>The adaptation of fangs has been a game changer for 55 blenny species in six genera in the Indo-Pacific. Unlike their endlessly cute, unarmed cousins that must spend their lives close to hiding holes, sabertooth blennies (or fangblennies as they have come to be known) evolved into streamlined open-water swimmers able to keep predators at bay with the threat of weaponry. As if fangs didn't provide protection enough, species in genus Meiacanthus won a second evolutionary jackpot: the ability to inject venom through a groove in their curved canines. This potent combination of adaptations provides such an advantage that over time a smattering of similar-sized reef fishes evolved to mimic several species of Meiacanthus. This charade, an example of Batesian mimicry, allows the impostor a bit more freedom from predation when feeding in the open.
>After arriving home we contact longtime friend Bill Smith-Vaniz, an authority on the taxonomy and mimicry of fangblennies. His interest goes back to 1969 when as a graduate student he and his mentor, Victor Springer, Ph.D., a blenny man from the Smithsonian, traveled to the Gulf of Aqaba on a collecting trip. During the trip the pair decided to put three similar-looking blennies through a thorough test for mimicry. Their group of blue and yellow fishes consisted of a venomous Meiacanthus, the model; a nonvenomous fangblenny of genus Plagiotremus, which makes its living snipping scales off unsuspecting fishes; and a fangless bottom-dwelling Ecsenius.
>The scientists first had to find out for certain if their model was actually toxic. Springer — well established, married and the father of two — deferred to Smith-Vaniz, who in the best tradition of young graduate students allowed a maddened Meiacanthus, fresh from the lab tank, to bite him on his bare midriff.
>A venomous striped fangblenny, Meiacanthus grammistes, being mimicked by a juvenile bridled monocle bream, Scolopsis bilineatus
>"Stung like a bee, I wouldn't want to do it again," he chuckles over the phone from his home in Gainesville, Fla. "The wound turned red and formed a welt that lasted most of the day. But it was worth it. There was no doubt our model was venomous. Tell you what, I'll send you a set of my mimicry papers."
>On follow-up trips to the Gulf of Aqaba, Smith-Vaniz and Springer spent hours making observations underwater and hovering around aquariums with clipboards in hand. According to their co-authored paper, on their home turf the three blennies performed well, staying together 60 percent of the time in some combination or another. When offered up as food to a lionfish, a stonefish and a grouper in lab tanks, all the predators immediately spit out the venomous Meiacanthus, and from then on had little or nothing to do with blue and yellow fishes in general — the charade appears to be a win-win-win. By mimicking both the Meiacanthus and a defenseless algae-eating blenny, the scale-nipping Plagiotremus can more easily sneak up on prey. And the defenseless bottom-grazing Ecsenius can extend its feeding range by palling around with its model. At the same time the Meiacanthus' warning colors get advertised broadly.
>© Alert Diver — Q4 Fall 2015