By Francesco Tomasinelli

Last update 20/12/2008

Early explorers back from south american rainforest reported of huge spiders killing birds and weren’t believed. Further investigations confirmed these incredible predations do occur and impressive drawings were painted, featuring big tarantulas feeding on defenceless hot-blood animals.
Recent studies taken in Brasil (Toledo and others) state that big predatory Arthropods, especially spiders, are among the most important threat for small Amphibians in rainforests. Cupiennius wandering spiders are guided by vibrations emitted by male singing tree frogs, while big tarantulas Theraphosa attack small gecko, lizard and sometimes rodents on forest floor. But there are reports of small snakes, including rattlesnakes, being killed too. On the contrary, sometimes, tarantulas and frogs build strong positive relations, with the spider (Pamphobeteus) not attacking the frog (Chiasmocleis) in close proximity and inside his burrow, since the small amphibian can elimante parasites near spider’s nest. See a very detailed report here.
Other surprising predators like fishing spiders Ancylometesand Dolomedes can take fishes and tadpoles directly in the water performing a sudden dive. The nasty tropical centipedes and solifugids (camel spiders or wind spiders) seems to consider many small reptiles as tasty as insects.
Praying mantids are among the most aggressive carnivorous insects. So it’s no surprise if, according to various observations, a part of the diet of the biggest species is composed of vertebrates. There are even reports of hummingbird being attacked. In the tropics the huge, nomad echelons of army ants (Eciton) and driver ants (Dorylus) can kill any small prey not fast enough to run away, including reptiles and amphibians.
Surprisingly such behaviour are not limited to tropical countries. In Europe mantids take small lizards basking in the sun and scolopendras hunt them under rocks at night. In France a predatory bush criket Saga pedo has been seen while consuming a lizard. In ponds and streams the raft spider Dolomedes fimbriatuscatches small fishes, and the poorly known freshwater crab Potamon fluviatile is known to prey on frogs too.

Many thanks to Sara Fratini, Fabio De Vita, Emanuele Biggi, Emilio Scoti for precious informations and help.