Gulper eel

The gulper eels mouth can suddenly expand like a soap bubble to allow it to scoop up much larger prey, although the fish is thought to eat mainly small crustaceans. Its theorized that, because of the fishs tiny teeth, its ability to stretch to bizarre proportions is more of a backup plan if food gets scarce and large fish are all that are on offer. After inflating itself, the gulperalso known as a pelican eel because its scooplike feeding method resembles the large water birdsabruptly deflates its mouth and swims away. Very little is known about these creatures that live up to 6, 000 feet deep: why one might inflate and deflate itself like that, for instance. But new observations of another gulper eel, this one in the Gulf of Mexico, have some researchers speculating that the behavior happens when the fish feels threatened.