Water Spiders Spin Personal “Scuba Tanks”

While some spiders spend their days spinning webs and collecting food on land, the unique water spider found most commonly in eastern Australia and Tasmania thrives in freshwater ponds, creeks and marshes and spends its entire life underwater. This is possible thanks to the creation of a basic “scuba tank” spun form their very own silk. Scientists refer to these tanks as air bells, which act as reservoirs for holding and replenishing oxygen levels to sustain the life of these small brown arachnids. The water spiders are able to trap air bubbles from the water’s surface using the short hairs on their abdomens and legs. Then the spiders carry the bubbles back to their homemade underwater tank for storage. As the spider continues to do this, the tank becomes bell shaped and silvery. The specific silk that the spider uses is important in this process because it allows for oxygen to diffuse in from the water and carbon dioxide to diffuse out, so the spiders do not have to keep replenishing their supply so often.

Even though the creation of an “external lung” is quite impressive, the air bells serve other purposes than just holding oxygen. The water spider can use their air bell as a place where they can hide away from predators. They can also use this safe harbor when they themselves are the predators. In this case, the air bell acts a place where they can take a water mite, or mayfly nymph back and safely consume their prey. When the time comes for breeding and production the water spider also uses the air bell as a safe place to create a nest in which to keep her eggs. From this you could assume that females spend a considerable amount of more time in the air bells. With all of these conveniences of home right underwater, it’s no wonder why the water spiders would ever want to come up for air.

Source: http://news.nationalgeographic.com/news/pf/23715169.html

http://www.naturegrid.org.uk/biodiversity/invert/spiderw.html



posted by: Caitlin Sanders