Bluestriped Fangblenny

Plagiotremus rhinorhynchos, commonly known as the bluestriped fangblenny, is a fascinating species of combtooth blenny predominantly found in the coral reefs of the Pacific and 🌊 Indian Oceans, including areas from the 🌊 Red Sea down to Knysna in 🇿🇦 South Africa, and as far east as the Line, Marquesan, and Society Islands (🇵🇫 French Polynesia), extending north to southern 🇯🇵 Japan and south to Lord Howe Island. This fish reaches a size of up to 12 centimeters (4.7 inches) in length and is recognized by its multiple common names such as the bluestriped blenny, bluestriped sabretooth blenny, and tube-worm blenny, among others. Its name, Plagiotremus, derives from Greek, meaning 'oblique hole,' reflecting its unique adaptations.

The fangblenny is notable for its mimicry of the juvenile bluestreak cleaner wrasse, which allows it to blend in and take advantage of cleaner stations where larger fish congregate to have parasites removed. Unlike the genuine cleaner fish, the fangblenny employs a sneaky strategy: instead of cleaning, it bites the unsuspecting host, feeding on their skin, mucus, and sometimes scales. Remarkably, their venom contains opioid-like compounds, rendering their bite painless and disorienting the host temporarily, aiding in their swift escape.

These fish prefer clear, coral-rich environments, ranging from lagoon to seaward reefs, and typically dwell at depths ranging from 1 to 40 meters. When threatened, they seek refuge in abandoned worm tubes or small crevices and are occasionally known to bite divers. In terms of reproduction, the bluestriped fangblenny is oviparous, laying adhesive eggs that attach firmly to substrates, with larvae that drift in planktonic layers of shallow coastal waters.

Exhibiting two distinct color phases, the bluestriped fangblenny is either blue with a black stripe from snout to tail or orange with two narrow blue lines. This species leverages its color-changing ability to adapt to its environment: at cleaner stations, it adopts the appearance of the cleaner wrasse and in other settings, it alters its pattern to blend with surrounding fish shoals from where it strikes at passing fish. This sophisticated mimicry, akin to Batesian mimicry, is most effective when the fangblenny is less common than the real cleaner fish.

Unlike many other blennies, the bluestriped fangblenny is free-swimming and often observed solo or in pairs. Their intriguing behavior and adaptive traits make them a significant subject of study in marine biology, shedding light on the complex interactions and survival strategies within coral reef ecosystems.