Seven species of spiders previously unknown to science have been discovered in caves in Israel. Two of these subterranean species are not only blind, they have completely lost their sight. The other five still have eyes but are corrupt. "You can see that these five have eyes - but they're very small. There's something there but their eyes are working? We don't know," said Dr. Efrat Gavish-Regev, team director at the Hebrew University of Jerusalem. All seven branched out from the great funnel-web spider tree found everywhere except the North Pole and the two poles. Normally, funnel-web spiders have a full complement of eight arthropod eyes, attractively arranged in two horizontal rows. Miraculously, genetic analysis shows that their closest relatives aren't the spiders that live just outside their homes, or even in the caves next door. Instead, they are in Cyprus, Turkey and Libya, Shlomi Aharon, Gavish-Regev and colleagues report in the journal Molecular Phylogenetics and Evolution. Open gallery view Tegenaria ornith Aharon & Gavish-Regev, 2023 - New blind species from a cave on the Carmel mountain ridge Shlomi Aharon Long legs and hairy The new spiders are just a handful of creatures previously unknown to science that have been underground in Israel since their research began in 2012; some have been discovered in caves that have been isolated from the outside world for millions of years. That's not the case for our spider ate. They evolved in caves that were physically open but apparently ecologically isolated, Gavish-Regev says. Most funnel-web spiders live in the open, but these seven Israelites are necessarily cave dwellers. Some have only been spotted in one cave. This is the extent of their known range, making them extremely vulnerable to extinction, especially since all seven have adapted to the primitive lifestyle - the "twilight zone" and the pitch-black deep cave - and are unable to survive outside their caves. As for the blind, it may be a cliché, but losing sight can lead to the development of special abilities. Here, blind spiders developed longer legs with longer hairs. The same goes for pedipalps. Their hairy pedipalps are believed to be developed sense organs primarily concerned with smell and taste. Open gallery view Striped lynx spider . The enlarged pedipalps serve as the male's external reproductive organs. Ryan Kaldari Gavish-Regev takes this opportunity to point out that, with the exception of a few families, such as jumping spiders and wolf spiders, other spiders may have eight eyes, but cannot actually see well. Does blindness break the web weaving? Not at all. "Funnel spiders create very specific webs," explains Gavish-Regev. Arachnids create a sheet with that namesake funnel in the middle. When an insect touches the sheet, the spider jumps out of its nest in the funnel, grabs the food and carries it back to the nest to eat. Cave spiders make the same kind of funnel-shaped nests, albeit smaller than their outside cousins—probably because there is less prey in the cave, so investing in a huge web is a waste of silk and energy, Gavish-Regev estimates. Open gallery view A spider with a funnel web and its funnel web. 1 credit So what do we have? Leaving the worldwide great funnel-web spider tree, spiders, as found in numerous animals from fish to lizards, became functionally – if not physically – isolated in their caves and developed adaptations to cave life: eyes shrunk or shrunk. As skin pigments disappear, other senses may become stronger. It is an excellent example of convergent evolution and shows that loss of eyes and skin pigment is evolutionarily insignificant. Open gallery view of Madagascar's blind cave fish. Frank Vassen climatic remains Now the story gets weird. There are two hypotheses underlying speciation in caves: the Adaptive Shifts hypothesis and the Climatic Relict hypothesis. The Adaptive Shifts hypothesis postulates that when lifeforms realized that a new niche had opened up, they colonized caves, found good food inside, and eventually stayed there, adapting over time. Adaptive Transitions can explain speciation when a closely related spider is found inside a cave to one outside the cave. He can't explain why the blind seven's closest cousins ​​are in the Mediterranean and the Red Sea, and not the spiders just outside the cave. The Climatic Relic hypothesis suggests that ancestral species were very common millions of years ago. Descendants of ancestors live to this day in Cyprus, Libya and Turkey. But in Israel, due to historic climate change, this ancestor perished outside – leaving only isolated pockets of spiders in these caves that were protected from disaster. Gavish-Regev says the team believes this is the case. Open gallery view Tegenaria pagana's eyes are normal, found at the entrance of many caves in Israel, Credits: Shlomi Aharon Further analysis may shed light on when the common ancestor went extinct locally. But as a ballpark figure, Gavish-Regev suggests he lived perhaps 7 to 15 million years ago. Israel was never covered by ice sheets during the ice ages, but has been subject to various climate change scenarios over the ages. Caves may not have been physically insulated with collapsed ceilings, but when climate change came along—making the outside hostile to poor spiders—they became effectively isolated, he summarizes. A famous example of effective species isolation is Ma'arat Hanetifim , a gorgeous spot that has different species from the surrounding Judean Hills. It's worth noting that the climate change looming over us today is expected to include not only higher temperatures but also drought, so it's unlikely that these spiders will be coming out of their caves anytime soon.