Seven new spider species were uncovered in Israel recently, all of them found deep inside caves, some with very poor eyesight and some completely blind.

Researchers from the Hebrew University of Jerusalem and the Israeli Natural History Collections examined spiders in caves around Israel to examine the evolutionary ties between spiders from the Agelenidae family living at the front and back ends of caves.

The spiders at the front of the caves can see, whereas those living deep inside the cave cannot, and the researchers wanted to determine which species are the most similar to one another.

“Caves have long been recognized as a window into the mechanisms of diversification and convergent evolution, due to the unique conditions of isolation and life in the dark,” the researchers note in their study, which was recently published in the journal Molecular Phylogenetics and Evolution. “These lead to adaptations and reduce dispersal and gene flow.”

They discovered seven new cave-dwelling spider species, five of them with eye reduction and two completely blind. Two of the species were found in multiple caves, and five were endemic to each of their caves.

Genetic testing showed that the newly discovered species were evolutionarily more similar to spider species living in southern Europe’s Mediterranean regions than to the spiders dwelling at the entrance to their own caves. It’s possible that the newly discovered spiders are a relic of a more ancient species that became extinct.

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