Chiamocleis ventriaculata: Living with the Enemy

Introduction: Chiamocleis ventriaculata is a species of frogs can be found in tropical and subtropical areas in swamps, lowlands, and forest, but this particular relationship has been studied specifically in South America and India. (1) While many times frogs are usually the prey of many species of spiders, some frog species have developed mechanism to avoid becoming a spider’s next meal.(2) The microhylids seem to discourage the spiders from eating them through the use of skin toxins.(2) Often time younger spiders have been observed pouncing on the frog when alerted to its presence in the burrow briefly before quickly releasing it from its mouth.(2) A particular spider species that most commonly forms this type of relationship is known as the theraphosid tarantula Xenesthis immanis commonly found in Peru and other South American countries.(1) Both the spider and frogs remain in the burrow until they come out to feed at night.(3) The Chiamocleis ventriaculata feed on ants and other small insects while the Xenesthis immanis feed on insects, small mammals, lizards, and reptiles. (3)
Description of the Relationship: The frog Chiamocleis ventriaculata is a member of the family Micorhylidae.(3) The relationship between the Chiamocleis ventriaculata and their spider housemates is a unique relationship. More often than not, larger spiders have been known to prey on frog similar to the small microhylid frog. (1) In fact many times these spiders have been known to very aggressive toward other animals even other species of spiders coming near their burrow.(1) The Xenesthis immanis is also known as the Columbian lesser black spider because of its origins in Colombia. (1)

Cost/ Benefit: This relationship has been classified as a commensalism relationship. The frog is given protection from the many larger species that prey upon it, and the spider does not attack because of the frog’s possible defense mechanism or simply does not see it as a threat. Recent studies have shown that this relationship might be better classified as cooperation. While the relationship is not obligatory for either species, there is some benefit for the spider. Chiamocleis ventriaculata that inhabit burrow have been shown to include ants as a larger part of their diet versus none burrowing frogs.(3) In return for safe housing, the frogs keep away ants that can be a potentially dangerous pest to the Xenesthis immanis.
References
1. Hambler, Keith, Cocroft, R. “Observations on a Commensal Relationship of the Microhylid frog Chiamocleis ventriaculata and the Burrowing Therasphosid Spider Xenesthis immanis in Southeastern Peru”. Biotropica. 21(1)2-8. 1989. Web. 1 April 2012. < http://www.biosci.missouri.edu/cocroft/Publications/RBC%20pubs/1989%20Cocroft%20Biotropica.pdf>
2. Siliwal, Manju , Ravichandran, B. “Commensalism in Microhylid frogs and mygalomorph spiders”. Zoo Print Magazine. Web. April 1 2012. < http://www.zoosprint.org/ZooPrintMagazine/2008/August/13.pdf>
3. Sluys, Schittini, Marra, Azevedo, Vicente, and Vrcibradic. “Body size, diet and endoparasites of the microhylid frog Chiasmocleis capixaba in an Atlantic Forest area of southern Bahia state, Brazil”. Brazilian Journal of Biology. vol.66 no.1a São Carlos Feb. 2006. Web. 1 April 2012. < http://www.scielo.br/scielo.php?pid=S1519-69842006000100021&script=sci_arttext>