Weird fish of the week: Sling-jaw wrasse

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Many fish species have evolved strange and unusual mouthparts to help them feed, but few if any have gone to the lengths of the Sling-jaw wrasse (Epibulus insidiator).

As soon as you've seen one of these fish in feeding action their common name becomes completely self explanatory.

They possess the most extremely extendable jaws ever recorded in fish, that can shoot out to over half of the fishes' length.

Their super-sized snout extension allows the fish to snatch up prey hidden between branching corals or sheltering in crevices.

This jaw-dropping feat is achieved by some remarkable mandibular mechanics. The lower jaw is almost free floating and in combination with the other mouth bones, muscles and ligaments, forms a tube as it's catapulted forward, sucking up its victims in under a 30th of a second.

Observations of feeding behaviour in the wild also record larger fish flipping over stones and gulping up mouthfuls of sand and debris from underneath. The fish then swims quickly upward, spitting out inedible items but snatching up any tasty morsels that make a dash for the safety of the seabed.

Sling-jaws are protogynous hermaphrodites – they all start life as females, with larger fish becoming male. They also display major sexual dichromatism with females being a light brown or yellow colour while the males have yellow/brown bodies with green edged scales, white heads with a dark stripe behind their eye and a fiery orange back. Check out the one on the video below:

They are a tropical species, resident on reefs within in the Indo-Pacific at depths up to 42m, with big males growing to around 50cm/20" while females are considerably smaller.

Young fish migrate to new territories by drifting with mats of floating leaves which attract a steady supply of potential small fish prey as it floats on the ocean's surface.

In 2008, a second, smaller species of Sling-jaw Epibulus brevis was described from the Western Pacific.

Why not take a look at some of our other Weird fish of the week features?

Barreleye 

Mega mouth shark

Flying gurnard

Pinecone fish

Slender snipe eel

Tripod fish

Lumpsucker

Ocean sunfish

Two-headed arowana

Stargazers

Giant oarfish

Kroyer's deep sea anglerfish

Halimeda ghost pipefish

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