Collected from the Ross Sea shelf in southern Antarctica, this 9.8-inch-long (25-centimeter-long) giant sea spider was one of 30,000 animals found during a 35-day census in early 2008. The marine arachnids, which prey on hydroids and bryzoans - branching, coral-like animals - are larger and more common in Antarctic waters than anywhere else on Earth. Cold temperatures, few predators, and high levels of oxygen in seawater could explain their gargantuan size.