Sea Spider with Young

Nymphon robustum. Jan Mayen Island in the Greenland Sea, Norway. 1885.

Sea spiders are some of the most enigmatic of animals; their classification is unclear to this day. In particular males with young can be seen in very few museums.

ALL LEGS AND NO BODY
Sea spiders are marine animals with a tiny, rod-like body and four extremely long pairs of legs of very differing shapes: scissor legs to grasp food, feeler legs thick with hair, walking legs that can be shed in case of danger and grown back again, and ovigerous or egg-bearing legs. In females, these are often underdeveloped or lacking completely; the males can carry batches of up to a thousand eggs on these legs and hold onto their hatched young, which they still carry with them for a while.
The name “sea spider” is misleading. Today, the group is classified neither as spiders nor crabs, but is its own class within the chelicerates (Cherlicerata). To date, approximately a thousand different species of sea spider have been described, but new species are constantly being found in the deep sea.
All sea spiders live at the bottom of the sea and are predatory. They especially like soft-skinned animals such as snails, moss animals, sponges and polyps, which they grasp with their pincers and suck out with their proboscis. They appear to be immune to sea nettle toxins.
Sea spiders prefer cold water and are, therefore, particularly prevalent in the Arctic Ocean. The sample on display was collected in 1882 on an Austro-Hungarian deep sea expedition by the ship’s doctor Ferdinand Fischer in the Greenland Sea, between Iceland and Spitzbergen. “There were ten full-grown samples of this species at a depth of 200-270 meters, on a sandy seafloor, including a male covered with numerous young” Fischer reported in his “observations” on the expedition.