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Eek! Eyeless Spiders Come to Light in Dominican Cave

Image: Ciba seibo
The blind cave spider known as Ciba seibo is about three-tenths of an inch (8 millimeters) long. Specimens were found on the cave floor, under stones in a dark area. Bloom et al. / Journal of Arachnology

Eyeless spiders don't sound like the sorts of things you'd want to seek out, but when you find them in the Dominican Republic — well, that's something to celebrate.

Two previously unknown species of blind cave spiders were discovered two years ago in Cueva Seibo, a cave in the Dominican Republic's Parque Nacional Del Este, or East National Park. They're described in a paper published online July 30 by the Journal of Arachnology, with Lewis and Clark College research assistant Trevor Bloom as the lead author.

The researchers say the two species, known as Ciba seibo (shown at top) and Trichopelma maddeni, are the first eyeless cave spiders to be discovered on the island of Hispaniola. This is also the first documented instance of two different species of blind spiders being discovered in a single cave, according to the American Arachnological Society.

Trichopelma maddeni is a barychelid spider, a relative of tarantulas, that measures more than 6 inches (15 centimeters) in length. This specimen was collected from a dark zone of the cave, under stones of the cave floor. The blind spider has vestigial eyes. Bloom et al. / Journal of Arachnology
Cueva Seibo, shown here, is located in the Dominican Republic's East National Park, as indicated on the inset map. The cave has a relatively small bat population, which researchers say may help explain why eyeless spiders are able to survive there. Bloom et al. / Journal of Arachnology

There are about 1,000 described species of eyeless spiders around the world, but fewer than 30 of them have been discovered in caves in the tropics. Eyeless spiders rely on vibrations and chemical cues to find their prey. So if you ever find yourself in Cueva Seibo ... tread lightly.

IN-DEPTH

In addition to Bloom, the authors of "Discovery of Two New Species of Eyeless Spiders Within a Single Hispaniola Cave" include Greta Binford, Lauren Esposito, Giraldo Alayon Garcia, Ian Peterson, Alex Nishida, Katy Loubet-Senear and Ingi Agnarsson.