There has been an ongoing debate in science as to whether or not animals have culture for well over a century. Now when I say culture here, I am not talking of sophisticated manners. Instead, I am speaking of unique behaviors taught or learned within specific groups. Intelligence in nature it would seem, is a subject that many are a bit uncomfortable with. If we have always defined what makes us human as our intelligence and our culture, than what does it mean if we recognize that other animals have not only extraordinary problem solving capabilities, but culture as well? Such a question is probably better left for another blog on the web of course. But this is very relevant when we are learning and teaching about Tursiops truncatas, or the bottlenose dolphin.
In the wild, there is a constantly evolving dance between predator and prey – each in evolutionary motion trying to stay one step ahead of the other. As a predator adapts in ways to advantage itself, those prey, if they are to survive, adapt in turn either physically or behaviorally in new ways to elude the would be predators.
Fish have evolved a unique line of sensory organs that we call lateral lines. That black stripe down the side of a largemouth bass is just that – a lateral line. All fish have it, even sharks. What the lateral line does, is pick up on the low electric impulses in the water that is produced through movement. By being able to read such minute electricity, fish are able to coordinate their movements with one another, or in response to the movements of predators in the area.
So think bait ball here. You have seen these on television before, that massive ball of innumerable fish magically splitting apart and coming back together again as predators attempt to dash through. With so many fish, so tightly packed together, it would seem like an easy meal. Yet rarely does such attacks prove successful. These fish operate like one giant living breathing organism responding instantly in coordinated movements. Watching this is truly one of the most beautiful sites to behold in ocean.
Predators, such as the bottlenose dolphin, have to adapt to such defensive mechanism in order to survive. And it is here, with the feeding adaptations that we find ourselves catapulted headlong into the sticky debate of culture.
Dolphins, like the rest of the world’s most intelligent creatures, live a highly structured social life. It is this social nexus that they must navigate that many biologists believe is the basis for evolving such a powerful brain to begin with. Since dolphins, like humans and chimpanzees, live and communicate with a structured society, these species (though not the only ones) are in the position to pass along information to one another. This may be through direct communication, or it could simply be through watching and learning.
Whichever the case may be, we know that certain populations of dolphins utilize very distinct and inventive ways to hunt – most often cooperatively – much like certain groups of chimpanzees. Take the dolphins of Shark Bay, Australia for example. In Shark Bay, and only in Shark Bay, bottlenose dolphins have taken to placing marine sponges on their faces when foraging for food along the bottom. There are a number of toxic creatures that dwell along the bottom of this bay, as well as razor sharp rocks. Its believed that either these sponges helped them stir up food, or otherwise protect them while foraging.
Jump to the other side of the globe and splash down into the waters of Florida Bay and you will find a completely different sort of cultural event taking place. Here, dolphins will employ the technique of mud rings to capture fish. One dolphin will swim around a school of fish, slamming his fluke (tail) down as hard as possible with each kick. This stirs up a thick cloud of mud and silt. As the dolphin circles the school of fish, he / she creates a ring of this thick cloud around them. As the fish begin to panic, the other dolphins line up around the outside of the ring to catch the fish as they attempt to jump over the cloud of mud.
A couple states north and we come to South Carolina, where dolphins have learned a unique method to capture food that researchers have termed “strand feeding.” Here in the salt marsh creeks, several dolphins will rush a school of fish so quickly that the wake generated by the back and dorsal fin of the dolphin actually picks up the fish and throws them onto dry land. The dolphins then race in, and slide up the bank out of the water, temporarily stranding themselves, to grab the fish left high and dry. Interestingly, these dolphins only ever strand on their right sides.
All three of these feeding behaviors are found in no other populations / locations on Earth. So what does this mean? Dolphins, like humans, are looking for new and better ways of solving problems in life. They experiment. They adapt. Through trial and error, they invent. Are dolphins teaching each other these successes? Many would argue no, that instead others watch the success and simply mimic it. Without this information being deliberately passed on however, how do you explain the coordinated efforts that make hunting techniques like strand feeding possible?
What is really intriguing though is that these distinct feeding behaviors have been documented in some of the most well studied populations of dolphins around. What of those groups that are not so well studied? What secrets about their culture do they harbor?
Dolphin Strand Feeding
mud ring feeding
