Notostraca
The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, Triops and Lepidurus, are considered living fossils, with similar forms having existed since the end of the Devonian, around 360 million years ago. They have a broad, flat carapace, which conceals the head and bears a single pair of compound eyes. The abdomen is long, appears to be segmented and bears numerous pairs of flattened legs. The telson is flanked by a pair of long, thin caudal rami. Phenotypic plasticity within taxa makes species-level ide
Species
shield shrimp
ORDER
- KingdomAnimalia
- PhylumArthropoda
- ClassBranchiopoda
- OrderNotostraca
Habitatfreshwater
Die Notostraca, gelegentlich Rückenschaler, oder Urzeit-Krebse genannt, sind eine artenarme Ordnung der Blattfußkrebse. Rezent leben nur zwei Gattungen, Triops und Lepidurus, beide sind Spezialisten in nur kurzzeitig wasserführenden, austrocknenden (genannt: ephemeren) stehenden Gewässern des Süßwassers oder seltener Brackwassers. Funde von fossilen Notostraca zeigen eine seit 360 Millionen Jahren nahezu unveränderte Morphologie der Gruppe, die deshalb zu den „lebenden Fossilien“ gerechnet werden.[1] Inhaltsverzeichnis 1 Morphologie 1.1 Kopfabschnitt und Carapax 1.2 Rumpfabschnitt und Hinterleib 2 Fortpflanzung und Entwicklung 3 Biologie und Lebensweise 4 Phylogenie und Systematik 5 Literatur und Quellen 6 Einzelnachweise Morphologie Notostraca sind relativ große Blattfußkrebse, die Länge des Carapax erreicht etwa 15 bis 30 Millimeter. Die Gesamtlänge des Körpers ist kaum sicher anzugeben, da die Segmente des Hinterleibs im Leben gedehnt oder teleskopartig ineinander geschoben werden können, die Länge ist auch innerhalb der Arten je nach Lebensumständen hoch variabel, es werden meist Längen von 30 bis 50, im Maximum 100 Millimeter angegeben. Auch die Färbung der Tiere ist extrem va
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Article
11 sectionsContents
- Description
- Life cycle
- Ecology and distribution
- Evolution and fossil record
- Taxonomy
- Genera list
- Extant
- Extinct
- See also
- References
- External links
The order Notostraca, containing the single family Triopsidae, is a group of crustaceans known as tadpole shrimp or shield shrimp. The two genera, Triops and Lepidurus, are considered living fossils, with similar forms having existed since the end of the Devonian, around 360 million years ago. They have a broad, flat carapace, which conceals the head and bears a single pair of compound eyes. The abdomen is long, appears to be segmented and bears numerous pairs of flattened legs. The telson is flanked by a pair of long, thin caudal rami. Phenotypic plasticity within taxa makes species-level identification difficult, and is further compounded by variation in the mode of reproduction. Notostracans are omnivores living on the bottom of temporary pools and shallow lakes.
==Description== Notostracans are long, with a broad carapace at the front end, and a long, slender abdomen. This gives them a similar overall shape to a tadpole, from which the common name tadpole shrimp derives. The carapace is dorso-ventrally flattened, smooth, and bears no rostrum; it includes the head, and the two sessile compound eyes are located together on top of the head. The two pairs of antennae are much reduced, with the second pair sometimes missing altogether. The mouthparts comprise a pair of uniramous mandibles and no maxillipeds.
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Cisuralian taxonomic ordersCrustacean ordersEarly Cretaceous taxonomic ordersEarly Jurassic taxonomic ordersEarly Triassic taxonomic ordersEocene taxonomic ordersExtant Carboniferous first appearancesFreshwater crustaceansGuadalupian taxonomic ordersHolocene taxonomic ordersLate Cretaceous taxonomic ordersLate Jurassic taxonomic orders