Breathing. There are two ways a frog can breathe. The first is by lungs and the respiratory system. The frog breathes through its mouth, the air is taken into the lungs. Frogs also have a nose which is placed on top of the head in front of the eyes. The nose is located there so the frog can breathe even when it is mostly submerged in water. Plus, frogs use their nose to smell—yes, I said it, smell. They use their smell as part of their reproductive strategy.
The second way to breathe is through the skin which is highly permeable. Especially, over the “rump”, the spot they sit on. This spot has a very thin layer of skin in order to better absorb ground moisture. Frog skin needs to be able to allow the exchange of water and gases across it, because it is how the frog does most of its breathing. It also allows the frog to maintain its electrolyte and water balance in its body and with its outside environment. A frog sheds its skin every so often. This is exuviation. First, the limbs come out, then the rest is wriggled off and pulled over the head and eaten to help prevent added salt and nutrient loss. But now I’m starting to get side tracked. So, the skin allows gas exchange through the skin by all the many, tiny blood vessels connected to it that pick the oxygen from the water and bring it directly into the blood stream.
The blood stream—the circulatory system. The basic components of the frog circulatory system are like humans. Blood starts at the heart –> arteries —> capillaries —> veins —> heart. It’s a continuous chain. And, the blood carries necessary nutrients and gases throughout the body.
Once all the nutrients and use is taken out of an energy source the wastes are brought to the excretory system. From the digestive system the wastes travel out the hind gut and cloaca, which is located at the anus, more commonly referred to as the vent. From the blood stream, the circulatory system attaches/comes in contact with the kidney. The kidney filters out excess water and wastes, which are taken to the urinary bladder then also released through the cloaca. Since frogs need to keep their osmotic balance though, (the movement of water across the cell membrane), they excrete a minimum amount of salt and up to one third of their body weight in water.
There are a few other organs frogs have that I didn’t get to mention yet. One is the lateral-line organ. This is in tadpoles and some frogs. What it does is detects water movement through vibrations. Another is the statoacoustic organ system, made up of folded tissue and lymphatic fluid, it gives the frog its sense of balance and aids in hearing. Third is the lymph system which is well-developed.
Works Cited:
Behler, J. L., & Behler, D. A. (2005). Frogs: A chorus of colors. New York, NY: Sterling Publishing Co., Inc.
Beltz, E. (2005). Frogs: inside their remarkable world. Buffalo, NY: Firefly Books Ltd.
Forsyth, A. (2008). Nature of the rainforest: Costa Rica and beyond. Ithaca, New York: Cornell University Press.
Photo taken by Caty Jones
Two wood frogs
Spring 2008
Mongabay.com
Rhett A. Butler - San Francisco, CA.
1999-2008.