www.small-beings.org
www.small-beings.org
Die Krebstiere (Crustacea) oder Krebse bilden mit weltweit mindestens 52.000 rezent bekannten Arten einen Unterstamm innerhalb der Gliederfüßer (Arthropoda), die sich vor allem durch eine große Formenvielfalt, als evolutionäre Anpassung an verschiedene Lebensräume und Lebensweisen, auszeichnen. Zu Lebensmittelzwecken verwendete Krebstiere werden in der Kochkunst als Krustentiere bezeichnet.
Zusammenfassung: In diesem Text werden verschiedene Merkmale, die Fortpflanzung, Entwicklung, Lebensraum, Metabolismus, Evolution, Systematik und ökologische sowie wirtschaftliche Bedeutung der Krebse beschrieben. Krebse weisen eine große Vielfalt an Formen auf und können sowohl im Wasser als auch an Land gefunden werden. Sie spielen eine wichtige Rolle in marinen und limnischen Ökosystemen, da sie das pflanzliche Plankton regulieren und als Nahrungsquelle für andere Organismen dienen. Einige Krebsarten wie Garnelen und Hummer werden auch als Nahrungsmittel genutzt. Die Reinigung von Trinkwasserreservoiren gehört ebenfalls zu den Aufgaben der Krebse.
Crustaceans are invertebrate animals of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthropods including decapods (shrimps, prawns, crabs, lobsters and crayfish), seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, opossum shrimps, amphipods and mantis shrimp. The crustacean group can be treated as a subphylum under the clade Mandibulata. It is now well accepted that the hexapods (insects and entognathans) emerged deep in the Crustacean group, with the completed group referred to as Pancrustacea. The three classes Cephalocarida, Branchiopoda and Remipedia are more closely related to the hexapods than they are to any of the other crustaceans (oligostracans and multicrustaceans).The 67,000 described species range in size from Stygotantulus stocki at 0.1 mm (0.004 in), to the Japanese spider crab with a leg span of up to 3.8 m (12.5 ft) and a mass of 20 kg (44 lb). Like other arthropods, crustaceans have an exoskeleton, which they moult to grow. They are distinguished from other groups of arthropods, such as insects, myriapods and chelicerates, by the possession of biramous (two-parted) limbs, and by their larval forms, such as the nauplius stage of branchiopods and copepods. Most crustaceans are free-living aquatic animals, but some are terrestrial (e.g. woodlice, sandhoppers), some are parasitic (e.g. Rhizocephala, fish lice, tongue worms) and some are sessile (e.g. barnacles). The group has an extensive fossil record, reaching back to the Cambrian. More than 7.9 million tons of crustaceans per year are harvested by fishery or farming for human consumption, consisting mostly of shrimp and prawns. Krill and copepods are not as widely fished, but may be the animals with the greatest biomass on the planet, and form a vital part of the food chain. The scientific study of crustaceans is known as carcinology (alternatively, malacostracology, crustaceology or crustalogy), and a scientist who works in carcinology is a carcinologist.
This summary provides an overview of crustaceans, focusing on their structure, ecology, classification, fossil record, and consumption by humans. Crustaceans have bodies composed of segments, including the head, thorax, and abdomen, and are protected by a hard exoskeleton. They are primarily aquatic, but some species have adapted to life on land. The classification of crustaceans is complex and includes various classes such as Branchiopoda, Maxillopoda, and Malacostraca. They have a diverse fossil record, with major groups appearing as early as the Cambrian period. Many crustaceans, particularly decapods like crabs and shrimp, are consumed by humans.