Scat

Can you see the present that our Grey Tree Frog left behind? This branch has been his favorite place to leave his scat lately. 😝

I felt compelled to share more educational information with this scat photo, so I broke out my "Animal Physiology" textbook from college. I was fascinated to find that amphibians produce waste differently between their tadpole and adult forms. If you are prepared to dive into the science of amphibian waste excretion, keep reading!

All animals produce waste products when converting food into energy. Carbon dioxide is one byproduct that is easily expelled through lungs or gills. Water created in this reaction simply becomes part of the animal's body. The third type of byproduct is nitrogen, which is more difficult to get rid of.

There are several ways animals get rid of waste nitrogen. The most primitive way is by excreting ammonia. Ammonia doesn't require energy to produce, but it is highly toxic. It may save the animal energy, but has to be released constantly to avoid poisoning the animal itself. Many aquatic animals - including amphibians during their aquatic tadpole phase - use this method since the ammonia can be quickly released into the water through gills.

Now imagine a tadpole turning into a terrestrial frog. On land, ammonia excretion requires a ton of water. That doesn't sound too appealing for an amphibian that now needs to stay moist on land.

Instead, the adult frog begins excreting urea, a different type of waste nitrogen molecule. Urea costs energy to produce, but it is less toxic and needs less water to be expelled.

A frog's physical transformation from tadpole to adult is amazing. But it is fascinating to realize that even systems within the frog's body - like waste management - need to change to adapt to their new terrestrial lifestyle. In different habitats, they need to adjust to different costs and benefits of the ways their bodies work.