Arthropod | Definition, Examples, Characteristics, Classes, Groups ...
2024年12月16日 · Arthropod, any member of the phylum Arthropoda, the largest phylum in the animal kingdom, which includes such familiar forms as lobsters, crabs, spiders, mites, insects, centipedes, and millipedes. About 84 percent of all known species of animals are members of this phylum. Learn more about arthropods in this article.
Arthropod - Exoskeleton, Segmented, Jointed | Britannica
2024年12月16日 · Arthropod - Exoskeleton, Segmented, Jointed: Most arthropods are small animals; only aquatic forms can attain substantial sizes. The numbers and diversity of arthropods are enormous and they are found in almost all of the habitats that cover the Earth's surface. Arthropods are of great importance to humans in the form of food, medicine, and agriculture, …
Arthropod structure and classification | Britannica
arthropod, Any member of the largest phylum, Arthropoda, in the animal kingdom. Arthropoda consists of more than one million known invertebrate species in four subphyla: Uniramia (five classes, including insects), Chelicerata (three classes, including arachnids and horseshoe crabs), Crustacea (crustaceans), and Trilobita (trilobites). All arthropods are bilaterally symmetrical …
Arthropod - Evolution, Paleontology, Adaptation | Britannica
2024年12月16日 · Arthropod - Evolution, Paleontology, Adaptation: Arthropods share many features with annelids. Both groups are segmented and have similar nervous systems. Arthropods first appeared in the Cambrian and were represented by trilobites, merostomes, crustaceans, and enigmatic arthropods that do not fit into any existing subphyla. Trilobites, chelicerates, …
Arthropod - Insects, Crustaceans, Arachnids | Britannica
2024年12月16日 · Arthropod - Insects, Crustaceans, Arachnids: Arthropod classes are based on criteria such as modification, specialization, number, and appearance of body segments and appendages. Their relationships both within the phylum and with other animal phyla are uncertain. Phylum Arthropoda consists of the subphyla Chelicerata, Crustacea, Myriapoda, Hexapoda, …
Nervous system - Arthropods, Reflexes, Sensory | Britannica
2025年1月15日 · Nervous system - Arthropods, Reflexes, Sensory: The other complex compartmentalized nervous system is found in arthropods. The arthropodan brain consists of three main regions: the protocerebrum, deutocerebrum, and tritocerebrum. The anterior protocerebrum, which receives the nerves of the eyes and other organs, contains centres, or …
arthropod - Kids | Britannica Kids | Homework Help
Arthropods are animals that have a hard outside covering called an exoskeleton. Insects, crustaceans, and arachnids are three of the largest arthropod groups. Arachnids…
Muscle - Arthropods, Contraction, Movement | Britannica
2024年12月13日 · Muscle - Arthropods, Contraction, Movement: Arthropoda is the largest phylum of invertebrate animals and comprises crustaceans, insects, arachnids (spiders and scorpions), and other classes. Some arthropods have soft-bodied young stages in which the principle of the hydrostatic skeleton is important. Most adult arthropods are encased in a skeleton with jointed …
Arthropod - Nerves, Sensory Organs | Britannica
2024年12月16日 · The small size of the muscles prohibits such an organization in arthropods. Instead, the state of contraction of an arthropod muscle is determined by which of several different types of neurons supplying one muscle cell are fired. The sense organs (sensilla) on the body surface involve some specialization of the exoskeleton barrier.
Arthropod - Exoskeleton, Metabolism, Respiration | Britannica
2024年12月16日 · Arthropod - Exoskeleton, Metabolism, Respiration: Crustaceans and arachnids have paired excretory organs that open at the bases of certain appendages; myriapods, insects, and some arachnids have Malpighian tubules that open into the intestine. Both arachnids and insects possess waxy compounds in the epicuticle that reduce water loss. Insects and spiders …