Whales are large marine mammals belonging to the taxonomic order Cetacea. They come in two varieties: Odontoceti comprising of the carnivorous toothed whales, and Mysticeti comprising the unique filter feeders that strain plankton, krill and other organic matter into their stomachs through the use of baleen. Many whales are huge in size; the blue whale is the largest living creature ever known to have existed on the planet. They are usually long-lived, with some individuals known and recorded as having lived for more than a century. Despite the overhunting in the 18th century, whales are slowly gaining their numbers back in the wild.
As mammals, whales are warm-blooded, air-breathing creatures that give birth to live young and even have body hair. Despite a generally fish-like appearance, whales do not resemble fish in the slightest at the biological level. Whales have a four-chambered heart and spinal column as well as dorsally mounted blowholes that function as nostrils helping the creature breathe while partially underwater. The whale ear is especially acute, being capable of directional hearing of faint whale songs from far off distances underwater.
Many whale species, including the humpback whale, communicate through the use of melodic whale songs that can sometimes be heard for miles in distance from the individual. Whale songs serve can serve to communicate a wide variety of information to whales in the surrounding area, including self-identification. Whales also have a mechanism for vocalizing a loud “click” that is used for echolocation. The highly developed ear of the whale is ideal for interpreting the echoes of these clicks, which can often be the loudest sounds in the ocean and even interfere with sonar devices of ships.
Whales are predators, although the creatures that they eat vary widely. Toothed whales prefer to eat smaller fish, squid – the sperm whale’s favorite food is giant squid, and it remains the only viable predator for the species. Killer whales are known to eat just about anything, including mammals and even other whales. Baleen whales like the enormous blue whale live off of krill that they filter out of the water by taking huge mouthfuls of seawater and forcing it through the thin, comb-like structures, leaving the creatures stranded within the whale’s mouth. Whales do not drink seawater as is commonly believed, but, instead, take water out of their food, when metabolizing it.