mackerel shark

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of various large sharks of the family Lamnidae, including the great white shark, mako, and porbeagle, having a pointed snout with large teeth and a crescent-shaped tail.

from The Century Dictionary.

• noun One of several kinds of sharks, as Isurus dekayi, or the porbeagle, Lamna cornubica.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Any shark of the order Lamniformes, having two dorsal fins an anal fin, five gill slits and eyes without nictitating membrane

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun fierce pelagic and oceanic sharks