Midget ( Symphyla )
|Ryder , 1880|
The pygmy pods (Symphyla) are a class of the arthropods (Arthropoda) and are classified among the millipedes (Myriapoda). Around 150 species of these very small, pigmentless and eyeless animals are known worldwide. They are a maximum of 9 mm long.
Way of life of the dwarf pods
The dwarf pods live mainly in the uppermost soil layer ( mulm ), under dung heaps and under stones. They feed on rotting and also living parts of plants. If they occur in large numbers, they can act as pests , especially in garden centers (including greenhouses) .
Dwarf dwarf burrow
Like all members of the Myriapods, the pygmy pods are characterized by a uniform structure of the body segments. The pygmy pods always have 12 segments, each carrying a pair of legs. If you look at them from above, you can often see more than 12 back plates ( 15 for Scutigerella , otherwise up to 25), as some segments form two of these structures, known as tergites. The legs are built uniformly, only the first pair of legs can have fewer limbs or be completely absent. On the legs 2 - 12 the animals have fold-out sacs ( coxal organs ), on the legs 3 - 12 additional pen-like structures ( styli ).
The head of the animals is flat and has several flat mouthparts ( mandibles and two pairs of maxillae ) on the underside . The second pair of maxilla forms a lower lip. The antennas are made up of a chain of similar antenna links and form a so-called link antenna. Unlike all other tracheal animals , the pygmy pods have only a single pair of tracheal openings ( stigmas ) near the base of the mandible, from where branched tracheas extend into the 4th trunk segment.
The rear end carries a pair of spinning pens that are connected to spinneret glands in the body, as well as a pair of mechanoreceptors ( trichobothria ).
Reproduction and development
For mating, the male of the pygmy pygmy (observed in Scutigerella ) forms a long secretion stalk on which it deposits a sperm drop. This drop is taken up by the females and stored in the vestibule. Then it deposits the eggs one by one on the leaves of moss and fertilizes them there with the help of the sperm store.
The pygmy pygmy pups hatch with a significantly reduced number of legs ( Scutigerella with seven pairs of legs) and are given a new pair of legs with each moult until all segments are present. Even then, the animals continue to molt.
Systematics of the dwarf pods
The centipedes form due to the intestinal and body fat formation within the yolk, as well as the structure of the mechanoreceptors (trichobothria) together with the Dignatha ( millipedes and pauropoda ) taxon Progoneata. This group is usually compared to the centipedes as a sister group.
The European species of pygmy pygmy are divided into two families, the Scolopendrellidae (for example with Symphylella vulgaris ) and the Scutigerellidae (with Scutigerella immaculata , S. tusca , S. pagesi , S. remyi and S. silvatica ). Fossils are now known from both families. A representative of the genus Scolopendrella from the Baltic amber is the only fossil scolopendrellid. Within the Scutigerellid, two species from Baltic amber and one from Dominican amber are known.
- Wolfgang Dohle : Progoneata , in: W. Westheide, R. Rieger (Ed.): “ Special Zoology Part 1: Protozoa and Invertebrates ”; Gustav Fischer Verlag, Stuttgart, Jena 1996; Pages 592-600
- George O. Poinar, Jr .: Life in Amber . 350 p., 147 fig., 10 plates, Stanford University Press, Stanford (Cal.) 1992. ISBN 0-8047-2001-0 with reference to A. Bachofen-Echt: Ueber die Myriapoden des Bernsteins. In Palaeobiologica 7 , 1942; A. Bachofen-Echt: Amber and its inclusions. Vienna, 1949
- Scheller, U. & J. Wunderlich (2004): Two fossil symphylan species, Scutigerella baltica n. Sp. and Hanseniella baltica n. sp. (Tracheata, Scutigerellidae), in Baltic amber. - Stuttgart Contributions to Natural History Series B (Geology and Paleontology) 351: 1–11
- Poinar, GO & CA Edwards (1995): First description of a fossil symphylan, Scutigerella dominicana sp. n. (Scutigerellidae, Symphyla), in Dominican amber. - Experientia 51: 391-393