New Hampshire PBS
   share this page
NATUREWORKS!
Home     About     Watch     Nature Files     Teachers     Order DVD     Contact

Dolphins, Whales and Porpoises

   Whales

Whales are mammals. They bear live young and feed them milk and they have lungs. They breathe air through a blow hole at the top of their heads. Whales often travel in groups or pods. They can be found in all the world's oceans! 

   Open Wide

BaleenThere are two groups of whales. The Mysticeti, or baleen whales and the Odontoceti, or toothed whales. The mysticeti have baleen instead of teeth and they have two blow holes. 

Benthos Baleen is as fringe of horny, blade-shaped plates that hang down from the whales upper jaw. The plates have bristles on them, like a brush. The whale draws water into its mouth and then pushes it out through the baleen with its tongue. The baleen filters out krill and other plankton that the whale scrapes up with its tongue. Humpback whales, right whales, blue whales and gray whales are all mysticetous or baleen whales.

Benthos Most baleen whales feed near the water's surface, but the gray whale is a bottom feeder. It skims the ocean floor and stirs up mud and silt, draws it in and then filters out its food. The right whale skims the water with its mouth open to draw in water and food. The humpback takes great swallows of water and then filters out the food. The odontocetous, or toothed whales, have one blow hole and teeth that can cut up food. Sperm whales, narwhals and beluga whales are toothed whales. Dolphins and porpoises are also toothed whales. The largest whale is the blue whale. It can grow to be more than 100 feet long!

   Thar She Blows!

BenthosWhales have to come up to the surface of the water to breathe. When a whale comes up for air, it opens its blowhole and blows out old moist air in a spout of air and water. Whales can often be identified by their spouts!

   Belly Flop

BenthosMany species of whales leap out of the water and land on their sides or backs. This is called breaching. Scientists think whales use breaching to communicate with others in their pod because the sound or the vibrations that they make when they crash into the water can travel for miles under the water!

   Deep Dive

BenthosWhales can dive great distances. The sperm whale can dive to depths of over 7,000 feet and can stay underwater for close to two hours. Before diving, whales fill their lungs with air and close their blow holes, then they collapse their lungs. The air travels through their blood and muscles. Their heart rate slows down and their blood flow is concentrated to their heart and brain. This way they get the most out of the air they have stored!

 
    Dolphins
BenthosDolphins are really small, toothed whales! There are 33 species of ocean dolphins, including the bottle-nosed dolphin, the spinner dolphin, the killer whale, the pilot whale and the common dolphin. Most dolphins live in the ocean, but there are five species of river dolphins that live in fresh water. They are all mammals. They bear live young and feed them milk. They have lungs and breathe air. They have fur - well, really whiskers - right after they are born. They lose the whiskers as they grow older. Dolphins have cone-shaped teeth. Most of the dolphin's diet is made up of fish and squid.
    Built for Speed
BenthosDolphins are very fast swimmers!  They have long, torpedo-shaped bodies; beak-like snouts and smooth skin. They have strong tail fins that they move up and down to help them move through the water. They have a blow hole at the top of their heads that they use to breath through. When dolphins are underwater, they don't hold their breath. The oxygen they need to stay underwater for long periods of time is stored in their blood and muscle.
    Just a Few Words
BenthosDolphins are very talkative. They don't have vocal chords, they make clicks and whistle sounds by squeezing air back and forth between air sacs that are just under their blowholes. They use the whistles to "talk" to other dolphins. This helps them identify members of their group and locate each other. The clicking sounds are used for echolocation. Echolocation helps dolphins identify objects, predators and prey. The clicking sounds are magnified and directed by the dolphins melon. The melon is a fatty bulge between the dolphins skull and blow hole. The sounds dolphins make travel out into the ocean. When the sounds hit an object they bounce back to the dolphin. The returning sounds travel through fat deposits in the dolphin's jaw. The sound vibrations then travel to the dolphins inner ear and then the brain!  Dolphins can then figure out how far away something is, where it is, how big it is and sometimes even what it is!
    Porpoises
There are six species of porpoises. Porpoises are often confused with dolphins. Porpoises have blunt noses and don't have a melon. Their teeth are shaped like a spade and they have sharp edges. They are usually chubbier and shorter than dolphins. They are mammals and have a blow hole.
































 


Advertisement: