WHAT IS A WHALE ANYWAY?
Whales are mammals just like horses, dogs, cats and humans. All mammals have lungs, breathe air, have warm blood, bear live young, and the females have mammary glands which produce milk to feed their young. Most mammals also have legs and hair or fur.
WHALE EVOLUTION
Millions of years ago (about 65 million to be exact), the ancestors of today's whales are believed to have lived on land... not in the sea. These early whale ancestors were animals that looked much like modern wild dogs in Africa. It is thought that the availability of food on land became scarce (remember, 65 million years ago is when the Dinosaurs died out due to the aftermath of an asteroid striking the Earth near the Yucatan Peninsula in Mexico. The whole world was in flux!) and so the modern-whale-ancestors took to the ocean in search of food. As they spent more and more time in the ocean they gradually became adapted to life in the sea. The changes/steps that they underwent during this evolution are very well documented. In fact, the fossil record of whales from 65 million years ago to now is one of the most complete fossil lines known to science!
Whales still have "vestigial" traces of their land ancestry. For example, the skeletal structures of some whales still have the bones of hind legs, a pelvis, fingers, and some species of whale still have hair on the head!
Over the centuries, as whales gradually moved from the land back into the sea (remember life began in the sea), incredible adaptations in their anatomy occurred. The muscles of the upper rear legs have become a powerful tail stock, enabling some whales to swim at speeds of over 35 miles per hour. At the end of the tail stock evolved into a pair of horizontal "flukes" (together forming the animal's tail) that propels the whale forward by moving up and down through the water. A whale's nostril, called a "blow-hole", is now located on the top of the animal's head, so very little of the whale has to be raised out of the water when the whale surfaces to breath. The forelimbs of whales are now flippers of varying length, with a bone structure similar to a human arm and hand. The flippers themselves are used by the whales for balance when swimming, to make sudden changes in direction, to concentrate prey, and even to help cool the whales off (by pumping blood into the long, thin flippers the blood is cooled off by surrounding seawater before returning to the whale's body)!
MODERN WHALES
Today all Whales, Dolphins, and Porpoises belong to the same Order of mammals called the "Cetaceans". There are approximately 78 species of cetaceans in the world today (depending on which authority you talk too).
The order Cetacea is divided into three major groups: the "Odontocetes" or "Toothed-Whales", the "Mysticetes" (from the Greek word for "mustache"), or "Baleen Whales", and the now extinct "Archeocetes".
Odontocetes comprise the Dolphins, Porpoises, Orca or "Killer Whales" (which are technically dolphins), Sperm Whales and other whales with teeth.
Mysticetes comprise whales such as the Right Whale, Finback Whale, Minke Whale, Sei Whale, Bowhead, and many people's favorite, the Humpback Whale.
The Odontocetes or toothed-whales are the largest family of Cetaceans and they are usually quite small by whale standards. The vast majority of toothed whales are either dolphins or porpoises that rarely exceed 14 or so feet in length. The only "great" whale (or whale over 30 feet in length) that has teeth is the sperm whale like the one made famous in Herman Melville's novel "Moby Dick". (By the way, the story of Moby dick is based on the true story of the sinking of the whaling ship "Essex" that left the port of Nantucket in the late 1800's in search of Sperm Whales. The Essex and her crew sailed all the way down the east coast of North and South America, around Cape Horn, and up into the tropical Pacific, only to be rammed and sunk by an enraged male Sperm Whale... but that's just the beginning of the crew's ordeal. If you want to know more read "In The Heart of The Sea" which chronicles not only the sinking of the Essex, but also her crew's struggle to reach civilization after being set adrift in the middle of the Pacific. I don't want to ruin the story for you... but let's just say they got REALLY hungry;)
All of the odontocetes posses the amazing ability to "echo-locate". That is, they can send out blasts of sound and then listen for the echoes of those sounds to locate prey much like a bat flying through the night sky looking for insects. Once a prey item is located, a toothed whale will catch and consume one fish (or squid, etc) at a time.
The Mysticetes or baleen-whales are fundamentally quite different that the toothed-whales. All of the baleen whales are quite large, ranging in size from the 21 foot Pygmy Right Whale all the way up to the biggest of all animals... the giant Blue Whale (The largest Blue whale ever recorded was a 114 foot female taken in the Southern Ocean and processed at a whaling station on South Georgia Island).
The structure of the feeding mechanism inside a baleen whale's mouth is one of the most curious in nature. Instead of teeth they have a curious substance called "baleen" which allows them to filter small fish or plankton from the sea. Many of the very large baleen whales need to eat up to 3,000 pounds of food each day in order to sustain themselves. To do this they cannot afford to take just one fish at-a-time like the toothed whales do. To catch that amount of fish they have to target entire schools of fish at once and capture hundreds of pounds of fish in each mouthful.
But these whales have a problem... Remember that whales are mammals, just like us, and just like us they can't drink seawater. The ocean is, on average, about 3.5% dissolved salt and when a mammal such as a dog, cat, human, or a whale drinks seawater the salt pulls moisture from its body tissues and causes dehydration. Drinking too much seawater can be fatal for for any mammal... even a whale. (That's why the crew of the Essex couldn't drink the seawater when they were lost at sea!)
So how do baleen whales catch entire schools of fish without drinking a lot of sea water in the process? They strain or filter their food from the water using plates of "Baleen" (or "whale-bone" to the early whalers, although it's not actually comprised of bone tissue). These "baleen plates" are made of "keratin", the same protein that makes up your finger nails (and toe nails, and hair, and horses hooves, and scales on snakes, and the exo-skelleton of insects). An adult whale has between 600 and 1,200 individual baleen plates that are suspended only from the upper jaw of the animal and together they form a giant straining wall through which water can easily escape but the fish cannot (see photo to the right of a Right whale feeding). So the whale will simply dive beneath the surface and possibly listen for schools of fish beneath the surface (baleen whale can't echo-locate like the toothed-whales can so exactly how they find their food is not known for sure). Then they will open up their huge jaws and take in hundreds of gallons of fish and seawater at one time. The whale will then close its mouth almost all the way and squeeze the water out through the baleen plates. The water flows out through the narrow gaps between the plates, but the fish are left trapped inside. Now the whale can just swallow the fish whole and not worry about drinking an excessive amount of salt water.
But how do they get the fresh water they need? Well, they get fresh moisture in one of two ways...either through the food that they eat, or by the metabolization of their blubber layer. When the whales metabolize fat water is released as a by-product and the whales can re-absorb that water. Whales also don't have sweat, glands as we land-dwelling animals do, so they don't need as much fresh water per pound of body weight.
The length and number of the baleen plates inside a whale's mouth can indicate the kind of food that the whale prefers to eat. Generally speaking, the larger the prey, the shorter and fewer the baleen plates. That makes sense when you think about it... whales that eat relatively large fish such as Herring or Mackerel (5 to 9 inches long) need only have short baleen plates (or a smaller filter). Minke and Fin Whales are good examples of this as they have baleen plates that rarely exceed 3 feet in length and number between 600 and 900 on average.
However whales such Right Whales that eat only tiny, flea-sized crustaceans called "copepods" must have a giant filter to capture enough food to survive. The baleen of Right Whales can be 14 feet long and number well over 1,000 individual plates! Different baleen whale species have developed many different feeding strategies and, in places like Stellwagen Bank and Jeffrey's Ledge, many different types of these feeding strategies can be observed by the various species that feed there.
