Arthropod Animal
An Arthropod Animal is an Protostome that is invertebrate animal having an exoskeleton (a segmented body) and paired jointed appendages).
- Context:
- It can (typically) be found in nearly every habitat on Earth, from deep oceans to high mountains.
- It can (often) include insects, which are the most diverse group within Arthropoda.
- It can range from being a crustacean like crabs and lobsters to an arachnid like spiders and scorpions.
- It can exhibit various adaptations, such as wings for flight in insects, gills for underwater respiration in crustaceans, and venomous fangs in some arachnids.
- It can play crucial roles in ecosystems as pollinators, decomposers, predators, and prey.
- It can have a significant impact on human life, including agriculture, medicine, and industry.
- It can have a body divided into segments, each with a pair of jointed appendages.
- It can possess an exoskeleton made of chitin, providing protection and support.
- ...
- Example(s):
- a Marine Arthropod, such as:
- a Trilobite
- a Crustacean, such as a Decapoda, such as a crab
- a Horseshoe Crab
- a Lobster, a crustacean found in marine environments and valued as seafood
- an Insect, such as:
- a Honeybee, known for its role in pollination and honey production
- a Fly Animal
- an Ant
- a Butterfly, known for its colorful wings and metamorphic life cycle
- an Arachnid, such as:
- a Myriapod, such as:
- a Terrestrial Crustacean, such as:
- a Woodlouse, a crustacean that lives on land and is known for its ability to roll into a ball for protection
- ...
- a Marine Arthropod, such as:
- Counter-Example(s):
- Mollusks, which have soft bodies and often a hard shell but lack jointed appendages and an exoskeleton.
- Annelids, segmented worms that lack the hard exoskeleton and jointed limbs of arthropods.
- Vertebrates, animals with a backbone, contrasting with the invertebrate nature of arthropods.
- Nematodes.
- See: Livestock, Cambrian, Fortunian, Trilobite, Stylonurus, Scorpion, Crab, Centipede, Butterfly, Dinocaridida, Radiodonta.
References
2021
- (Wikipedia, 2021) ⇒ https://en.wikipedia.org/wiki/Arthropod Retrieved:2021-2-6.
- An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda, [1] which includes insects, arachnids, myriapods, and crustaceans. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora.
Arthropods are distinguished by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Arthropods are bilaterally symmetrical and their body possesses an external skeleton. Some species have wings.
Their versatility has enabled arthropods to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80 percent of all described living animal species, some of which, unlike most other animals, are very successful in dry environments. Arthropods range in size from the microscopic crustacean Stygotantulus up to the Japanese spider crab.
An arthropod's primary internal cavity is a haemocoel, which accommodates its interior organs, and through which its haemolymph – analogue of blood – circulates; it has an open circulatory system. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. Their nervous system is "ladder-like", with paired ventral nerve cords running through all segments and forming paired ganglia in each segment. Their heads are formed by fusion of varying numbers of segments, and their brains are formed by fusion of the ganglia of these segments and encircle the esophagus. The respiratory and excretory systems of arthropods vary, depending as much on their environment as on the subphylum to which they belong.
Their vision relies on various combinations of compound eyes and pigment-pit ocelli: in most species the ocelli can only detect the direction from which light is coming, and the compound eyes are the main source of information, but the main eyes of spiders are ocelli that can form images and, in a few cases, can swivel to track prey. Arthropods also have a wide range of chemical and mechanical sensors, mostly based on modifications of the many bristles known as setae that project through their cuticles.
Arthropods' methods of reproduction and development are diverse; all terrestrial species use internal fertilization, but this is often by indirect transfer of the sperm via an appendage or the ground, rather than by direct injection. Aquatic species use either internal or external fertilization. Almost all arthropods lay eggs, but scorpions give birth to live young after the eggs have hatched inside the mother. Arthropod hatchlings vary from miniature adults to grubs and caterpillars that lack jointed limbs and eventually undergo a total metamorphosis to produce the adult form. The level of maternal care for hatchlings varies from nonexistent to the prolonged care provided by scorpions.
The evolutionary ancestry of arthropods dates back to the Cambrian period. The group is generally regarded as monophyletic, and many analyses support the placement of arthropods with cycloneuralians (or their constituent clades) in a superphylum Ecdysozoa. Overall, however, the basal relationships of animals are not yet well resolved. Likewise, the relationships between various arthropod groups are still actively debated.
Arthropods contribute to the human food supply both directly as food, and more importantly indirectly as pollinators of crops. Some species are known to spread severe disease to humans, livestock, and crops.
- An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda, [1] which includes insects, arachnids, myriapods, and crustaceans. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora.
- ↑ Reference showing that Euarthropoda is a phylum: