Nombres alternativos: Pantopoda, pycnogonids
Sea spiders live in oceans throughout the world, with species of smaller sizes living in relatively shallow depths and larger species living in the Antarctic and deep waters.
Sea spiders have a leg span ranging from 1 mm to over 70 cm and their long legs contrast with their small body size. They usually have eight legs, but among the 1,300 known species of sea spiders
there are some which have five and six legs.
Due to their general small size and their thin body and legs, they evolved to not need a respiratory system anymore and gases move by diffusion in and out of their bodies.