Warts and toads. They go together like witches and Halloween. The warts are actually glands that can produce secretions which are often poisonous or at least bad tasting to potential toad predators. There are other frogs that are called toads because of their warty appearance but the true toads belong to the family Bufonidae.
World-wide, there are over five hundred species of bufonids. The proper name for a toad wart is a parotid gland. These poison glands occur on the back but the biggest ones are on the head behind the eyes. They share several important characteristics besides warts. All have pectoral or shoulder girdles that are not fused together. They have no maxillary teeth. Their digits have no discs or intercalary cartilages, but their toes are webbed. Toads are amphibians so they share many characteristics with frogs.
They have a tadpole stage that has gills and lives in water. Most toads, like frogs, lay eggs that hatch as tadpoles. However one group of toads produces eggs that hatch directly into small toads. The adults have short, fat bodies with long, bent hind legs and no tails.
All toads, like frogs, are predatory as adults, living mostly on insects and other invertebrates. Tadpoles can be either carnivorous or herbivorous. The most infamous toad is the cane toad, or Bufo marinus. It was introduced to Australia, which has no native bufonids, to eat the cane beetle. It couldn’t be bothered to do that since there were so many other tasty things to eat and it has spread across northern and eastern Australia, to the detriment of many native species, which were not used to poisonous prey. In addition, the cane toad tadpoles are predators of frog tadpoles so when they move into an area, the tadpoles kill off the next generation of frogs, while the adults kill anything that tries to eat them.
Other species of toads are not harmful, but important members of their ecosystems and food chains, serving as both predators and prey. Most toads live in tropical and subtropical zones in wet habitats. They are generally nocturnal, hiding during the day and coming out to feed and look for mates at night. There are a few toads that have adapted to drier environments like deserts. They do this by burrowing. Toads are found throughout Asia, Europe, Africa and the Americas. There are no toads or in fact any amphibians on the Antarctic continent. Toads may have poisonous glands but the secretions do not cause warts so you cannot get warts from handling toads.
For more information:
http://zipcodezoo.com/Key/Animalia/Bufonidae_Family.asp
http://www.fs.fed.us/r4/amphibians/family_bufonidae.htm
