Home > Sea spider

Sea spiders, also called Pantopoda or pycnogonids, are marine arthropods of class Pycnogonida. They are cosmopolitan, found especially in the Mediterranean and Caribbean Seas and the Arctic and Antarctic Oceans. There are approximately 1,000 known species, ranging in size from 1-10 mm to over 90 cm in deepwater species: most are toward the smaller end of this range.

The correct taxonomy within the group is uncertain, and it appears that no agreed list of orders exists. Accordingly, families are listed in the table at the right. Furthermore, the evolutionary lineage of the sea spider group as a whole is disputed: their fossil record is sketchy at best, with the three earliest known genera originating in the Devonian. Some believe (or once believed) sea spiders to be among the chelicerates, together with horseshoe crabs, true spiders, miteTetranychidae Spider mites Eriophyidae Gall mites Sarcoptidae Sarcoptic Mange mites The mites and ticks, order Acarina or Acari belong to the Arachnida and are among the most diverse and successful of all the invertebrate groups, although some way behinds, tickThis article is about the parasitic arachnid. For the fictional superhero, see The Tick. For the v-shaped mark denoting that something has been noted, completed, is correct, etc. see check''. A clock tick is, especially in computing, the smallest unit ofs and scorpionA scorpion is an invertebrate animal with eight legs belonging to the order Scorpiones in the class Arachnida. Physical characteristics The scorpion body is divided into 2 main segments the cephalothroax and the abdomen, the cephalothroax consists of thes. While sharing many morphological features with the other chelicerates, major differences (such as their unique proboscis) have caused some taxonomists to remove sea spiders from this grouping.

Their reduced body size is in contrast to large, long legs, which may be present in four or more pairs. Because of their small size and slender body and legs, no respiratory systemThe respiratory system is the biological system of any organism that engages in gas exchange. Even trees have respiratory systems, taking in carbon dioxide and emitting oxygen. Respiratory system in humans and animals In humans and other mammals, the resp is needed for gas diffusion . A proboscisIn general, a proboscis is an elongated appendage of a living organism. The most common usage is to refer to the tubular feeding and sucking organ of certain invertebrates like insects, worms and mollusks. The elephant's trunk is also called a proboscis. allows them to suck nutrients from soft bodied invertebrates, and their digestive tract has branches extending into their legs, known as diverticulae.

Their habitats range from the shallow intertidal zones to deepwater benthic environments, some 7,000 metres down. Sea spiders do not swim but rather walk along the bottom with their stilt-like legs. Most are carnivorous and feed on cnidarians, hydroid s, sponges, soft corals, polychaetes and bryozoans.