SEA SPIDER

Sea spiders" or pycnogonids, are members of Phylum Arthropoda, along with land spiders. Besides living underwater, sea spiders differ from their land cousins in other ways they don't spin webs, and may have from four to six pairs of long segmented legs, versus four pair for land spiders.
more species of sea spider most are very small, ranging from 1/100 inch to about 20 inches across. This one is small, only about 3/8 inch across. The largest sea spiders reside in the deep ocean. Deep-sea researcher Dr. Paul H.
Yancey notes large sea spiders are known to "stride over the abyssal mud with their long legs, using a proboscis to suck tissues from sessile prey..." and has photos of two such specimens on his deep sea pages web site.
At least one species of sea spider is known to feed on nudibranchs and other small gastropods, as noted in this archive page from one of my favorite online resources, the Australian Museum's Sea Slug Forum. Like their land-lubber cousins, sea spiders are carnivorous, some feeding on other invertebrates by sucking out the juices, while others tear their prey apart and pass it into a proboscis for feeding.