Pharyngeal jaws are a "second set" of jaws contained within an animal's throat, or pharynx, distinct from the primary (oral) jaws. They are believed to have originated as modified gill arches, in much the same way as oral jaws.

The pharyngeal jaws of the moray eel

Although approximately 30,000 species of fish are known to have pharyngeal jaws, in many species having their own teeth, the most notable example of animals possessing them is the moray eels of the family Muraenidae. Unlike those in other fish known to have them, those of the moray are highly mobile. This is quite possibly a response to their inability to swallow as do other fish by creating a negative pressure in the mouth, perhaps induced by their restricted environmental niche (burrows). Instead, when the moray bites prey, it first bites normally with its oral jaws, capturing the prey. Immediately thereafter, the pharyngeal jaws are brought forward and bite down on the prey to grip it; they then retract, pulling the prey down the moray eel's gullet, allowing it to be swallowed.^[1]

[edit] In fiction

Probably the most famous example of pharyngeal jaws is the fictional extraterrestrial creature from the Alien film series called the "Xenomorph". In the films, Xenomorphs are depicted with a secondary, inner set of jaws mounted onto a proboscis inside of the throat, in place of a tongue. This proboscis can be rapidly shot forward with force to attack prey.

[edit] References

[edit] External links

• National Science Foundation article explaining moray eel pharyngeal jaws