Good mood today for some caecilian factoids:

The poison of the golden dart frog (Phylobates terriblis), an alkaloid Batrachotoxin, is potent enough to kill 100 adult humans if it enters the bloodstream or is consumed.

The secretion from the Ecuadorian species Epipedobates tricolor has been adapted to create a pain killer called ABT-594 “epibatidine”, which is 200 times more potent than morphine. Its toxins is one of the most venomous among all frogs.

The cane toad, one of the more well-known 'psychoactive toads', secretes bufotoxins in small quantities from its skin. Bufotenin, a type of bufotoxin, is classified as a Class 1 drug alongside heroin and cannabis under the Australian law.

The Colorado River toad (Bufo alverius) however, is the only psychoactive toad species known so far to secrete both bufotoxin and 5-Me-O-DMT (a powerful psychedelic substance) in its skin and venom. The compound is extremely hallucinogen when vaporized by heat and inhaled in the form of smoke. An adequate dose for a normal, average-size adult is of the size of a match head.

Abnormal limb growth (ectromelia: missing limbs and ectrodactyly: extra limbs) is observable in frogs which had the parasitic flatworm Riberoria trematodes burrow into areas of the tadpole where limbs are developing. Cysts formed around the parasite can damage or disrupt normal limb development. Other hypotheses for this limb malformation phenomena of amphibian malformation include increased UV radiation (due to ozone thinning), exposure to high levels of nitrogenous fertilizers (runoffs from agricultural lands), attempted predation and cannibalism.

Antimicrobial peptides from frog or toad skin has been observed to inhibit HIV infection.The Australian red-eyed tree frog, Litoria chloris, has the highest levels of peptides. Source: Science Daily: Frog Peptides Block HIV in Lab Study

The Borneon Flat-Headed Frog is the only frog species known to be entirely lungless, fully depending on respiration through its skin. 

Lancelot Hogben developed the Bufo test (named after the toad species used, Bufo arerarum). It is a pregnancy test where a female frog is injected with the serum or urine of the patient. If the frog produces eggs in the next 24 hours, the patient is deemed pregnant. Similarly in the cane toad, injecting urine laden with hCG into the lymph glands of the male toad induces production of spermatozoa.






Additional links:
Discovery of the Purple Frog: Living Fossil (BBC News)