The blue whale is the largest animal that has ever lived on Earth; a blue whale can grow about 110 feet (33.5 meters) long. A fin whale grows to roughly 65 to 85 feet long, second only to the blue whale in size; gray whales grow to about 40 to 50 feet long and weigh roughly 40 tons or more; a blue whale's heart is as big as a small car. The fin whale is one of the fastest whales and can cruise at nearly 23 miles per hour; fin whales eat krill, small fish and squid. A fin whale can eat up to 2 tons of food in a day. A blue whale's spout can shoot up about 30 feet (10 meters) into the air; sperm whales dive deeper than 2,000 feet and can stay under for 45 minutes or longer.
Blue whale numbers today are only a small fraction of what they were before modern commercial whaling; whalers hunted North Atlantic right whales close to extinction. As of November 2026, blue whales are still endangered and are protected by law in the United States. As of November 2026, fin whale numbers are low because of past overhunting, and today the major threat is being hit by ships. As of July 2026, fewer than 400 North Atlantic right whales are left, which makes them one of the rarest great whales. As of July 2026, right whale mothers once had a calf every 3 or 4 years. Now females average one every 7 to 10 years, which slows the recovery of the species. Ship strikes and getting tangled in fishing gear are two big dangers for whales; each fall, some right whales travel more than 1,000 miles from their feeding grounds to winter calving grounds off Florida and Georgia.
A sperm whale's head holds an oily spermaceti organ. One source says it helps focus sound, and another says its exact job is not fully known; DNA points to the hippopotamus as the closest living relative of whales, while fossils of a small deer-like animal called Indohyus suggest it was even closer kin; scientists think some bowhead whales may live to be over 200 years old. Baleen is made of keratin, the same protein as human nails and hair. Because keratin rarely fossilizes, it is hard to tell when baleen first evolved, though the earliest known baleen whales lived about 30 million years ago; whales and dolphins alternate which half of the brain sleeps, so each half gets about the same amount of rest overall. This half-brain sleep is thought to let them keep swimming, breathing and watching for danger; female orcas stop having calves at around age 40, but may live decades longer. Menopause is known for sure in only six living species, orcas among them.
Whale bodies that sink to the sea floor are called whale falls. Scavengers strip the soft tissue in a matter of months; a dead whale on the sea floor feeds a whole community, from large scavengers to tiny bacteria; a dead whale's skeleton can feed deep-sea life for years or decades. A single whale fall can give the deep sea as much food as several thousand years of marine snow, the slow drizzle of dead material from above; Zombie worms of the genus Osedax, whose name means bone devourer in Latin, were first found on a whale fall in 2002.
As of November 2026, humpback whales are recovering in much of the world, though the species is still a conservation concern. As top predators, whales help keep ocean ecosystems in balance.
Words to know
- endangered: nearly gone
- conservation: protecting species
- ecosystems: living web
- spermaceti: whale oil
