By Blaise Jones
Time and time again it has been said that sharks are unfairly labeled as mindless eating machines. Previous articles have discussed how sharks are actually careful hunters that selectively choose their prey, a far cry from the popular image of mindless eating machines sharks have. But if sharks aren’t just eating machines, this raises a question: just how smart are sharks?
Testing Shark Smarts
Before the question of shark intelligence can be answered, we first have to know how intelligence in animals is determined. After all, scientists can’t just have a conversation with a shark. There are two sources scientists use to determine animals intelligence: brain size and learning ability.
Big Brains for Biting Benthic Behemoths
Brain size is simply a measure of the size of an animal’s brain in proportion to its overall body size. The higher the percentage, the smarter the animal generally is. For example, humans have a brain:body ration of 1:50. The average shark has a brain:body ratio of between 1:500 to 1:1,000, making their brains larger than about a one-third of birds and mammal species, and larger than all the bony fish.
However, it should be noted that much of a shark’s brain is made up of areas dedicated to processing sensory data. The sections associated with learning are smaller in comparison.
Teaching an Old Dogfish New Tricks
While their brains may be more dedicated to processing sensory data, sharks are by no means slow learners. Experiments done on certain shark species show that they can learn to associate certain stimuli with either food rewards or discomfort in 10 sessions or fewer .
Sharks have been trained to associate certain sounds, lights patterns, and even shapes with food, and have been trained to be hand-fed food from only one person when presented with different options. One test presented sharks with multiple buttons and bell sounds. When the right sound was tolled, and the right button pressed, the sharks would be rewarded with food. Soon the sharks involved with the test were able to hit the right button at when the right sound was tolled every time.
This learning behavior is not just isolated to the lab, however. Wild sharks have been observed displaying new behaviors in an effort to get an easy meal. Many spear fishers have reported being harassed by smaller sharks, which do so to get the spear fishers to drop their catch. Many dive tours use wild sharks that run on feeding schedules as a way to help predict the presence of sharks for their tourists and enhance their experience. The sharks have learned that at a certain time of day divers show up at a certain location and feed them.
Great White Smarty Pants
Out of all the sharks out there, none have captured the public’s imagination as much as the great white shark. Therefore it’s no surprise that there has been extensive behavioral research on great white sharks, and what researchers have found has been nothing less than astonishing.
Great white sharks have been observed to have a complex hierarchy, with display and dominance behaviors, as well as other more seemingly playful interactions. Great white sharks have also proven to be extremely curious animals. In many cases great whites will forgo feeding behavior in order to investigate novel objects in their environment.
An experiment was performed where scientists dropped two objects into the water with great whites. One was shaped like a seal, a common food source for great whites, while the other was a cube, which would be a shape totally alien to animals living in a marine environment. It was found that the sharks would ignore the seal-shaped object in favor of examining the cube, many not even biting it and instead bumping it and examining it.
A “Whale” Oiled Team
The strongest evidence of great white shark intelligence comes from an event that occurred in Smitswinkle Bay, South Africa, where seven great white sharks were observed attaching themselves to different sections of a dead pygmy southern right whale which was partially beached. Instead of immediately feeding on the exposed areas, theses sharks worked together to pull the dead whale into deeper water, where they could access the whole carcass.
“The Secret Life of Sharks” by Dr. A. Peter Klimley
“Sharks: The Animal Answer Guide” by Gene Helfman and George H. Burgess
“The Encyclopedia of Sharks” by Steve A. Parker