- Kingdom: Animalia
- Phylum: Arthropoda
- Norwegian: leddyr
Characteristics:Arthropods are a very successful group of species, due their ability to adapt to a wide range of environments. They are found both on land, in the air as well as in water. They are invertebrates with an external skeleton (exoskeleton) and segmented body, each with a pair of legs. When they grow they need to get rid of the old shell and form a new one. In this period they are especially vulnerable. They come with a wide range of respiratory systems, like lungs or gills. Many of the smallest species depend on osmotic transfer of oxygen directly through the body surface.
Arthropoda includes more than a million described species, organized in four subphyla:
- Chelicerata, currently including the sea spiders, a marine class of arthropods called Pycnogonida.
- Crustacea, the by far the largest group of marine arthropods
- Hexapoda, a mainly terrestrial group including all the six-legged insects we are so familiar with.
- Myriapoda, a terrestrial group of species with hundreds or even thousands of legs.