The Pacific leaping blenny (Alticus arnoldorum) is an odd fish, one that has no legs yet leaps, and is aquatic, yet lives on the land.They are carnivorous finned creatures that use camouflage tactics to get the — jump — on their prey, which includes such animals as lizards, crabs, and sometimes birds, according to a news release by the University of New South Wales.
The Pacific leaping blenny has successfully transitioned from a life in the water to one upon the land, living in the splash zone upon rocks, where they blend in. They hop about, searching for prey, or in defense of their territory, or on the lookout for a mate. According to Doctor Terry Ord, of the UNSW School of Biological, Earth and Environmental Sciences, studying the blennies offers scientists “a unique opportunity to discover in a living animal how the transition from water to land has taken place.”
Doctor Ord and his research team studied five different colors of the Pacific blennies, comparing them to the habitats and types and colors of rocks that they made their homes. The researchers discovered that the camouflage of the blennies both allows them to sneak up on their prey and also to avoid detection from animals who might like to otherwise prey on them.
The camouflage of the blennies was not so ideal on the sand
Wondering how the blennies would fare if they were away from the relative safety of their rocks, where they blended in so well, Doctor Ord and his research team decided to test this out by creating realistic plasticine models of the fish and then they placed some of the models on rocks and some onto a nearby beach, where they would stand out and be seen more easily by other predators.
After a few days, they collected up the blenny models and compared how often they’d been attacked, based on “the marks in the plasticine.” It wasn’t a big shock to the researchers, to say the least, that they “found the models on the sand were attacked far more frequently than those on the rocks.”
Doctor Ord and his research team found that the predatory blennies are very well adapted to their specific rocky environments, and each color variety made great use of their camouflage abilities, locating the colored rocks that would best match with the colors of their bodies. Ord and his team theorizes that the blennies were already adapted to camouflage themselves using the rocks before they ever made their move to land.
How does the Pacific leaping blenny “leap” without legs?
The Pacific leaping blenny is a relatively small fish, only about four to eight centimeters long. It “leaps” by using a tail-twisting motion. The blennies have to stay moist throughout their lives, in order to be able to breath through their gills and skin; but, they live on the land their entire adult lives.
Doctor Ord, S. Tonia Hsieh of Temple University, and another coauthor of the study, Courtney Morgans — of the Evolution and Ecology Research Center — were among the researchers who traveled to Guam to study the Pacific leaping blenny.
Besides being a record of how well the Pacific leaping blennies have adapted to their environments and use camouflage to both attack prey and avoid being attacked, the blennies are also an excellent example of how sea life sometimes is able to make the transition from the sea to the land. The findings of Doctor Ord and his research team have been published in the journal Animal Behaviour.
Written by: Douglas Cobb
Pacific leaping blennies in action