In dark alleys of the Pacific and Indian oceans, new research shows some of the deadliest, armored fishes on the planet are packing switchblades in their faces.

A study from the University of Kansas appearing in the journal Copeia details for the first time evolution of a “lachrymal saber” unique to stonefishes — a group of rare and elaborately dangerous fishes inhabiting Indo-Pacific coastal waters. The new finding rewrites scientific understanding of relationships among several groups of fishes and reveals a previously unknown defensive strategy — also, it likely will fuel a few nightmares.

“I don’t know why this hasn’t been discovered before,” said William Leo Smith, associate curator at the KU Biodiversity Institute and Natural History Museum and KU associate professor of ecology & evolutionary biology. “It’s probably because there are just one or two people that ever worked on this group. We took five or six families and were able to resolve the problems in their classifications. To have this really strong anatomical feature visible from the outside is really helpful. To have a big map of how everything is related and evidence for it is what we’re all hoping for. We have this feature and get into the genetics of how it could have evolved.”

All stonefishes Smith examined in the study feature a mechanism he and his colleagues dub a “lachrymal saber” located on each cheek below the eye. Moreover, genetic analysis of 113 morphological and 5,280 molecular characters for 63 species reveals stonefishes possessing the lachrymal saber are closely related, producing a revised taxonomy of flatheads, scorpionfishes, sea robins and stonefishes.

 

Continue reading at University of Kansas.

Image via University of Kansas.