As I sit on my tour boat at my pontoon I often take in the scenery that most of us overlook, but which is taken in awe by visitors. Apart from the scenery, one of my great joys is showing my guests the ever present archerfish waiting for its token of a little bit of bread which they jostle for. They are not overfed and I feel that they enjoy the playtime. I once tried to tease them with pellets which are prepared for barramundi food; they don’t like it! They don’t even jostle for it but ignore it as it projects through the air! They can actually classify what is being offered to them which obviously means that they have fantastic eyesight. In case you don’t know what an archerfish is, it is a silvery fish, growing to be about 30cm long and it has dark grey spots on its sides. I guess that they are good eating. Its significance is that it has evolved with a hunting technique that is probably unique; the ability to shoot down a nearby insect with deadly accuracy with a fine jet or gush of water through its mouth. Some years ago, one of our guides gradually teased and trained them to shoot a jet of water at tourists’ faces as they leaned over the side to get a better look, they will forever remember their Daintree tour! These fish don’t necessarily have this playground to themselves. They are challenged by the catfish.

Just recently, I read an article in a newspaper written by Narelle Towle, about these amazing archerfish, and its secret weapon. She says that biologists have discovered that the fish’s eyes have evolved to ‘tune’ in different ways. It can clearly focus on objects above the water while watching below, giving it a clear advantage over other fish. They can also overcome the problems of refraction (it is like shining a torchlight into the water, you’ll notice that the light beam is ‘bent’). They say that the “archerfish have differentially tuned their rods and cones across the retina to suit the spectral of differences of seeing in and out of the water”. In other words the light refracted is not evident to them. That’s one smart fish! See you next month.

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