In
crustaceans, the rostrum is the forward extension of the
carapace in front of the eyes.[1] It is generally a rigid structure, but can be connected by a hinged joint, as seen in
Leptostraca.[2]
In mammals, the rostrum is that part of the
cranium located in front of the
zygomatic arches, where it holds the teeth, palate, and nasal cavity.[6] Additionally, the
corpus callosum of the human brain has a nerve tract known as the rostrum.
The beak or
snout of a
vertebrate may also be referred to as the rostrum.
Some
cetaceans, including
toothed whales such as
dolphins[7][8] and
beaked whales, have rostrums (beaks) which evolved from their jawbones. The
narwhal possesses a large rostrum (tusk) which evolved from a protruding canine tooth.
Some
fish have permanently protruding rostrums which evolved from their
upper jawbones.
Billfish (
marlin,
swordfish and
sailfish) use rostrums (bills) to slash and stun prey.
Paddlefish,
goblin sharks and
hammerhead sharks have rostrums packed with
electroreceptors which signal the presence of prey by detecting weak electrical fields.
Sawsharks and the critically endangered
sawfish have rostrums (saws) which are both electro-sensitive and used for slashing.[9] The rostrums extend
ventrally in front of the fish. In the case of hammerheads the rostrum (hammer) extends both ventrally and
laterally (sideways).
The upper jawbones of some fish have evolved into rostrums
Sailfish, like all
billfish, have a rostrum (bill) which is an extension of their upper jawbone
^Todd A. Haney, Joel W. Martin & Eric W. Vetter (2007).
"Leptostraca". In James T. Carlton (ed.). The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon (4th ed.).
University of California Press. pp. 484–495.
ISBN978-0-520-23939-5.
Archived from the original on 2020-09-12. Retrieved 2020-09-12.