Largest sea spider

The world's largest species of sea spider or pycnogonid is the giant sea spider Colossendeis colossea, which has only a tiny body but a leg-span of up to 70 cm, and was formally described by science in 1881. Like all sea spiders, this strange-looking arthropod seems on first sight to be little more than a collection of very long legs, and indeed, the legs account for so much of its entire form that they even contain certain of its vital organs, such as the gonads and outgrowths of the gut. It feeds upon jellyfishes and other cnidarians, and exists in tropical to polar waters within the Antarctic, Northeast Atlantic, Indo-Pacific and Arctic Oceans.

Sea spiders are not true spiders, but constitute an entirely separate taxonomic class of arthropods, quite distinct from all others. Indeed, some zoologists consider it likely that they constitute a sister group to all other living arthropods and that they are therefore the last of a very ancient lineage of arthropods that otherwise died out in prehistoric times.