Sea spiders are marine arthropods. They are cosmopolitan, found especially in the Mediterranean and Caribbean Seas and the Arctic and Antarctic Oceans. There are over 1300 known species, ranging in size from 1-10 mm, to over 90 cm in some deep water species. Most are toward the smaller end of this range in relatively shallow depths, however, they can grow to be quite large in Antarctic waters.
"Sea spiders" are not actual spiders. They are not even arachnids, but more distantly related arthropods.
