Terrestrial species such as birds, bears, and humans have adapted to fish for food in water, be it with a specialized beak, mighty paws, or a delicate flying lure. The same can happen in reverse with fish firing down meals with a spurt of water or leaping from the ocean to swallow a bird. A new study published in the journal Fish Biology details the interesting case of a badass triggerfish that launched itself onto land in pursuit of crabs.
Aptly named the titan triggerfish, these lightning-quick fish are voracious predators. Growing to around 75 centimeters (2.5 feet) in length, they’re known for their aggression by divers who are frequently nipped by their powerful teeth as the triggerfish fiercely defend their nests. It wasn't until Matthew Tietbohl, a coral reef ecologist at King Abdullah University of Science & Technology in Saudi Arabia, visited the Red Sea’s Mar Mar Island to survey a beach for sea turtle tracks that the triggerfish’s unusual hunting strategy was discovered.
“We turned to see this triggerfish launching itself into the shallows and stranding itself,” said Tietbohl in an interview with New Scientist. Stranding is a risky behavior for most fish who can’t breathe on land, so what could motivate such a bold strategy? The triggerfish was going after ghost crabs, which are common at the water’s edge as they graze on algae attached to the rocks.
Tietbohl reports that the fish would lay in wait like a stalking crocodile before launching itself out of the water to grab a crab and drag it back into the sea. It asks interesting questions about the fish's vision as to accurately calculate where a target is from beneath a water surface that refracts light differently to air is quite a feat.
Triggerfish are smart eaters that will flip urchins to access their gooey underbelly, so it’s no surprise that they might exhibit such out-the-box thinking. To see a saltwater fish stranding itself however is unusual, as most fish known to do this come from freshwater environments. As such, Tietbohl and his team want to find out if this explosive, lay-in-wait hunting strategy style is used by other related species, or if it’s even widely practiced among titan triggerfish. While they saw other triggerfish that appeared to be “patrolling” in the shallows they only spotted one visionary launching itself onto the rock.