I n 2003, Leo Smith was dissecting a velvetfish. Smith, an evolutionary biologist at the University of Kansas, was trying to figure out the relationships between mail-cheeked fishes, an order that includes velvetfishes, as well as waspfishes, stonefishes and the infamous lionfish. As he worked his way to the velvetfish’s upper jaw, though, he realized something strange—he was having trouble removing the lachrymal bone.
“On a normal fish, there’s a little bit of connective tissue and you can work a scalpel blade between the upper jaw and this bone,” recalls Smith, whose work centers on the evolution of fish venom and bioluminescence. “I was having just a horrible time trying to separate it. When I finally got it separated, I noticed there was this thing that’s all lumpy and bumpy … it was then that it hit me that it had to be some sort of locking mechanism.”
To be fair, most velvet fish already resemble thorny, blobby mutants, so an extra skewer isn’t really that unusual. But given that Smith has spent years studying mail-cheeked fishes (Scorpaeniformes)—an order that gets its common name from the bone plates found on each cheek—you’d think he would have noticed a massive, locking eye spike before. He hadn’t. He and his colleagues would dub this strange new discovery the “lachrymal saber.”
(FYI: Lachrymal comes from the Latin word for “tear.” While fish can’t cry, it’s still the technical name for the bone forming the eye socket.)
Smith and his co-authors at the American Society of Ichthyologists and Herpetologists describe this unlikely eye spike for the first time in the journal Copeia—and even report on one that glows fluorescent green, a little eye lightsaber. The authors can’t yet say exactly what the appendage is for. But they do claim that it has the potential to profoundly rearrange the Scorpaeniformes evolutionary tree, changing what we know about these highly venomous fish.