sea spider


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sea spider,

common name for members of the class Pycnogonida, long-legged, rather spiderlike organisms of the subphylum Chelicerata, widely distributed in marine waters. Most are tiny, from 1 to 9 mm (0.04–0.36 in.), and live in littoral regions, crawling about over the surface of sessile animal colonies or seaweeds. Some live on or in clams. There are deep-sea forms, some becoming quite large; Colossendeis colossea has a leg span of nearly 2 ft (91 cm). Their unusual body form makes their relationships to other arthropods obscure. Nearly all of the body is composed of the anterior region (prosoma); a tiny tubular posterior region (opisthosoma) projects behind. A large proboscis is used to suck in food. At the base of the proboscis is a pair of modified appendages (chelicera) used to pick off bits of food and hold them in front of the mouth. The next appendages are a pair of leglike pedipalps, followed by a pair of specialized legs used by the male to carry eggs until they hatch. Four pairs of walking legs follow, but sometimes additional pairs are found. Members of this class are relatively common and widely distributed; well over 400 species are known. Sea spiders are classified in the phylum ArthropodaArthropoda
[Gr.,=jointed feet], largest and most diverse animal phylum. The arthropods include crustaceans, insects, centipedes, millipedes, spiders, scorpions, and the extinct trilobites.
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, subphylum ChelicerataChelicerata
, subphylum of Arthropoda, including the horseshoe crabs (order Xiphosura), the arachnids (class Arachnida), and the sea spiders (class Pycnogonida). The extinct giant water scorpions (order Eurypterida, not true scorpions) also are chelicerates.
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, class Pycnogonida.

sea spider

[′sē ‚spī·dər]
(invertebrate zoology)
The common name for arthropods in the subphylum Pycnogonida.
References in periodicals archive ?
New sea spiders from the Jurassic La Voulte-sur-Rhone Lagerstatte.
A"Gigantism is very common in Antarctic waters - we have collected huge worms, giant crustaceans and sea spiders the size of dinner plates,A" Australian scientist Martin Riddle, voyage leader on the research ship Aurora Australis, said yesterday.
Most species of fish, worms, sea spiders, and other animals, plants, and other organisms that live in the waters of Antarctica don't live anywhere else, Stoddard says.
The tropics have long been hailed as rich in species, yet sea spiders may be most diverse in, of all places, Antarctica.
Chiefs at Seahawks (-3): If Gunther Cunningham were not a football coach, I believe he would be a marine biologist specializing in the sleeping patterns of pycnogonid sea spiders and stalked crinoids.
He told The Scotsman that among the most fascinating species were the huge sea spiders.
The sea spiders are perhaps the most characteristic of the cold areas, and these had been previously known to inhabit the Arctic Ocean living even below its present day ice cap.