Selkäkilvestä

Selkäkilvestä refers to the dorsal carapace of certain arthropods, particularly crustaceans like crabs and lobsters, as well as some extinct marine arthropods like trilobites. It is essentially the hardened upper shell that covers and protects the back of the animal. This structure is derived from the exoskeleton, a characteristic feature of arthropods, and is formed from chitin, often reinforced with minerals like calcium carbonate, which provides rigidity and defense against predators and environmental stresses.

The shape and features of the selkäkilvestä can vary greatly depending on the species. In crabs, it is typically broad and flattened, while in lobsters, it is more elongated and segmented. In trilobites, the selkäkilvestä was divided into three longitudinal lobes, giving them their name. This carapace often bears distinctive patterns, spines, or tubercles that can be important for species identification and can also play a role in camouflage or signaling. The growth of the selkäkilvestä occurs during molting, a process where the arthropod sheds its old exoskeleton to accommodate its increasing size.