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Discarded exoskeleton of dragonfly nymph Exoskeleton of cicada attached to a Tridax procumbens (colloquially known as the tridax daisy)An exoskeleton (from Greek έξω éxō "outer" [1] and σκελετός skeletós "skeleton" [2] [3]) is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs ...
Armour, although all used for the sole intent to ward off attackers, can be split into defensive and offensive armour. Examples of offensive armour are horns, hooves, antlers, claws and beaks, clubs and pincers, as developed in some mammals, birds, reptiles (including dinosaurs, such as the dromaeosaurid claw and the ceratopsian horn) and arthropods.
A skeleton is the structural frame that supports the body of most animals.There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal frame to which the organs and soft tissues attach; and the hydroskeleton, a flexible internal structure supported by the hydrostatic pressure of body fluids.
The exoskeleton cannot stretch and thus restricts growth. Arthropods, therefore, replace their exoskeletons by undergoing ecdysis (moulting), or shedding the old exoskeleton, the exuviae, after growing a new one that is not yet hardened. Moulting cycles run nearly continuously until an arthropod reaches full size.
The first three digits of both manus (fore foot) and pes (hind foot) are armed with horny claws, which also belong to the epidermal part of the exoskeleton. The dermal exoskeleton consists of bony scutes known as osteoderms that underlie the epidermal scales of the dorsal surface of the trunk and anterior part of the tail. The overlying scales ...
Second, most lepidosaurs have the ability to autotomize their tails. However, this trait has been lost on some recent species. In lizards and rhynchocephalians, fracture planes are present within the vertebrae of the tail that allow for its removal. Some lizards have multiple fracture planes, while others just have a single fracture plane.
Lizard is the common name used for all squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, [1] ranging across all continents except Antarctica, as well as most oceanic island chains. The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other ...
Lepidosauromorpha (in PhyloCode known as Pan-Lepidosauria [2] [3]) is a group of reptiles comprising all diapsids closer to lizards than to archosaurs (which include crocodiles and birds). The only living sub-group is the Lepidosauria , which contains two subdivisions, Squamata , which contains lizards and snakes , and Rhynchocephalia , the ...