A spiny, beautiful fish is invisible to the small creatures it likes to eat
We know that lions rule the world’s savannahs, at least, that’s what stories like The Lion King have led us to believe, but could they also rule the aquatic world? According to scientists from James Cook University, the red lionfish uses a handy trick to be undetectable by their prey, which in turn rapidly increases the lionfish population size in areas where they’re not wanted.
Ever since their introduction in the Caribbean in the 1980s, the fish have been eating their way through the coral reef ecosystem. Researchers Oona Lonnstetd and Mark McCormick thought it would be interesting to see why they are such successful predators and hunters.
“Lionfish are such amazingly beautiful creatures with their striking colour patterns and long spines, but they are very rarely seen on the Great Barrier Reef,” Oona told Wonder of Science. “However, in another part of the world they are super common and becoming quite a nuisance, just like cane toads are a huge problem in Australia.”
The researchers used a technique called associated learning in their experiments. Basically, small prey fish learn who the dangerous predators are by associating the smell of their wounded fish buddies (bitten by a predator) with the smell or sight of that same predator. So the next time they see that predator they know that it’s dangerous and that they should hide. The researchers taught little blue-green chromis that three different predators were dangerous (the red lionfish being one of them) and then looked at how well they learnt about these predators by examining how they behaved.
“We found that red lionfish are largely invisible to the small fish that they eat. In fact, they are almost like ghosts, as the small Chromis do not appear to be able to learn that they are a threat and allow the lionfish to simply swim up and eat them,” explains Oona. “This was very different from their response to the other predators, from which they learnt to hide from right away.”
Red lionfish don’t look like a typical fish. With their large extended pectoral fins and spiny, colourful appearance they can easily be mistaken for a coral of some kind. This kind of camouflage is what researcher believe helps them remain undetected by their prey, and possibly even by other predators.
When a new species is introduced it unbalances native ecosystems. Usually these species do not have a natural predator, a specific animal that likes to eat them, which is a possible reason as to why the Red Lionfish population is getting out of control in the Caribbean and not the Great Barrier Reef. However, more research needs to be done to know for sure.
Lionfish are such cool and beautiful creatures. They are amazing to look at but we must remember to never touch them, as they have poisonous spines and getting stung by them hurts a lot!
Source [James Cook University]
Camouflage is a strategy often used by animals to hide from predators. They do this by either changing their colours to match their surroundings, or by living in a habitat that complements their colouring or their shape.