It’s often said that the oldest and biggest fish in the lake make the greatest adversaries.
That’s because they’re shrewd, wiley and having found themselves on the wrong end of rods and fishing reels many times before, know how to avoid capture. But now there’s concrete evidence that fish are far more intelligent the ‘goldfish’ brains we’re led to believe they are.
In fact, it turns out fish are equally as clever as many mammals and in some cases outdo their land dwelling cousins. Just because fish are the oldest of the planet’s vertebrates, doesn’t mean they stopped evolving, just that they’ve been evolving for longer.
Intelligent as chimps
Some fish are so brainy, they compare favourably to chimps, and among the cleverest of the lot are coral trout, and their close relative, the roving coral grouper. Just like chimps, both fish use teamwork to hunt for prey. But while chimps hunt in troups for meat to supplement their diets, trout and grouper team up with moray eels in the hunt for food, each benefitting from the particular abilities of the other.
Using head shakes and handstands, the fish signal to eels the location of prey. The fish the moray eel fails to catch are sitting ducks for attack by the fast swimming trout, the fish the trout miss flee for crevices in the coral and rocks, that the moray eel can wriggle into. Both gain, but the fish are the brains of the operation, repeatedly choosing to do business with only the most successful hunters among the eels.
3 second memory = myth
Far from possessing the feeble three second memory attributed to the humble goldfish, new research shows that fish are perfectly capable of retaining information, not just for seconds, but for up to five months.
When scientists trained fish to associate certain sounds played through an underwater loudspeaker, with a particular action, like feeding, they were encouraged to discover that the fish would gather expecting food whenever they heard the noise. But they were amazed to observe that even months later, the fish remembered the sound, so that when it was played again, they gathered expecting fee grub.
What’s the time Mr. Fish?
Think fish are stupid? Think again, because it’s not just their intelligence and memory that make them cleverer than previously thought. Now, scientists from Plymouth University have proved your goldfish is so bright, it can even tell the time!
Fish were placed in a special bowl into which food was released only when the goldfish pressed a lever. The fish soon got used to food on request, but when the rules were changed so that food was only released once a day at a particular time, the fish quickly adapted. At dinner time, they clustered around the feeding point, ready to press the lever.
If that isn’t amazing enough, if the researchers chose not to release the food at the appointed time, after an hour, the fish gave up pressing the lever, proving they’re capable of understanding that time was up.
Now you’re talking
What sort of sound does a fish make? For a long time, scientists thought fish were dumb creatures who couldn’t communicate with each other. But now, research shows that fish live in complex societies, enjoy the company of other fish and use pops, clicks, grunts, and displays to communicate a wide range of thoughts and emotions.
Researchers in New Zealand used microphones and motion detectors to listen in on tanks of fish. They were stunned to discover that some fish kept up a continual chatter. It’s thought the sounds fish make by twanging their swim bladders are used to alert other fish to danger, point to food sources, attract a mate, and are even a way of orientating themselves around reefs. Of the fish studied, gurnard were the most chatty with cod being the strong silent types, only getting vocal around breeding time!
Walk the walk
Fish can do more than “talk the talk”, it appears they can “walk the walk” too! It’s called “developmental plasticity” and fish have it. Researchers know that 400 million years ago, in the Devonian period, fish adapted to survive on land, eventually becoming land dwelling creatures; our earliest ancestors. But scientists wanted to see what would happen if they took a modern polypterus, an African fish that has lungs, and forced it to remain largely on terra firma. The results were stunning.
In under a year, the fish learned to use its fins to ‘walk’ effectively, bringing its fins closer to the midline of its body, raising its head higher and even learning not to slip and slide in the mud. And crucially for scientists studying evolutionary biology, their shoulder joints and spine adapted to the task of carrying the fish’s body on land, demonstrating the likely process through which the switch from sea to land was made.