These Incredible 'Chameleon Prawns' Change Color to Avoid Being Eaten

In nature, several animals have evolved the ability to change color in order to avoid being spotted by predators. One of these creatures is the aptly named chameleon prawn (Hippolyte varians), which can be found in rock pools and gullies in the coastal waters of northern Europe, among other regions. Usually measuring just over an inch in length, the color of these prawns is highly variable, ranging from red, brown and green to almost transparent with red or yellow blotches. Now, a team of scientists from the University of Exeter, in the U.K., and the Federal University of ABC, Brazil, has conducted a study—published in the journal Nature—revealing intriguing new details about the species' unusual camouflage abilities. Unlike true chameleons and animals such as cuttlefish, H. varians cannot change color immediately. Instead, their hue slowly adapts over time to the seaweed in which they live—which changes color with the seasons. "The chameleon prawn is tremendously diverse in terms of coloration and appearance," Sam Green, an author of the study from the University of Exeter, told Newsweek. "What drives this remarkable variation is of great interest to better understand function of animal coloration." "Most work investigating colour change has focused on species such as Cephalopods and fish that are capable of rapid changes to coloration," he said. "Slower colour changes are far less well understood as the duration of change will likely lead to some degree of mismatch between backgrounds, yet they are believed to be more common in nature." According to Green, the new study demonstrates the impressive ability of the chameleon prawn to camouflage itself among the seaweed in its environment. "We measured the camouflage of prawns to the vision of their predators and recorded color change in the lab, and found the prawns can improve camouflage against their new backgrounds over a number of weeks," he said in a statement. "Seaweeds vary seasonally in U.K. rock pools and this ability probably enables prawns to maintain camouflage throughout the year." But their ability to camouflage themselves doesn't stop there according to the researchers, who studied chameleon prawns living in rock pools in Cornwall—a county located in the southwesternmost tip of England. The study also shows how the prawns further adapt to their constantly changing environments—which often vary considerably in color and pattern across space and time—by choosing to hang out near seaweed that looks most similar to their current look. "As the rock pool environment consists of a variety of different colored seaweed patches, our behavioral experiments show that the prawns also select backgrounds that match their existing appearance," Green said. "This helps maintain camouflage in the short term, helping prawns to deal with the challenges of rock pool life. For example, a wave could dislodge a prawn from its chosen perch," he said. "This demonstrates how color change and behavior combine to facilitate camouflage in varying environments over different timescales." This article was updated to include additional comments from Sam Green.