Clownfish can find their way back to their reef using their sense of smell
After clownfish hatch from their eggs, they spend about 10-12 days floating freely in the ocean, as pelagic larvae. After that time, they often return to the reefs close to shore, where they were born. The mechanism through which the fish find their way back home after drifting at sea among the plankton has long been a mystery to scientists. Based on a study published in The Proceedings of the Royal Society B, scientists believe that the clownfish may use their sense of smell to find their way back to their home reef.
In the waters off New Guinea, Percula Clownfish, Amphiprion percula, inhabit shallow water reefs under the canopy of the New Guinea rainforest. The scientists demonstrated that the clownfish, when presented with the option to swim towards water that was treated with anemones or leaf litter from their home reef or to swim towards control water samples, preferred the water that contained scents from their home reefs.
While olfactor sensation (sense of smell) has been an acceptable theory of how migratory fish find their way home, terrestrial causes of scent, like rainforest leaf litter have only recently been considered. The scientists also demonstrated that even laboratory raised clownfish shared the preference of swimming towards the scented water, suggesting that chemical or olfactory signals in the water may hold the key to how fish like the Percula Clownfish, Amphiprion percula, navigate in the open ocean.
This blog post is based on an article that was originally published in Aquarium Fish International, February 2009: page 18
I picked the photo above because it looks to me like the clownfish are enjoying the smell of their host anemone. Of course, I’m totally projecting that emotion on them. The photo was available on Flickr with a creative commons license and was originally taken by malfet_.
Check out the following links for more information:
Choi, Charles, B. “Scientists Learn How Nemo Finds His Way Home”. August 26, 2008.
Dixon, et al. “Coral reef fish smell leaves to find island homes”. Proceedings of the Royal Society B. Published online: July 2008.