Scientists recently discovered that two species of frogs have bony spines on their heads to deliver venom. Many frogs were known to secret poisons from their skin, but none were known to be venomous. Venomous creatures differ from poisonous creatures in that they need to bite, sting, or stab you to do their damage. Poisonous creatures have to be touched or bitten to employ their defense.

Scientists from Instituto Butantan in São Paulo, Brazil discovered the venomous frogs when faculty member Carlos Jared got injured accidentally touching the spiny head of the frog. The poison caused "intense, radiating pain for a period of about five hours."

Luckily, he touched the less venomous of the two species, Corythomantis greeningi. Had he touched the more toxic frog, Aparasphenodon brunoi, he would have been subject to venom 25 times deadlier than the venom of a pit viper.

Facts about venomous and poisonous creatures:

 These Brazilian frogs aren't the only venomous amphibians. Iberian ribbed newts can push out their own ribs when they are attacked. Spikes on the ends of their ribs jab predators with toxin.

 Poisonous frogs (and poisonous organisms in general) line their skin or other bodily surfaces with toxic chemicals that are either brewed from scratch within their bodies or acquired through diet. For example, cane toads make their poison in the glands behind their ears. Poison dart frogs, on the other hand, generate a highly poisonous alkaloid skin coating that they make from eating ants. If you take a young poisonous dart frog out of its natural habitat where it can't eat ants, it will naturally lose toxicity.

 Cover image: Carlos Jared/Butantan Institute via Live Science