This tarantula keeps a small frog as a "pet" to eat insects that eat the spider's eggs (Twitter)

[zuul]

Link to tweet

https://scienceblogs.com/tetrapodzoology/2009/07/03/tiny-frogs-and-giant-spiders?utm_content=buffer2b6f1&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

The recent discovery that some Asian microhylid frogs frequent the dung piles of elephants has gotten these obscure little anurans into the news, possibly for the first time ever. Microhylids - or narrow-mouthed frogs - are not exactly the superstars of the frog world: they're only really familiar to specialists, despite the fact that (as of June 2009) they contain over 450 species distributed across Africa, Madagascar, the Americas, and Asia. However, some more recent research on the group shows that, like so many animals, they're really quite interesting once you get to know them...

You might be surprised to learn that microhylids in Peru, India, Sri Lanka and perhaps elsewhere have developed close relationships with large spiders. One of the first published discussions of this phenomenon was produced by Crocraft & Hambler (1989). Noting a close association between individuals of the Dotted humming frog Chiasmocleis ventrimaculata and the burrowing theraphosid tarantula Xenesthis immanis in southeastern Peru (but read on), they suggested that the spider - well capable of killing and eating a frog of this size - used chemical cues to recognise the frogs. Young spiders have sometimes been observed to grab the frogs, examine them with their mouthparts, and then release them unharmed. Microhylids are probably unpalatable due to their skin toxins, and this might explain how this association arose in the first place [the image above shows a tarantula walking over a Dotted humming frog. Photo by Emanuele Biggi from here on Anura.it. Used with permission].

Crocraft & Hambler (1989) noted that the frog seemed to benefit from living in proximity to the spider by eating the small invertebrates that were attracted to prey remains left by the spider. The frog presumably also benefits by receiving protection: small frogs like this are preyed on by snakes and large arthropods, yet this frog is protected by a formidable spider bodyguard. Hunt (1980) suggested that the spider might gain benefit from the presence of the frog: microhylids specialise on eating ants, and ants are one of the major predators of spider eggs. By eating ants, the microhylids might help protect the spider's eggs.