The reef's most accomplished fraud. This blenny copies the cleaner wrasse - the blue and black stripes, the hovering, even the little dancing motion cleaners use to advertise themselves - and it works well enough that fish queue up for it.
Then it bites. Instead of picking off parasites it takes a mouthful of mucus, skin or fin from the customer and bolts. Fish that have been robbed learn to avoid the pattern, so the blenny switches: individuals change color to match whatever cleaner or damselfish is common locally, and a population under pressure shifts its whole appearance.
The teeth are the equipment. Two enormous curved fangs sit in the lower jaw, grooved and connected to a venom gland - and the venom is not for killing. It contains opioid-like peptides that drop the victim's blood pressure and disorient it, so the bitten fish loses interest in chasing rather than being harmed. A predator that swallows the blenny gets the same dose and spits it out.
Twelve centimeters (5 in) of fish that lives entirely on other fish's tolerance, and one of the very few venoms on this reef used for escape rather than for attack.
The genus. Plagiotremus Gill 1865 - plagio- (oblique) + trema (hole). ETYFish
The species. Plagiotremus rhinorhynchos (Bleeker 1852) - rhinos (beak or bill) + rhynchos (snout). ETYFish
- slender body with two blue-black stripes, colors switchable between blue, orange and black
- hovers in open water rather than perching, unlike most blennies
- swims with a wriggling, back-and-forth motion copied from the cleaner wrasse
- length up to 12 cm
Why it's threatened
There are no known major threats.
Threat classification from the IUCN Red List.
