Giant sea spiders call Antarctica home

In order to test their theory, the team had to catch some of the spindly-legged creatures (PycnoWatchThis/YoutTube)
In order to test their theory, the team had to catch some of the spindly-legged creatures (PycnoWatchThis/YoutTube)

As tempting as it may be to escape the New Zealand heat and pop down to Antarctica for a holiday, new research reveals arachnophobes should probably stay away.

It turns out its frigid polar waters might be the ideal home to help sea spiders grow abnormally large – some of the ones found in Antarctica have a leg-span of around 25cm.

Antarctic waters have helped more than just the usually small sea spiders live large, with copepods, echinoderms and certain mollusks also growing larger than their cousins living in warmer waters, according to Hakai Magazine.

The team of researchers from the United States Antarctic Program, National Science Foundation, University of Montana and University of Hawaii at Manoa hypothesised so-called "polar gigantism" was caused by the higher concentration of oxygen in cold water compared with warm water. Antarctica's water, they say, has an especially high concentration of oxygen.

Increased oxygen concentration in chilly water is believed to combine with cold slowing their metabolism to help the sea spiders and other creatures grow supersized – a slower metabolism means they require less oxygen to survive, so it's speculated they're putting all that extra oxygen to good use by growing freakishly large.

In order to test their theory, the team had to catch some of the spindly-legged creatures. A hole was drilled in the thick sea ice near McMurdo Station before two specially-suited scuba divers went for a dip in water hovering between -1.5degC and -1.8degC – the freezing temperature of seawater.

The research, published in Hakai, tested the sea spiders in a variety of temperatures and water with varying levels of oxygen dissolved in it.

So far they've found larger sea spiders don't fare well in low oxygen water, seeming to support their hypothesis.

It's believed the system in Antarctica works especially well because instead of having gills or lungs, sea spiders absorb oxygen through diffusion. One researcher told Hakai the system wouldn't work well in large-bodied organisms unless there's a lot of oxygen available.

The team's research suggests climate change could put pressure on many marine invertebrates, as temperatures rise and oxygen levels fall.

With studies showing Antarctica may be irreversibly damaged by climate change, it's good to know at least it means there won't be more giant sea spiders roaming the world.

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