American Toad (Bufo americanus)



     Bufo americanus’ are nocturnal.  This is an important adaptation because they are less susceptible to being ingested by predators if they are in the dark.  However, they are more vulnerable to being run over by cars or bicycles at night. Being nocturnal has generally helped the species adapt to its environment. They are also semi-camouflaged.  Their varying colors help them blend in with their environment. The toad moves via extending its hind legs; however, since they are relatively short, the toad has a weak ability to jump high. 

         To aid in protection from predators, the toad secretes bufotoxins from the two paratoid glands located behind each ear (the circular structure behind each eye).  This milky toxin is used to ward off predators because of its vile odor and taste.  The secretion can even cause some predators distress if ingested, for example dogs. Another defense against predators is seen when the female lays her eggs.  Once the female toad releases them, the eggs are exposed to the harms of the water, including toxins and predators, like fish.  For this reason, the female frogs have adapted to finding ephemeral ponds (those that do not hold water year-round).  These ponds do not have fish and, therefore, the risk is reduced of these developing eggs being eaten by fish.

         Because the toad has highly permeable skin, chemicals in the soil (pesticides and heavy metals) can penetrate the skin and enter the toad’s body.  However, the American Toad has yet to adapt a way to decrease accumulation of harmful chemicals in its body.  Due to increasing pesticide levels, the toad populations are decreasing in many areas.   


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