5 Aquatic Animals You Didn’t Know Use Tools
Oh my God. Something terrifying has been discovered. Crocodiles and alligators use tools to hunt. The world is clearly coming to an end. Excuse me while I move down to my bunker.
Mugger crocodiles and American alligators lie partially submerged under egret and heron colonies with sticks balanced on their noses. When the birds go down to collect the sticks for nests…CHOMP. Researchers believe this is an example of tool use and not just a happy accident because floating sticks are rare in the pools they looked at and sticks that are around are quickly snatched up by the birds for nests. According to Scientific American:
The possibility that stick-displaying behaviour results from a random association between rookery-frequenting crocodylians and floating sticks was deemed unlikely by the authors, since floating sticks are extremely rare in the pools concerned, especially at the time of year concerned (partly this is because the local trees – baldcypresses and water tupelos – don’t shed twigs, but also because the nesting birds rapidly remove floating sticks for nest-building). Therefore, deliberate collection and employment of sticks by the crocodylians seems most likely…: it seems that they are practising baiting behaviour, whereby predators use objects in order to get potential prey to closely approach and hence become easier to catch. Even better, they are seemingly only practicing this baiting behaviour during a specific part of the year.
Whoa. Primates and some birds are famous for their tool use, and now I guess we can add crocodylians to the list. There are a lot of animals you might not expect that use tools to get food, to defend themselves and for grooming, recreation or construction. In fact, more of these animals are aquatic than you might think.
You don’t normally think of an octopus having a home. I mean, the ocean is its home, right? That’s not enough for the Veined Octopus. It’s been seen collecting old coconut shells, stacking them, moving them up to 20 meters, and then assembling them into a shelter. If they find two halves, the octopus will close themselves in. If they only find one half, they will flip the shell over and hide underneath. This behavior was caught on video between 1998 and 2009.
What? A fish? I’m as surprised as you are, but it’s true. The fish was caught on video digging up a clam with its little fins, carrying it over to a rock, and bashing the clam open. OK, it’s not sophisticated tool use, but what do you want? It’s a fish! This type of behavior has been spotted in other fish, as well.
This is an ant that I wouldn’t want to get on the wrong side of. This ant has a bit of a rivalry with another genus of ant called Myrmecocystus. The two have an overlapping region and food source, so what’s an arthropod to do? The Myrmecocystus ants have a gland that secretes poison that they spray all over their food so no other ants steal it. Conomyrma bicolor is a bit more clever. They have been observed dropping small stones and other objects into the entrance of their rival’s nest in an attempt to trap the Myrmecocystus inside, hence eliminating the competition for food.
We knew dolphins were smart, but they are also on the list of tool-using animals. It seems that some particularly clever dolphins in Australia’s Shark Bay have been trapping fish in conch shells and dumping the fish into their mouths. The behavior has only been seen a few times between 1996 and 2007. It’s not terribly common and seems to be a new innovation that takes some skill and practice. It’s unclear how the shell is used underwater. It’s hypothesized that fish swim into the shell as they are being chased, or the dolphins may use the shell like a net to catch the fish.
Photo Credit: Ianaré Sévi via Wikimedia Commons