Prehistoric Cave Discovered; 8 New Species Thrive Inside

Mati Milstein in Ramle, Israel
for National Geographic News

June 2, 2006

Quarry workers digging recently in central Israel broke through bedrock
and stumbled into an entirely new and unique ecosystem, scientists announced Wednesday. The cavern had been sealed
off from the outside world for millions of years.

When researchers entered the cave through a small passage, they found eight ancient animal species that had never been seen before.

At 1.6 miles (2.5 kilometers) long, the newly named Ayalon Cave is Israel's second largest known limestone cave. The underground chamber stretches some 330 feet (100 meters) deep, near the town of Ramle, not far from the city of Tel Aviv (Israel map).

"The eight species found thus far are only the beginning" of what promises to be "a fantastic biodiversity," researcher Hanan Dimentman, of the Hebrew University of Jerusalem's Alexander Silberman Institute of Life Sciences said in a statement.

Four of the new species are water-dwelling crustaceans. Four others are land-based invertebrates—creatures without spines.

Also found in the cave were bacteria that serve as the basic food source in the self-contained community.

As might be expected of species confined to a pitch-black cavern for millions of years, none of the newly discovered animals had eyes.

All were alive, except for a scorpion-like creature—the only known representative of its species.

Unusually, two of the crustaceans found in the cave are saltwater species. The two others are of a type found in fresh or brackish (slightly salty) water.

Today's Mediterranean Sea is a remnant of the Neotethys ocean basin, which was formed during the Late Triassic and Early Jurassic periods, about 200 million years ago.

The current mix of freshwater and saltwater species in Ayalon Cave may be the result of events that occurred when what is now Israel was covered by that ancient sea.

Specimens were sent to biologists in Israel and overseas for further analysis and precision dating.

Hebrew University geography professor Amos Frumkin, who was involved in the study, describes the cave as "unique in the world."

The chamber is situated under a layer of chalk impenetrable to water and includes an underground lake that is part of one of Israel's two aquifers, vast underground water deposits embedded in rock, gravel, and sand.

The newfound lake, however, is different in temperature and chemical composition from the main waters of the aquifer.

Experts in cave ecology and evolution agree the discovery of Ayalon Cave is extremely significant.

Francis Howarth is an entomologist and cave explorer with the Hawaii Biological Survey in Honolulu. (See a photo of rare baby spiders found in a Hawaii cave.)

Howarth says Ayalon Cave can supply researchers with a treasure chest of new data on evolutionary ecology and biodiversity.

"This discovery is exceptionally significant regionally," Howarth said. It indicates "that there must be similar systems in other deep aquifers in the Mideast. …"

New York University evolution expert David Fitch isn't sure how unique the Israeli discovery is. But he says the new findings may help fill in evolutionary blanks.

"There are many examples of cave ecosystems. Many of these caves, like other geographically isolated systems such as oceanic islands, have a high proportion of endemic species found nowhere else," Fitch said.

"So the finding that there are several new species of invertebrates [in Ayalon Cave] is not really very novel," he said. "However, there may be significance with regard to helping … fill in the branches of the 'tree of life'"—the history of evolutionary relationships among life-forms.

The researchers behind the new study say they hope to discover more species in the underground cave. Hebrew University's Dimentman believes they will find live scorpions and predator species higher up in the food chain.

Nesher Industries, the owners of the quarry under which the cave was discovered, says it will seek to preserve the ecosystem and the findings it contains. The cave is currently closed to the public as researchers continue their work.

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