New England Seabirds

Other Sea Life

Cetaceans Index

Page 1
Taxonomy of whales and dolphins

Page 2
Behaviors of whales and dolphins

Taxonomy of Whales and Dolphins Page 1
Order Cetacean
Whales, dolphins, and porpoises belong to the mammalian order Cetacean. Like all mammals, they must breath air.  Cetaceans spend their entire lives in water. They do not come onto land to breed or mate or to give birth. A few have adapted to fresh water, but most live in the marine environment. Cetaceans are carnivores. They may eat fish or crustaceans or even larger animals.

Cetaceans evolved from land animals that returned permanently to living in water. The front limbs of Cetaceans have become the pectoral flippers used to change direction when swimming. The hind limbs exist only as residual structures.  The tail moves up and down to produce forward motion.

The nose has migrated from the face to the top of the head so that they can breath in and out without lifting their mouth from the water, an adaptation that any serious swimmer can tell you is valuable. The mouth and digestive track are not connected with the lungs and the air passages unlike our system which allows us to choke on a piece of food.

The Cetaceans can be divided into two suborders: the Baleen Whales, and the Toothed Whales (includes dolphins and porpoise).

Baleen Whales Suborder Mysticeti

Filter Feeders
The Baleen Whales lack teeth and instead have baleen plates which are fingernail like horny plates which hang from the upper jaw. Baleen Whales feed by swimming through school of bait fish, filling the mouth with water and food. When they finish their swim they rise to the surface, close their mouth forcing the water thru the baleen plates which filters the food particles out of the water. This is why they are called filter feeders. 

This photograph by Peter Trull of the open mouth of a Humpback Whale shows the baleen plates that hang from the upper jaw and the expanded throat pleats which shows the whale has been swimming through the water with its mouth open capturing both food prey and water.

Most Baleen Whales have pleats in the  skin of the throat which can expand when filled with water.  Right and Bowhead whales lack these throat pleats.

The whale is now closing its mouth pressing the water out through the baleen plates and capturing the prey items in the mouth. The birds know that some prey will escape and are there to grab their share.

It is interesting that some of the largest animals on earth feed on small prey like plankton and small fish.  In order to survive the large filter feeding whales need schools of prey.  They cannot catch sand eels one fish at a time.  Fishing using large drag nets scatters the schools of fish and deprives whales of their livelihood forcing them to move on.

Right: Humpback Whale breech showing the throat pleats that expand when filled with water and food. Photo by Emmalee Tarry

Two Blow Holes on top of head
The Baleen Whales have double nostrils or blow holes on top of their heads. Toothed Whales and dolphins have only one.

The blow hole of a whale corresponds to the nose of land mammals. Whales and dolphins have the blow hole on top of the head, the most convenient place for an animal that lives in the water. This is not true of seals, or sea lions who must lift their entire head to breath.

This excellent photo by Jim Besada shows the two blow holes of a Humpback Whale.  Notice also the long white flipper which you can see under the water on the whale's left side.  The  Humpback Whale is the only  whale with long flippers.

Four Families of Mysticeti or Baleen Whales
There are four families of Mysticeti, two of which have species that can be seen in the  North Atlantic. Species usually or rarely seen in New England are in bold letters.

Toothed Whales Suborder  Odontoceti

The Suborder Odontoceti includes:   Toothed whales, dolphins, and porpoises.   All have teeth of some variety although not necessarily used for chewing and not visible in the water. One blow hole rather than two. Kinze (1994)

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Folkens, Peter (2002) Guide to Marine Mammals of the World Alfred A. Knopf New York

Kinze, Carl Charistian (2001) Marine Mammals of the North Atlantic Princeton University Press Princeton NJ