Arachnida
Arachnida is a class of joint-legged invertebrate animals that includes spiders, scorpions, ticks, mites, harvestmen, and other related creatures. While most arachnids are terrestrial, a small number of species have adapted to marine environments. These marine arachnids are primarily found in coastal waters and are generally small and inconspicuous.
Characteristics
Marine arachnids share many of the same characteristics as their terrestrial counterparts. They have eight legs, a body divided into two main parts (cephalothorax and abdomen), and simple eyes. Unlike most terrestrial arachnids, marine species lack book lungs and instead rely on gills for respiration. They also have special adaptations for life in the ocean, such as flattened bodies and specialized appendages for clinging to rocks or seaweed.
Environments
Marine arachnids can be found in a variety of coastal habitats, including rocky shores, tide pools, and seagrass beds. Some species are even adapted to living in the intertidal zone, where they must cope with fluctuating levels of salinity and oxygen.
Common Names
While most arachnids are known by common names like spiders, scorpions, and ticks, marine arachnids are not as widely recognized. They are often referred to by their scientific names or as "sea spiders" or "marine mites".
Examples of Marine Arachnids
- Pycnogonida (Sea Spiders): These are the most familiar group of marine arachnids. They have long, thin legs and a small, reduced body.
- Halacaridae (Marine Mites): These are small, microscopic mites that live in marine sediments and algae.
- Hydrachnidia (Water Mites): This group includes a variety of mites that are semi-aquatic or fully aquatic. They are often found in freshwater, but some species occur in marine environments.
References
Wikipedia: Arachnida
ScienceDirect: Marine Arachnida
ResearchGate: Marine Arachnida