Pteriomorphia
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Pectinide clam |
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| Beurlen , 1944 |
The pteriomorphia ( wing-shaped ) are a large group of mussels (bivalvia), which in the newer classifications is listed as a partial or infra-class within the autolamellibranchiata . It is a large group of mussels found almost exclusively in the sea. It is considered the sister group of the Heteroconchia ( Heterodonta + Palaeoheterodonta ). The oldest pteriomorphia are already known from the Lower Ordovician .
characterization
The housings of the pteriomorphia are mostly equilateral to slightly unevenly hinged. The oysters (Ostreida) included in the large group have irregular shells that are firmly cemented to the substrate. The bowls are originally aragonitic; In several groups, however, shell layers made of calcite crystals are built up. The lock is diverse, the sphincters are uniform, irregular and z. Sometimes even reduced to a muscle. The foot is usually well developed, and in some taxa it can be reduced. It is usually used for digging, crawling and, more rarely, for drilling.
Way of life
The Pteriomorphia are almost exclusively marine mussels. Attachment to the substrate with the help of organic byssus is very common within the group . Within the Limida there are free-living forms that can swim with the help of the recoil principle.
Systematics
The pteriomorphia are considered in the cladistics as the sister group of the heteroconchia. The subdivision of the pteriomorphia according to the latest classification by Bieler & Mikkelsen (2006) includes five orders. Most other authors add a sixth order. In addition, there are two exclusively fossil orders that Bieler & Mikkelsen (2006) do not consider. Pteriomorphia Beurlen, 1944
- Order Arcida STOLICZKA , 1870
- Order Mytilida FÉRUSSAC , 1822
- Order Pteriida NEWELL , 1965
- Order Limida Waller, 1978
- Order Pectinida ADAMS & ADAMS , 1857 (not generally recognized)
- Order Ostreida FÉRUSSAC, 1822 (this order is "degraded" by Bieler et al. (2006) to a superfamily and assigned to the order Pteriida Newell.).
- Order † Praecardioida NEWELL, 1965
- Order † Cyrtodontoida Scarlato & Starobogatov, 1971.
Other authors subdivide the subclass into three groups: Isofilibranchia (Ord. Mytilida ), Prionodonta (Orders Cyrtodonta and Arcida ) and Eupteriomorphia (Orders Pteroida , Limida , Ostreida , Pectinida ).
literature
- Michael Amler, Rudolf Fischer & Nicole Rogalla: Mussels . Haeckel library, volume 5. Enke Verlag, Stuttgart 2000 ISBN 3-13-118391-8 .
- Rüdiger Bieler & Paula M. Mikkelsen: Bivalvia - a look at the branches . Zoological Journal of the Linnean Society, 148: 223-235, London 2006.
