Whale is the common name for various marine mammals of the
order Cetacea. The term whale is sometimes used to refer to
all cetaceans, but more often it excludes dolphins and porpoises,
which are also cetaceans but belong to the suborder Odontoceti.
This suborder also includes the sperm whale, killer whale,
pilot whale, and beluga whale. The suborder Mysticeti (baleen
whales), are filter feeders that feed on small organisms caught
by straining seawater through a comblike structure found in
the mouth called baleen. This suborder includes the blue whale,
the humpback whale the bowhead whale and the minke whales.
All Cetacea have forelimbs modified as fins, a tail with horizontal
flukes, and nasal openings on top of the head.