Here's Something Fishy About This Week's Theme

Those PhotoHunters who have visited before may have noticed that I try to relate the weekly theme to the central subject of this blog which is the pond, its inhabitants and visitors, and the plant life and other creatures in the immediate vicinity around the pond. This week's theme of 'dark' presented a bit of a challenge as there aren't too many things around the pond that are dark. At least not ones which would make for interesting photographs.

A few days ago while feeding the fish it came to me. Now this one may require a bit of explanation, but here is the photo which was taken in the spring.


I know you are probably thinking 'OK. That is one big dark fish. What's the big deal?' Well, check out the bottom side or belly of the fish...


As you can see, it's not dark at all. In fact it is mostly white.Did you ever notice that the coloring of many fish follows this pattern? They are frequently dark on the top (back) and light on the bottom (belly). Well here is one reason for that.

The pattern provides a simple camouflage sometimes known as countershading. Many fish are the natural prey of other fish (and other predators) and they live in an environment where they can generally be attacked from any direction. If the predator is above them and looks down, then the fish more easily blends in with the dark colors of the deeper, darker water or the bottom. If the predator is below them and looks up then the fish tends to blend with brighter water and sky above. If the predator approaches from the side then the blend of light and dark tends to break the total silhouette against the background.


Interestingly this same camouflage can often provide the same benefit to the predator. If they are similarly marked when approaching from above or below they enjoy some of the same advantages making them less visible to their potential prey. Countershading as a camouflage is not restricted to fish. It can be found in other animals also, particularly birds.

By the way, for those who are wondering that is a catfish and a pretty good size one at that for such a small pond. And don't worry. Even though catfish is very tasty this one ended up being returned to the pond. Here you can see it rolling as it was put back in the water. In less than a minute it swam away. We frequently see a big catfish coming up in the shallow water and we think it may be the same one as it is unlikely there are many that size in the pond.



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