American Toad (Bufo americanus)


     The American toad is notorious for hybridizing.  A study shows that the toad commonly breeds with Bufo woodhousii, Bufo fowleri, and Bufo terrestris. Because it breeds with varying species, confusion might arise when trying to classify a toad.  The most common misconception is between the American Toad and Fowler’s Toad.  Here are some tips for accurately identifying both species:
               American Toad                                                                                            Fowler’s Toad
-  Can tolerate colder temperatures                                                             -  Easily limited by cold temperatures
-  Early breeding season (February)                                                           -  Breeds later in the season (May)
-  Paratoid glands do not touch the cranial ridges behind the eye                  -  Paratoid glands touch cranial crests
-  Prefer forest habitats                                                                              -  Prefer open, sandy habitats
-  Tend to have spotted bellies                                                                    -  Bellies are mostly clear, little blotching
-  1-2 warts on large black spots on back                                                    -  3 or more warts in each black spot

 *From the below pictures, you can clearly see the paratoid glands (the large pillow like protrusions) behind the eyes.  The cranial crest lies right behind the eye.  The American Toad on the left has separation between the gland and crest, unlike the Fowler’s Toad on the right.  Also notice the amount of warts in each black spot on the back.  The American Toad tends to have 2, while the Fowler’s Toad has 3 or more per spot.

     The bufotoxins produced in the paratoid glands are toxic to dogs in particular.  They cause irritation of the stomach and they learn quickly to stay away from the toad.  The toxin does not kill the dog; however, leaves it sick for about a week.  To learn more visit this website on Dogs.  The milky secretions from the glands are cardiotoxic steroids.  If ingested in large amounts, this toxin can cause cardiac arrest and even death.  Although the American toad does not possess a high concentrated secretion, its relative, the Cane Toad (Bufo marinus) does.  It kills humans, dogs, alligators and many other impressive vertebrates.  Click on Cane Toads to learn more about them on Multiple Organisms.

     Although the toxin will generally not harm a human if ingested, it will cause irritation of the skin and eyes.  Make sure to wash your hands before you touch your face if you have been handling an American Toad. If you are interested in learning more about poisonous creatures, visit other organisms on, for example the Japanese Pufferfish.

     The American toad has a number of parasites, both internal and external.  They include protozoans (Toxoplasma), helminthes, euglenozoans (Trypanosoma fallisi), nematodes, apicomplexans, trematodes, and cestodes.  To learn more about cestodes, visit this website about the Pork Tapeworm, one of the many species in the class cestoda.  Blood parasitism is one of the more widespread parasites, called Trypanosomiasis. Below is Trypanosoma on the left and a trematode on the right, two of the major parasites of the toad.


                                  If you forgot to look, visit the Adaptations page to see how these toads have adapted to their environment!