The crustaceans are a subphylum of the phylum of Arthropoda to which over 52,000 species belong. Crustacea occur in salt and fresh water and some of them even outside the water. Through the multitude of species as well physique and reproduction as way of life and habitat are widely diversified. At least in the Canary Islands, I have so far noticed that all Crustacea fluoresce!
Due to the diversity of the Crustacea, it is difficult to find common features. But they exist. Basically, the body of crusting consists of a number of segments delimited by the head and end sections. Another one is the number of antennas. There are two pairs, which is why Crustacea are also called Diantennata. In addition, they have biramous legs like all Arthropoda. This means that one leg runs out into two endings. In addition, the split legs depending on specialization can be converted into mouth tools, suction cups, genital organs, etc..
Habitat and Distribution
Apart from a few exceptions, Crustacea live in the water. They settle all kinds of waters. Crustacea are found in tropical waters as well as under arctic ice.
Cretaceous colonize reefs, crevices, open water, surfing zones, tidal bays and much more. In the Canary Islands, the majority of them are night active and live on the numerous lava rocks and in caves. To see them you need a good eye, since most species are much smaller than 10cm.
Above all, the zooplankton adopt important functions. They feed on plant plankton and thus regulate plant growth. They are also an important food source for larger marine life.
Another important factor for humans is the cleaning of drinking water supplies. Crustacea filter suspended particles, bacteria, single cells and toxins to bound them.