The first observations of hagfish hunting live prey, rather than scavenging, are revealed in video sequences described in the journal Scientific Reports.
Hagfish (Myxinidae) are a family of jawless, marine pre-vertebrates, known for their ability to produce copious quantities of gill-clogging slime when threatened. They are thought to feed through opportunistic scavenging but their abundance in the deep sea and analyses of their stomach contents have suggested that hagfish are unlikely to be sustained by scavenging alone.
Vincent Zintzen and colleagues analyzed images from baited video cameras and report that hagfish can be active and successful hunters. Hagfish slime appears to have multiple functions: as well as deterring potential gill-breathing predators, it can decrease competition for food by excluding other scavengers, and may also be used as a predation tool, incapacitating prey through suffocation. This unique combination of functional traits may have evolved in response to the evolution of more highly developed jawed fish and other vertebrates, the authors speculate, and could have contributed to the persistence of this family over the past 300 million years.