AP BIOLOGY

Detailed explanation-1: -Answer: An arthropod is an invertebrate animal having an exoskeleton made up of a rigid chitinous body, a segmented body (having external segmentation) and jointed appendages.

Detailed explanation-2: -The exoskeleton is composed of a thin, outer protein layer, the epicuticle, and a thick, inner, chitin–protein layer, the procuticle. In most terrestrial arthropods, such as insects and spiders, the epicuticle contains waxes that aid in reducing evaporative water loss.

Detailed explanation-3: -Proportion of species in the kingdom Animalia, which are arthropods versus all other animals. The vast majority of arthropods are insects. The phylum Arthropoda contains a wide diversity of animals with hard exoskeletons and jointed appendages.

Detailed explanation-4: -The exoskeleton (shared with other arthropods) provides protection against predation and desiccation or water-logging (necessary for small organisms) and innumerable points of muscle attachment (for flexibility). However, the exoskeleton also limits the size that can be attained by arthropods.

Detailed explanation-5: -Beyond support, the exoskeleton provides protection against predators and strength against prey. And it protects arthropods from the environment, for example, keeping ocean-dwellers from being affected by small changes in saltiness and preventing land-dwellers from drying out.