If you have an aversion to spiders, you may want to cancel that diving trip to the Antarctic. Fortunately though you will probably never run into the mammoth sized arachnids, they only reside in the waters of antarctica. Scientists are still uncertain why they grow to such gigantic proportions.
These spiders are just one of the species that has been observed in the polar regions with this type of gigantism. It seems something in these cold waters is allowing the species to support these humungous body sizes. However, scientists are yet to determine exactly what elements are allowing for this mammoth growth.
Several hypotheses do exist. Some scientist speculate that the gigantism is simply an evolutionary trait that allows the species to sustain long periods of starvation during the winter months when resources get thin in the polar regions. Other purpose that these species have descended from creatures from the deep sea where gigantism has also been observed.
A recent study seems to support a different theory revolving around oxygen availability in the polar regions. The water in these regions can hit 29 degrees Fahrenheit (-1.8 Celsius) which lends it to carrying more oxygen because oxygen is more soluble in cold water than warm water. The theory states high levels of oxygen coupled with the fact that low temperatures slow animals’ metabolism and reduce their need for oxygen can lead to this gigantism.
To test this hypothesis, a team of marine biologist drilled beneath the Antarctic sea ice where they had previously encountered these giant sea spiders. Okay, so these are not technically spiders but a arthropod call pycnogonids. Normally pycnogonids are pretty small but they have been observed al big as 20 inches (50 centimeters).
Once the team collected samples, they performed a series of experiments to determine the effect of changing oxygen levels on their subjects. Hakai Magazine reported that the placing spiders in lower oxygen water had a negative impact on their well-being. Suggesting that the oxygen rich waters of the Antarctic may well be vital to thrive as giants.
The science is far from conclusive and much more work is needed to definitively state what causes polar gigantism. The mystery of the gigantic sea spider still exists.