Spinicaudata
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Limnadia lenticularis |
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| Spinicaudata | ||||||||||||
| Linder , 1945 | ||||||||||||
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The Spinicaudata represent an order or subordination of the clawed tails (Onychura) within the leaf crabs (Branchiopoda). Around 180 species of the Spinicaudata are known worldwide.
Spinicaudates live mainly on the bottom and in the mud of small bodies of water that regularly dry out, only the species Cyclestheira hislopi is found in the open water of larger lakes in the tropics.
Construction of the Spinicaudata
Spinicaudates usually reach body lengths of over 10 millimeters. Like almost all members of the clawed tail, the body of the animals is surrounded by a two-lobed shell ( carapace ) from which only the second antennae, developed into swimming legs, and a small part of the last segment ( telson ) protrude. The skinning stripes on the shell are noticeable, which are caused by the fact that the carapace is not skinned with the rest of the body. The shell is held together by a strong sphincter muscle. The short body of the animals is only fused with the carapace at the back of the head.
The body of the Spinicaudata consists of a maximum of 32 segments. Each segment has a pair of leaf legs, the original structure of which is difficult to see. The oar stroke of the legs creates a stream of water that transports oxygen and nutrient-rich water into the centrally located food channel and to the gills. Food particles are filtered out by bristles and transported forward to the mouth opening.
The 1st antenna is movable and usually finger-shaped and equipped with a long sensory bristle, the 2nd antenna is very strong and has two branches and serves as a swimming leg. For this reason, she also has numerous floating bristles. All Spinicaudates have a pair of compound eyes , which in the species Cyclestheira hislopi is fused in the middle.
Reproduction and development
Reproduction in some species of Spinicaudata can be parthenogenic , but predominantly it is bisexual. In the males, the first two leaf bones have been transformed into grasping organs with which they can hold the females for copulation.
The female attaches the eggs in large egg balls to the 9th to 12th pairs of legs and releases them during the next molt. In Cyclestheira hislopi , the eggs are carried in the shell until they hatch in the brood chamber. The eggs are drought-resistant and can survive for some time in dry soil. Nauplius larvae hatch from the eggs and retain the characteristics of adults through several moults.
Systematics of the Spinicaudata
The Spinicaudata used to be grouped together with the Laevicaudata to form the Conchostraca, but this group is very likely not a natural unit. According to various authors, the species Cyclestheira hislopi is also relocated from the Spinicaudata and placed in the vicinity of other groups of the clawed tails .
The Spinicaudata contain the following families:
- Leptestheriidae (in Central Europe for example Leptestheria dahalacensis )
- Cyzicidae (in Central Europe for example Cyzcus tetracerus )
- Limnadiidae (in Central Europe for example Limnadia lenticularis )
- Cyclestheriidae (only species Cyclestheira hislopi in tropical lakes)
literature
- Ax P. (1999): The system of the Metazoa II. A textbook on phylogenetic systematics. ; Gustav Fischer Verlag.
- Gruner HE (1993): Class Crustacea. In: Gruner HE (Hrsg.): Textbook of Special Zoology. Volume I, 4th part: Arthropoda (without Insecta) "; Gustav Fischer Verlag
- Schminke HK (1997): Crustacea, Krebse. In: Westheide, Rieger (Ed.): Special Zoology Part 1: Protozoa and invertebrates. Gustav Fischer Verlag
