The Deceiver
There are different hunting methods for preying fish in a coral reef. Some swim along the reef and attack potential preys, others hang out on a rock or coral block, waiting for the prey to just swim by. In both cases, the fish is attacking quickly. They bring their body velocity up to incredible speed around 2m/sec to strike. But there is one fish, who is doing it differently. It belongs to the first group, to the guys leisurely swimming along the reefs, checking for food. But apart from that, things are different. The fish I’m talking about is the slingjaw wrasse or Epibulus Insidiator of the lippfish family.
It’s an inhabitant of the reefs in the tropical and subtropical Pacific, Indian Ocean, and the Red Sea. Slingjaw wrasses display a sexdimorphism, the females being brownish with a yellow spot on the side, or all bright yellow. The males are somewhat bigger, up to 50 cm long, brownish, often with orange and yellow parts, and a black stripe through the eye. The special thing about the Epibulus is his way of hunting.
When seeing a piece to snack on, the slingjaw wrasse slows down and comes to a stop some centimetres away from the potential prey. Then it strikes with high velocity, but not with its body, but just its jaws. Due to a modified anatomy of the head bones and ligaments, the slingjaw wrasse can protrude its jaw 65 % of the total head lengths within milliseconds. The whole movement starts with two muscle groups pulling on two bones, causing the lower jaw to protrude. Around 35 ms after starting the strike, the jaw is fully expanded. Another group of muscles and bones causes a depression in the mouth, in order to suck in the prey. In this, the slingjaw wrasse is similar to all the other lippfish and actually most perch-like fish. A few milliseconds later, the jaw is retracted. Just 1/10of a second after initiating the strike, the jaw is back in the normal position. The fish then usually uses its pectoral fins to paddle back from the site of strike, before turning and swimming away, leisurely cruising the reef again.
This deceiving hunting technique, pretending to stay far away from the potential prey, gave it its name. Insidiator means “the deceiver”.
Story by Gabriele Kerber (founder of www.amocean.org)
