A new paper has found bat-eating spiders exist on every continent except Antarctica, with bats falling prey more often than expected.
Though bats are typically preyed on by vertebrates (with hawks, snakes and owls their most common predators), there are some invertebrate species quite partial to the taste of bat. We've previously written about the giant Venezuelan centipede Scolopendra gigantea, which hangs from cave ceilings and snatches bats as they pass (
http://on.fb.me/ZYIdcT). However, spiders eating bats was thought to be quite rare.
When two recent studies both reported spiders having bat for dinner, researchers wondered if this behaviour was more common than suspected. After analysis of over 100 years worth of reports, together with interviews from bat and spider researchers, they found over 50 cases worldwide of spider attacks on bats.
90% of these attacks happened in habitats around the equator and 40% occurred in the neotropics (South America and tropical regions of North America). Interestingly it wasn't just web-spinning spiders - 12% of attacks were by spiders such as huntsmen and tarantulas, which forage rather than make webs. In one case, a fishing spider was seen attempting to kill an immature bat (though it was scared off by photographers).
The authors point out that bat captures are likely still rare. It's probable bats can detect webs using their echolocation abilities and even if a bat does fly into a web, only the strongest webs can take the impact without breaking. Unsurprisingly smaller bats are more vulnerable to spider web entanglement (and in some cases, it was exhaustion and dehydration resulting from this entanglement that killed bats rather than direct spider attacks).
To read the paper:
http://bit.ly/13Z3QwT
Photo: A small bat entangled in the web of a Nephila pilipes spider in Australia. The spider appeared to be feeding on the dead bat. Credit to Carmen Fabro.
__________________