We finally had a long dive day yesterday! As part of our science outreach/ as a thank you to all the folks working where we are staying, we put up an aquarium of Boulder Patch critters. One of the animals we picked up for the aquarium was this guy:
This is a pycnogonid, or sea spider. While they are related to land spiders, they are actually more closely related to horseshoe crabs. These guys are pretty weird. Their skinny body means that they don’t need a respiratory system – gases can just move in and out of their body via diffusion. Because their body is mostly legs, their guts go through their legs as well. The males have long arm-like appendages that hang from their middle that they use to carry eggs. The one we got is a male, can you tell?
In most places, pycnogonids are small (<1 cm), but can get rally big in the Arctic and Antarctic. In the deep sea, they can get over two feet long! They are predators, feeding upon other invertebrates by sucking up their soft bodies with a proboscis. Hopefully this one will be happy in our tank and not eat too many of his tankmates!