New Research on the Behavior of Tarantulas with Other Species

Researchers identified a possible explanation for the hairy nature of tarantulas and also described cohabitation of tarantulas with many other species in their environment.

The article appears at An extensive review of mutualistic and similar ecological associations involving tarantulas (Araneae: Theraphosidae), with a new hypothesis on the evolution of their hirsuteness.

Mutually Beneficial Cohabitation of Tarantulas

Snakes

Tarantulas are generally not an animal that people believe co-exist with other animals in their environment. The researchers describe non-antagonistic behavior of animals interacting with several species including snakes.

The first case was observed in Guerrero State of Mexico by the second author. While turning over large angular rocks lying on the ground in search of theraphosids, one rock was turned to expose the burrow of a large female Brachypelma boehmei Schmidt and Klaas, 1993 (Theraphosinae) standing mere centimetres away from a coiled Michoacán ground snake, Sonora michoacanensis (Duges, 1884) (Colubridae). No predation attempt was made by the tarantula on the snake.

Brachypelma Boehmei should be recognized as a commonly kept species of tarantula in the pet trade. Adult individuals can reach 6 inches while the snake it was found near reaches a known length of about 12 inches.

Tarantula species are known to prey on vertebrates including snakes however this description of the two species cohabiting without antagonizing each other suggests a possibly beneficial relationship.

In the Frogs section of this article another interaction with frogs and tarantulas was observed.

Ants

The researchers propose that tarantulas are able to coexist with aggressive ants because of their urticating setae ("hair") similar to species of caterpillars with similar structures.

Herein, we propose an alternative hypothesis supported by observations and field experiments: the hirsuteness of theraphosids, particularly those of Theraphosinae, could have evolved partially as a defensive strategy against army ants. In April 1996, these findings were shared with Edward O. Wilson, the late world-renowned ant specialist from Harvard University, who agreed with the hypothesis. Indeed, many invertebrates have evolved characteristic hairs, spines or similar structures on their bodies or appendages in response to evolutionary pressures from their predators.

Frogs

Frogs are a commonly known animal that coexists with tarantulas. A frog could be easily dispatched and consumed by a tarantula yet many tarantulas are found near frogs without displaying predation. Below, an early researcher held an experiment where a Great Plains Narrow Mouthed Toad (Gastrophryne Olivacea) was placed in a terrarium with a Texas Brown Tarantula (Aphonopelma Hentzi) and no predation was observed while the introduction of a snake caused the tarantula to immediately attack the snake to the benefit of the frogs.

Hunt (Citation1980) conducted an experiment to test the tolerance of G. olivacea by A. hentzi in a terrarium. The spider did not attack the frogs, as expected. In the same environment, when a snake – a natural predator of G. olivacea – was introduced, the tarantula swiftly attacked the snake after the frogs sought shelter in its burrow.

This cohabitation between the species has been a discussion among hobbyists and field researchers for quite some time, contributing to the researchers inclusion of this relationship in the new research paper.

Conclusion

The article described many scenarios where tarantulas were present near other animals and neither animal was antagonistic. In the case of ants, it appeared that the "hairness" of tarantulas might prevent predation on the tarantula by the ants. Keepers will be familiar with finding these hairs in molting mats which can also explain why the tarantulas aren't consumed by the ants while they are in a delicate molting phase.