided into two groups: toothed and baleen.
There are 69 species of toothed whales, including sperm whales Physeter catodon, beluga whales Delphinapterus leucas, and narwhals Monodon monoceros. Bottlenose dolphins Tursiops truncatus, and killer whales Orcinus orca are in this group as well. Toothed whales have one blowhole (adapted nostril) on top of the head that divides into two nostrils inside the head. They use echolocation to find food. These whales eat fish, octopus, squid, and crustaceans like shrimp.
There are 13 species of baleen whales, including the gray whale Eschrichtius robustus, blue whale Balaenoptera musculus, and humpback whale Megaptera novaeangliae. Baleen whales are much larger than most toothed whales and have a double blowhole on top of the head. Baleen whales gulp huge amounts of seawater, then strain out the water to catch the zooplankton (tiny animals) and krill (tiny shrimplike creatures) that they eat. Gray whales suck up mud from the ocean floor and strain out the small worms and crustaceans that live there. Scientists are still studying whether or not baleen whales use echolocation.
Toothed whales make sounds that travel underwater. The sound waves bounce off an object and then return to the whales as echoes. Submarines use the same method to navigate through the ocean. This echolocation allows the whale to find food or avoid predators, even in dark or murky water. Research has proved that the sounds come from deep inside their heads, not their throats as with other mammals. The sounds come from air vibrating through their complex nasal passages.
Down, down, down to the bottom of the sea
Whales have special adaptations for diving. They generally dive on a full breath of air. The air in their lungs is compressed by the sea's pressure as they dive. When they dive, their bodies use less oxygen by sending it to vital organs such as their brains, hearts, and lungs where it's needed most. Their heart rate slows down, and they can tolerate higher levels of carbon dioxide than humans. Sperm whales are champion divers, often diving more than 1 mile (1.6 kilometers) deep for more then one hour!
Whales make lots of different kinds of sounds, including trills, whistles, moans, and squeals. Whistles seem to be used mainly for communicating with other whales. Single male humpback whales make their famous whale songs during the winter mating season.
Human impact on whales
Humans have hunted whales, mainly for their blubber (oil), for thousands of years. Present-day whalers use the meat as well as the blubber. At first, small-scale hunting did not affect whale populations. But in the last 200 years, humans have built bigger ships and better equipment to hunt and kill larger whales in faraway oceans. Humans have hunted whales for their meat, baleen, oil, and hides. Whale hunting, pollution, and human development along oceans and rivers have seriously impacted some whale populations.
The good news is that not all whales are endangered. Of those that are endangered, some populations are at higher risk of extinction than others. One great success story is the gray whale, which was hunted to the brink of extinction twice, and now has completely recovered due to protection and conservation efforts.