#arthropods

• Acanthopodous — A scholarly morphological term used as an adjective to describe an organism, arthropod, or anatomical structure whose limbs, legs, or locomotory appendages are equipped with spines, rigid thorns, or rows of sharp spikes. As a masculine noun, it defines a locomotory limb structurally modified through the development of such prickly elements, an adaptation found in certain predatory insects (such as some mantis or orthopteran species) used for efficiently capturing and immobilizing prey.
• Apodemes — Internal ingrowths or ridges of the arthropod exoskeleton that serve as structural supports and provide solid points of attachment and leverage for locomotory muscles; internal cuticular projections. These chitinous formations fulfill the function of a functional endoschelet, being essential for the biomechanics of insect and crustacean movement.
• Arachnid — An alternative spelling variant for arahnidă (arachnid); any arthropod invertebrate belonging to the class Arachnida, characterized by a body divided into two distinct regions (prosoma and opisthosoma), the lack of antennae and wings, the presence of chelicerae and pedipalps, and exactly four pairs of articulated walking legs. As an adjective, it describes any anatomical, biological, or behavioral trait pertaining to this massive group which includes spiders, scorpions, ticks, and harvestmen.
• Arachnids — An alternative spelling variant for arahnide (arachnids); a major class of terrestrial or aquatic chelicerate arthropods, characterized by a body segmented into a cephalothorax and abdomen, the lack of antennae, the presence of two pairs of mouth appendages (chelicerae and pedipalps), and exactly eight articulated legs. The class includes spiders, scorpions, harvestmen, mites, and ticks, playing a vital ecological role as insect predators.
• Arachnid — Any arthropod invertebrate belonging to the class Arachnida, characterized by a body divided into two distinct regions named cephalothorax (prosoma) and abdomen (opisthosoma), the total lack of antennae and wings, the presence of chelicerae and pedipalps as mouth appendages, and exactly eight articulated legs destined for terrestrial locomotion. As an adjective, it describes any structural, biological, or behavioral trait specific to this vast group including spiders, scorpions, ticks, and harvestmen.
• Arachnid — Any arthropod invertebrate belonging to the class Arachnida, characterized by a body divided into two distinct regions, the cephalothorax and abdomen, the total lack of antennae and wings, the presence of chelicerae and pedipalps, and exactly eight articulated walking legs. The term defines both scientifically and popularly the members of a vast and adaptable group of terrestrial predators or parasites, including spiders, scorpions, mites, and ticks.
• Primitive arthropods — An archaic or very rare taxonomic term used to denote a primitive group of insects characterized by rudimentary articulated legs or ancestral abdominal appendages. In evolutionary biology works of the past century, the term referred to hypothetical or fossil intermediate forms explaining the morphological transition from early arthropods to modern winged insects.
• Arthropods — The scientific and taxonomic designation assigned to the largest phylum of invertebrate animals (Arthropoda), consisting of species with a segmented body, bilateral symmetry, and jointed appendages. Members of this group, which inhabit absolutely all living environments on the planet, periodically undergo the molting process to allow body growth restricted by the external crust.