The sea spider is a unique creature that, despite being classified as a chelicerata, is actually more closely related to spiders than many other well-known groups of arthropods, such as insects and crustaceans. Its spider-like appearance gives it its obvious name. However, Pantopoda – as it is commonly known in scientific circles – is much larger and more unusual in appearance than most spiders. Some species even have 10 or 12 legs, and their thin legs and small bodies place them among the most curious creatures that marine biologists have studied.
The Size of the Sea Spider – In Search of the Largest Spiders
Although most species of sea spiders don’t grow to unusually impressive sizes – with some species being as tiny as 1 mm in diameter – a few unique specimens were discovered close to the Arctic and Antarctic Oceans that can grow to immense sizes of up to 90 cm in length. This is comparable to the size of the largest spider in the world, and researchers still don’t know what is causing the phenomenon. Some hypothesis point to the rich oxygen content of the waters close to the polar regions, while others consider that the diminished temperatures also play a key role. This phenomenon is known as polar gigantism, and it affects many other types of marine creatures, including copepods, mollusks and echinoderms.
Physical Characteristics of the Sea Spider
Sea spiders’ small bodies make a respiratory system obsolete, which means the organism manipulates gases through the process of diffusion. This is considered an important detail in solving the mystery of polar gigantism and its impact on giant sea spiders. Some of the spiders are so tiny that their small muscles each consists of a single cell. Many species in this group have either four or six pairs of legs, with some also featuring appendages that resemble legs.
Where Can You Find Sea Spiders?
These animals dwell in many different areas of the world, including the United States, Australia, New Zealand, the Mediterranean and the Caribbean Sea. Most commonly you can spot them in shallow waters, although some species can be found as deep as 7,000 meters below the surface. Most sea spider species will be spotted on the seabed using their large legs to move around and feed on small organisms such as cnidarians, bryozoans or sea sponges.