Whale

Overview
Whales entered the oceans some 50 million years ago, descendents of land-living mammals. In fact, genetically speaking their mostly closely related living relative is the hippopotamus. Each evolved from a common ancestor about 54 million years ago. The term whale can refer to all cetaceans, which includes dolphins and porpoises, or it can refer just to the larger ones. Using the term “whale,” however, can be a bit confusing, as some creatures such as the killer whale and pilot whale are actually species of dolphin, according to their scientific classification.

Some 80 species of whales live in waters all over the world, including the Northern Atlantic and Pacific oceans. They migrate to warmer waters in the southern portions of these oceans as the seasons change in search of food, breeding grounds and to birth live young. Whales vary in size, with some reaching lengths of 100 feet or more and weights of roughly 200 tons.

Whales live in large groups called pods, which vary in size and consist of family members and family friends. Their large numbers help to protect them from predators such as sharks and other whales. Whales can communicate with one another by making high-pitched sounds. It’s been said that scientists have picked up on “whale accents” depending on where the creatures live. As mammals, whales have lungs, not gills, and must return to the water’s surface for breaths of air. A blow hole on top of the whale’s head makes this possible.

Diet
A grey whale can eat up to 340,000 pounds of food per day during a 140-day feeding period, and a blue whale can consume as much as 8,000 pounds of krill (small, shrimp-like crustaceans) each day for about 120-day feeding period. During migration, whales eat very little if anything at all.

Whale methods for collecting and consuming food vary from species to species. The humpack whale eats mostly krill and feeds by taking in a large amount of water containing its prey. The whale then uses its baleen – tiny, bristly teeth – to filter the creatures from the water. Other whales that feed in this manner include the blue whale and the baleen whale.

Grey whales are benthic eaters, meaning they feed on bottom-dwelling organisms. To gather these bottom dwellers, the grey whale dives down and rolls on its side to grab a mouthful of mud and sediment. In turn, the grey whale uses its baleen to filter out small crustaceans like amphipods and tube worms.

Other whales feed on larger marine creatures. The sperm whale, for one, feeds on other whales, seals, squid, walrus and giant squid. In addition to krill, fin whales also feed on schools of fish. Beluga whales are opportunistic feeders, sometimes hunting schools of fish in small groups and also consuming squid and worms.

Reproduction
Most whales don’t begin to reproduce until later in life, maybe at 7 to 10 years of age. Mothers give birth to a single calf, life offspring, and spend roughly a year caring for their young so that mother and child form a very tight bond. It’s not uncommon for a female to have multiple partners throughout the mating season, as whales generally tend to not maintain fixed partnerships.

Young are born tail first, which helps prevent the risk of drowning. Mothers nurse their young by squirting milk into the offspring’s mouth, a compound similar to cow’s milk but with a higher concentration of fat and the consistency of cottage cheese, which prevents it from dissipating in the water.

Threats
No marine species remains unaffected by human intervention, and the same holds true for whales. Though commercial whaling for the most part is no longer in practice, its impact on whale populations – once abundant now scarce in many areas – can still be seen today. For example, grey whales in the Northern Atlantic are functionally extinct, while right whales in the Northern Pacific are in great danger of a similar fate. Whales are hunted for their meat and are manufactured into anything from lubricants to cosmetics. The International Whaling Commission banned the practice in 1986 and Iceland has complied with the moratorium since 1989. Commercial whaling resumed in 2006 in Iceland through a loophole, though a lack of consumer interest drove the country not to issue a quote for the 2007 season. Norway and Japan are the only countries in the world that allow the practice to persist.

Whaling is not the only threat to whale survival. Whales are threatened by water and noise pollution in their habitat. Naval use of sonar is harmful to whales and disorients them. Recent studies have discovered whales caught in drift nets (another problem for whales) exhibited signs of hearing loss. Since whales depend greatly on their sense of hearing to navigate their migratory routes, hearing loss is a concern.

Other known threats to whales include global warming, over-fishing and ship strikes.