It appears that the tarantula’s ubiquity traced back to the Cretaceous period, according to Carnegie Mellon University researchers. The scientists have undertaken a global review of into the ecological history of the spider.
Tarantulas are among the more scary-looking type of spider: Large, hairy, coated with vibrant colors and they are found in many parts of the world. The spiders belong to the family Theraphosidae and there are around 1,000 different species. There are similarities and differences; some of the spiders hunt prey primarily in trees; whereas others hunt on or near the ground. A commonality is that all tarantulas can produce silk. Another shared feature is with tarantulas being very sensitive to vibrations in the ground that may indicate the presence of prey or danger.
To gather the necessary data to answer questions about the spread of tarantulas, the researcher examined transcriptomes (the sum of all the transcripts from the mRNA – messenger ribonucleic acid, which is read by a ribosome in the process of synthesizing a protein). This was undertaken for hundreds of tarantulas across multiple time periods.
This enabled the researchers to construct a genetic tree of spiders. These data were then time-calibrated their tree with fossil data. This revealed that all tarantulas are ancient, dating back some 120 million to the Cretaceous period.
The geographical spread of the spiders will have related to a time when the major continents were joined. Within the geographical spread, there are two distinct lineages of tarantulas: Those that are ground dwelling and those that are predominantly arboreal.
The research features in the journal PeerJ, in a paper titled “Phylogenomic analyses reveal a Gondwanan origin and repeated out of India colonizations into Asia by tarantulas (Araneae: Theraphosidae).”
