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The Seashore

Sea Spiders (Pycnogonids)

Sea Spiders (Pycnogonids)

The sea spider, Nymphon, carrying eggs on the ovigerous legs held under the body.

The Sea Spiders are not true spiders at all but belong to their own group, unique to the marine environment. They are superficially like spiders but have just a cephalothorax (a head and thorax together) with the abdomen reduced to a single segment. Coming off the thorax are four pairs of very long legs with claws at the end. The head has a long proboscis. Eyes are located on the segment holding the first pair of legs. Also attached at this point are a pair of ovigerous legs. These hold the eggs, although it is the male that does this after the eggs have been laid by the female. The genus Pycnogonum is similar but more robust and with shorter legs. All sea spiders are around 1 cm in length although easily overlooked.

The Sea Spiders crawl around the rocks, crevices and seaweed looking for the prey, which are mainly hydroid colonies and Bryozoans. These are consumed using the proboscis after they get wrenched off by the tiny chelicerae (pincers). Small anemones, corals and sponges are also consumed.

Found on rocky seashores they are found in the middle but mainly the lower shores. Found on all seashoresaround Europe.


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