Description Sea spiders: are marine arthropods of order Pantopoda, belonging to class Pycnogonida, hence they are also called pycnogonids. They are cosmopolitan, found in oceans around the world. There are over 1300 known species, with legs ranging from 1 mm to over 70 cm.
Description Spiders: are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms.