Sea spiders are marine arthropods of the order Pantopoda, belonging to the class Pycnogonida, hence they are also called pycnogonids. They are cosmopolitan, found in oceans around the world. The over 1,300 known species have leg spans ranging from 1 mm (0.04 in) to over 70 cm (2.3 ft). Most are toward the smaller end of this range in relatively shallow depths; however, they can grow to be quite large in Antarctic and deep waters.
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Hedgpethia is a genus of sea spider, in the family Colossendeidae. The genus was named after the marine biologist and sea spider specialist Joel Hedgpeth.
William Thomas Calman was a Scottish zoologist, specialising in the Crustacea. From 1927 to 1936 he was Keeper of Zoology at the British Museum.
Nymphonidae is a family of sea spiders which has representatives in all the oceans. This family contains some 250 species, most of which are found in the genus Nymphon. Nymphonid bodies are between 1 and 15 mm long, the extent between the points of the legs reaching 150 mm. Most species are predators of hydroids. Like most sea spiders, species in this family have four pairs of legs, except for Pentanymphon antarcticum, which has five pairs, and Sexanymphon mirabilis, which has six pairs.
Cyclaspis is a genus of cumacean crustaceans in the subfamily Bodotriinae, containing the following species:
Nymphon is a genus of sea spiders in the family Nymphonidae. The species of sea spiders within the genus Nymphon are all benthic organisms and are found in abyssal and bathyal areas of the ocean. This is a fully marine group and can be found at various depths ranging from the littoral zones to the deep sea. They are found in most major oceans across the globe with a strong distribution around polar regions: Arctic and Antarctic waters. Out of the sea spider genus, Nymphon is the most rich, with a majority of the species within the genis being found in the Southern Ocean region. This genus may also contain bioluminescent species.
Pycnogonum is a genus of sea spiders in the family Pycnogonidae. It is the type genus of the family.
Ammotheidae is the most diversified group of the class Pycnogonida, with 297 species described in more than 20 genera, of which only Nymphopsis and Sericosura were found to be monophyletic. Despite its internal taxonomic uncertainty, studies on 18S rRNA supports its monophyly, and the subdivision on Achelinae and Ammotheinae subfamilies.
Achelia is a genus of pycnogonids in the family Ammotheidae.
Tanystylum is a genus of pycnogonids in the family Ammotheidae.
Colossendeis is a genus of sea spider belonging to the family Colossendeidae. Phylogenetic analysis indicates that this genus is paraphyletic with respect to the genera Decolopoda and Dodecolopoda, which are found to be nested within the genus Colossendeis in a phylogenetic tree.
Callipallene is a genus of sea spiders in the family Callipallenidae. There are more than 30 described species in Callipallene.
Rhopalorhynchus is a genus of sea spiders in the family Colossendeidae.
Phoxichilidium is a genus of sea spiders within the family Phoxichilidiidae. Members of this genus can be found in all oceans at depths up to 1074 meters.
Dodecolopoda is a monotypic genus of sea spider in the family Colossendeidae. The only species in this genus is Dodecolopoda mawsoni, first described by William Thomas Calman and Isabella Gordon in 1933 based on a male holotype found off the coast of MacRobertson Land. Calman and Gordon named this species for Sir Douglas Mawson, who obtained this specimen on his voyage to the Antarctic region in 1931.
Decolopoda is a genus of sea spider belonging to the family Colossendeidae. This genus includes two valid species, D. australis and D. qasimi. As the name of this genus implies, these two species are among the seven species of sea spider with five pairs of legs instead of the usual four leg pairs.
