Sea spiders of the Pacific Northwest may resemble land spiders, but are very bizarre and unique marine creatures.  These animals do not have a respiratory system, and since their bodies are so thin they rely on gas exchange by diffusion.  Also because the main body is too small to accommodate all of the organs, some extend deep inside the length of their legs.  These strange marine arthropods are not always easy to spot and it is exciting to find one on a rare occasion while diving.