Where did that expression “like shooting fish in a barrel” come from? Meaning it’s so easy, you can’t miss? Well, you can’t really miss when you take photos of tree frogs in a rain barrel either, except when you have absolutely no room to get behind the camera viewer and have to hold it over your head and point randomly downward hoping the subject is in the photo, like this.
Gray Tree Frogs hang around landscaped dwellings in the summer after they breed in the nearest pond. They especially like outdoor lights…and rain barrels, where they find lots of tasty insects to eat. They climb vertical surfaces with ease using those super-sticky toe pads.
(Photo from Hanna and Barnes, 1991, Journal of Experimental Biology 155: 109)
However, there is no glue or adhesive secreted, just the simple physics of the surface tension developed by a large area of moist skin pressed against a flat surface. It’s the same principle used for suction cups that stick to vertical glass surfaces. For greater sticking power, frogs press their belly and thigh skin against the surface as well, and can stay put at angles of as much as 150 degrees from horizontal (i.e., tending towards upside down). Read more about how this was determined here.
(Photo by co-blogger Alison)