One family of moderately-armored fish eats other armored fish. They have mouths between their skulls and each skull forms a single jaw that can be used for the mouth above it or below it. They may have anywhere from two to six mouths, often with different types of teeth. These fish range in size from three centimeters to over two meters long. In order to crack open the armor of their prey, they use the combined force of all their jaws pressing down onto a single pair of jaws that holds the meal. Most species also have muscular lobes on the dorsal and ventral surfaces that will bend forward and squeeze the jaws tightly shut.
Distant relatives of the open-sea vicers, tailvicers have only two jaws and one mouth. They lack the dual muscular lobes to apply additional pressure to the jaws, but instead make use of their long tail to wrap around their jaws to constrict them. This is helpful when trying to bite through an armored saw lobster or spine-tail. The nervous systems of these creatures are divided into two brains – one in the head to control the jaws, and one at the base of the tail for greater dexterity and response times (the tail also prevents prey from getting away). Although they usually remain in zones too dark for them to be of any use, these false fish have a pair of small eyes at the base of the tail. Just behind the head are large, inflatable/collapsible ears for hearing the sounds of creatures crawling under the mud.