#spines

• Acanthiferous — An anatomical and zoological term used to describe an organism, organ, or anatomical structure that is covered with spines, thorns, or sharp rigid formations, or that bears such defensive elements. In taxonomy and paleontology, this adjective serves as an essential morphological criterion for describing and classifying certain marine invertebrate species (such as radiolarians or some bryozoans) or fossil reptiles whose exoskeletons or shells are equipped with spiny extensions.
• Acanthophilous — A plant morphological term used as an adjective to describe a plant displaying a strong ecological affinity for environments populated by spiny species, or whose leaves have partially or completely transformed into spines or thorns (a typical adaptation to drought). As a masculine noun, it defines a foliar anatomical structure evolutionarily modified into a sharp, rigid needle (as seen in cactus leaves or certain acacia species), serving to reduce water loss via transpiration and ensure self-defense.
• Acanthophorous — A scholarly morphological term used as an adjective to describe an organism, organ, or anatomical structure equipped with spine-bearing elements, thorns, or sharp rigid protrusions. As a masculine noun, it defines a skeletal part, an appendage, or a specialized cuticular zone that supports or bears a defensive spine (frequently encountered in the exoskeleton structure of some marine crustaceans, bryozoans, or fossil fishes from the Paleozoic era).
• Acanthology — A specialized branch or treatise within the biological sciences (botany and zoology) that deals with the systematic study, classification, anatomical structure, and ecological role of spines, thorns, prickles, or sharp rigid formations present in plants and animals. The term governs research focused on the defensive and adaptive morphological modifications of xerophytic organisms or invertebrates and vertebrates armed with spikes.
• Acrocomia — A genus of monocotyledonous plants in the palm family (Arecaceae), native to tropical and subtropical regions of Central and South America. These palms are characterized by massive trunks covered with sharp spines and dense crowns of pinnate leaves.
• Actinacanth — A zoological term used to describe an organism, an anatomical structure, or a skeletal element provided with spines, spicules, or sharp extensions arranged in a radiating manner. In the context of paleontology and aquatic taxonomy, it specifically describes the morphology of certain radiolarians, sponges, or ancient marine fauna whose rigid support elements emerge from a common center in the shape of stinging rays.
• Ancistrocactus — A genus of succulent plants in the family Cactaceae, native to the arid and semi-desert regions of the southern United States (Texas) and northern Mexico. It comprises relatively small, globular to cylindrical cacti with well-defined ribs and areoles bearing strong central spines, at least one of which is long and sharply hooked, a morphological feature that gives the genus its name.
• Hedgehog — A small insectivorous mammal (Erinaceus europaeus) with a pointed snout and its back covered with long, rigid spines, which rolls into a ball when endangered as a structural self-defense mechanism. In a technical or military sense, the term denotes a defensive obstacle made of crossed beams (Czech hedgehog) used as an anti-tank barrier, an industrial part equipped with protruding teeth, or a stiff cylindrical brush used for cleaning chimneys.
• Astrophytum capricorne — A species of xerophytic plants within the Astrophytum genus (Cactaceae family), native to the semi-desert regions of Mexico (Chihuahuan Desert), characterized by a spherical stem that becomes cylindrical at maturity, divided into 7-8 sharp ribs. The species is distinguished by its long, flexible, flattened, and twisted spines reminiscent of a goat's horns (or a capricorn's), and by its large, yellow flowers with a deep purple or red center.
• Aylostera spinosissima — A perennial species of dwarf cactus native to the mountainous and arid regions of Bolivia, structurally recognized by its dark green globose or short cylindrical stems, characterized by an amazing density of long, thin, and extremely rigid spines. Its specific epithet originates from Latin, meaning 'most thorny', reflecting this dense protective shield from which spectacular, deep brick-red funnel-shaped flowers erupt delicately in spring from the lower areoles.