Sea spiders, also known as pycnogonids, are a group of marine arthropods that can be found in oceans around the world. Although they are called "spiders," they are not true spiders and have unique characteristics that make them special. Some synonyms that can be used for sea spiders include marine spiders, ocean spiders, sea creepers, and merospiders. These creatures have long, slender legs that exceed their bodies' size and are found in a variety of colors and sizes. Despite their unusual appearance, sea spiders play an essential role in the ocean's ecosystem and are an intriguing subject for marine biologists to study.