#starfish

• Actinomere — An anatomical segment or structural zone within a body exhibiting radial symmetry, corresponding to one of the repetitive sections arranged around the central axis. In invertebrate zoology, the term describes each of the similar radial segments making up the body of certain echinoderms (such as the arms of starfish) or coelenterates, including the internal organs and skeletal structures associated with that section.
• Ambulacral — Belonging to the ambulacrum, relating to the ambulacrum or to the water vascular system of echinoderms (such as starfish or sea urchins). The term describes anatomical elements, perforated zones of the exoskeleton, or flexible hydraulic feet utilized by these marine organisms for locomotion, fixation, respiration, and food capture in their natural environment.
• Asterid — An unofficial or regional singular form derived from the class name Asteroidea, used to designate an individual belonging to the starfish group; alternatively, in modern systematic botany, the term (in its plural form, asterids) denotes a large phylogenetic clade of flowering dicotyledonous plants, grouping orders such as Solanales, Lamiales, or Asterales.
• Astérie — An old popular name or rare lexical regionalism used in isolation to name the starfish (a marine invertebrate of the Asteroidea class); the term represents a direct adaptation of the noun from the French language ('astérie') or classical Latin, preserved in old 19th-century natural history translations.
• Asteroidea — A major taxonomic class of marine invertebrates in the phylum Echinodermata, grouping all true species of starfish; they are characterized by a flat central disc body from which multiple radiate arms (typically five) extend symmetrically, covered by a calcareous exoskeleton and equipped with tube feet for locomotion.
• Asterozoans — A major subphylum or taxonomic grouping (Asterozoa) within the phylum Echinodermata, bringing together all echinoderms with a star-shaped body and unchanging radial symmetry; it includes two major extant classes: Asteroidea (true starfish) and Ophiuroidea (brittle stars or ophiuroids).