Tarantulas avoid incest during courtship
The reproductive habits of the Theraphosidae tarantula species, the oldest tarantula family in the Americas, are now being studied by Fernando Pérez-Miles, an Uruguayan biologist.Bogotá D. C., 20 de junio de 2012 — Agencia de Noticias UN-
The scientist, who was invited by the UN Natural Sciences Institute (ICN, for its Spanish acronym) for Thursday’s Biodiversity presentations, spoke about the main biological characteristics of tarantulas, with examples of species from the Southern Cone. He also provided some guidelines for tarantula recognition.
“This genus is diverse and numerous, with around 1,000 species. Half of which live in the Americas, however little is known about them from a biological standpoint. They are from one of the oldest families at more than 35 million years old. The largest member of the family measures around 20 centimeters and they live in caves, in holes or under rocks”, says the researcher.
With respect to its reproductive habits, which includes courtship, copulation and descendant follow-up, the expert indicated that reproduction is the most vulnerable state for the animal due to the risks taken and high energy expenditure.
During this process a couple of problems arise. First, the meeting of the two sexes must occur at just the perfect time and place. Secondly, courtship occurs based upon pheromones and other chemical signals.
In addition, tarantulas must be of the same species or else copulation will most likely fail. Finally they must avoid incest. Regarding the latter, they have a very precise mechanism for kinship recognition, including smell recognition of their own litter, recognizing different ages and maturity levels, and attraction to opposites.
“The last thing they want is to fail to perpetuate the species. Therefore, they must be capable of recognizing each other, despite living alone for most of their lives. In order to achieve this, they have a complex vibrating signal (seismic) communication system, transmitted through the ground, and tactile reception which allows them to recognize members of their own species. In this manner, they ensure successful copulation and progeny”, says Pérez-Miles.
The presentation, aided by photos taken during research projects performed in Argentina, Brazil and Uruguay (with the participation of Professor Pérez-Miles), highlighted aspects of the group’s evolution and explained a great deal about certain species in the region, such as Eupalaestrus weijenberghi and Acanthoscurria suina.
The researcher also spoke about their defensive behavior, characterized by the use of stinging hairs which they can both launch at enemies or apply through contact as well as the tarantula’s cave building techniques. He also noted that the spiders do not have many known predators, except for some wasps, and that they’re not an easy target for predators.
Finally the expert says that these spiders are very interesting biological models given their size and ability to withstand laboratory conditions. Therefore, many individuals can be bred in a relatively small space, which allows for testing different hypotheses.
Given the relatively few studies performed, any discovery about the spider is very valuable, concludes the scientist.(Por: Fin/FGA/sup/fgd