How smart is a dolphin, or a seal, or an otter for that matter? How can we test for animal intelligence? This week we delve into marine mammal intelligence: their learning abilities, self-awareness and tool use. Here we cover some of the highlights of that work.
When we think of intelligence in marine mammals, you probably look towards dolphins and their problem-solving abilities or performances in captivity. However, marine mammals show a vast array of behaviors exemplifying their high intelligence. Though rare in the animal kingdom and highly contested amongst researchers, the use of “tools” in marine mammals is seen in some select species. Though the term “tool” in our minds generally means an inanimate object we physically grasp to complete a task, some marine mammals can use objects similar to this ideal while also occasionally using the water medium itself.
Perhaps the most obvious and most widely seen use of tools in marine mammals is found in the sea otters. Ranging along the West Coast of North America all the way to Alaska, otters are commonly found using rocks for means of accessing prey encased in shells (they have entered the stone age!). With some of their prey consisting of hard-shelled bivalves (clams, mussels, etc.), sea otters have been seen floating on their backs and holding rocks to bash open shells to access the protected meat, known as the rock anvil method. Otters have also carried rocks during their dives to bash shelled organisms off the sea floor, using the rock as a hammer to pry off the organism or directly access the meat! In fact, some areas in California show 80% of living and dead abalone shells exhibit crack marks indicative of rock bashes from otters. Additionally, these intelligent animals will use kelp as a tool as well, either to wrap themselves or their pups to prevent drifting away in ocean currents, or to immobilize prey (particularly crabs) while they forage on others.
While otters are the most prominent example of tool use in marine mammals, we have seen others with different methodologies. Touched on more in a previous post (see Bottlenose Dolphin Foraging Strategies), a small population of bottlenose dolphins in Western Australia wrap their rostrums in sponges to act as a shield as they forage through the rugged ocean floor. Some dolphins in Florida will use mud to circle fish schools to act like a net for easier capture, while humpback whales will use a similar method by blowing a net of bubbles around a school of fish to easily gulp up the school in the middle – both tasks using the water medium as a tool!
With all these examples generally accepted as tool use in marine mammals, there are others that could be considered tool use as well. For example, some orca whales in Antarctica will swim in a way to create a wave to knock seals off ice flows – using the water itself as a tool. Male Amazon River dolphin commonly carry sticks or debris in their mouths for potential mate attractants, while many dolphin species continually play with plant material or other ocean debris, potentially strengthening social bonds. Our understanding of tool use and our actual definition of a tool may need to be expanded, as we generally compare the human to the many different livelihoods and brains of other species. We are only beginning to further understand animal intelligence and therefore marine mammal intelligence, and there is plenty more to find out with continuous observations and surprises.