What is Sea spider?
{{taxobox | name = Sea spiders | image = Sea_spider.jpg | image_width = 250px | fossil_range = late [[Cambrian]] {{ndash}} Present | regnum = [[Animal]]ia | phylum = [[Arthropod]]a | subphylum = [[Chelicerata]] | classis = '''Pycnogonida'''}} '''Sea spiders''' are [[ocean|marine]] [[arthropods]] of the [[class (biology)|class]] '''Pycnogonida'''. There are about 1,300 [[species]] of sea spiders, which are found around the world. Sea spiders are found in all [[ocean]]s, including the [[Mediterranean Sea]], [[Caribbean Sea]], and the [[Arctic Ocean]]. Species found in coastal waters are usually small and have a leg span of about 1&nbsp;inch (2.5&nbsp;cm), those living at great depths, up to 24&nbsp;inches (60&nbsp;cm). Sea spiders are not true [[spider]]s, or even [[arachnid]]s. Their traditional classification as [[Chelicerata|chelicerates]] would put them closer to true spiders than to other well-known [[arthropod]] groups, such as [[insect]]s or [[crustacean]]s. However, recent genetic evidence suggests they may be an ancient sister group to all other living arthropods.<ref>{{cite journal |doi=10.1038/nature08742 |pmid=20147900 |title=Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences |journal=Nature |volume=463 |issue=7284 |pages=1079–83 |last=Regier, Jerome C. ''et al '' 2010 |year=2010 |bibcode=2010Natur.463.1079R |s2cid=4427443 }}</ref><ref>{{cite journal |doi=10.1093/molbev/msu235 |pmid=25107551 |title=Phylogenomic interrogation of Arachnida reveals systemic conflicts in phylogenetic signal |journal=Molecular Biology and Evolution |volume=31 |issue=11 |pages=2963–84 |last=Sharma P.P. ''et al'' 2014|year=2014 }}</ref><ref>Dunlop J.A. & Arango C.P. 2005. Pycnogonid affinities: a review. ''Journal of Zoological Systematics and Evolutionary Research''. '''43''': 8–21. [http://onlinelibrary.wiley.com/doi/10.1111/j.1439-0469.2004.00284.x/abstract;jsessionid=AFBDE12009D0E2E44CB9C001AEA3F597.f02t01]</ref> == Description == The sea spider has a small, narrow body. I