Gazing into the depths of a pond, it's hard to miss the insects that whirl and zip beneath the surface. However, only one species of spider has joined them: the diving bell spider, Argyroneta aquatica. 'It is an iconic animal; I had read about the spider as a small boy in popular literature about ponds,' says Roger Seymour from the University of Adelaide. According to Seymour, each spider constructs a net of silk in vegetation beneath the surface and fills it with air carried down on its abdomen.
Foto: Stefan K. Hetz
Foto: Stefan K. Hetz
The spiders spend their entire lives submerged and even lay their eggs in their diving bells. Having already used an oxygen-measuring device called an optode to discover how aquatic insects extract oxygen from water through thin bubbles of air stretched across their abdomens, Seymour was looking for other small bubbles to test his optode.
'The famous water spider came to mind,' remembers Seymour, and when he mentioned the possibility to Stefan Hetz from Humboldt University, Germany, Hetz jumped at the idea. Inviting Seymour to his lab, the duo decided to collect some of the arachnids to find out how they use their diving bells. The duo report their discovery that the spiders can use the diving bell like a gill to extract oxygen from water to remain hidden beneath the surface in The Journal of Experimental Biology at http://jeb.biologists.org/content/214/13/2175.abstract
Sadly, diving bell spiders are becoming increasingly rare in Europe; however, after obtaining a permit to collect the elusive animals, the duo eventually struck lucky in the Eider River. 'My philosophy is to make some measurements and be amazed because if you observe nature it tells you much more than you could have imagined,' says Seymour. So, returning to the lab, the team reproduced the conditions in a warm stagnant weedy pond on a hot summer's day to find out how the spiders fare in the most challenging of conditions.
After watching the spiders build their shimmering diving bells, the duo gingerly poked an oxygen sensing optode into the bubble to see how the animal reacted. Miraculously, the spider was unperturbed, so they continued recording the oxygen level. 'Then it occurred to me that we could use the bubble as a respirometer,' says Seymour, to find out how much oxygen the spiders consume.
Taking a series of oxygen measurements in the bubble and surrounding water, the team calculated the amount of oxygen flowing into the bubble before calculating the spider's oxygen consumption rate and found that the diving bell could extract oxygen from the most stagnant water even on a hot day. Also, the metabolic rate of the aquatic spider was low and similar to the low metabolic rates of other spiders that sit waiting for prey to pass.
However, despite satisfying the spider's oxygen demands, the bubble continually shrinks because nitrogen diffuses back into the water, eventually forcing the occupant to venture to the surface to resupply the diving bell. So how long could the bubble survive before the spider had to dash up for air? Calculating the diffusion rate of nitrogen out of the bubble, Seymour and Hetz were surprised to find that the spiders could sit tight for more than a day. 'The previous literature suggested they had to come to the surface as often as every 20min throughout the day,' comments Seymour, who adds, 'It is advantageous for the spiders to stay still for so long without having to go to the surface to renew the bubble, not only to protect themselves from predation but also so they don't alert potential prey that come near.'
REFERENCE: Seymour, R. S. and Hetz, S. K. (2011). The diving bell and the spider: the physical gill of Argyroneta aquatica. J. Exp. Biol. 214, 2175-2181.
Kathryn Knight | EurekAlert!
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences