Myriapoda

Indefinite Millipedes

• Centipedes ( Chilopoda )
• Wenigfüßer ( Pauropoda )
• Zwergfüßer ( Symphyla )
• Millipedes ( Diplopoda )

The millipedes ( Myriapoda, and centipedes ) are a sub-tribe of Arthropods ( Arthropoda ), they comprise only terrestrial forms, usually with two or at most three-digit number of legs.

Sometimes the term is restricted millipedes in a narrower sense to the class of mostly herbivorous millipedes, which represent the majority of the group of about ten thousand known species. Three thousand known species include carnivorous centipede. There are also smaller groups of Zwergfüßer and Wenigfüßer.

• 3.1 Outer systematics
• 3.2 Internal systematics

Construction of the Millipedes

Millipedes have a body that is divided into two sections ( tagmata ): On a head capsule, which is composed of several fused segments, followed by a self- similar ( homonom ) articulated hull with at least four legged segments.

Head

The head capsule of the millipede wears as attachments a pair of antennae and two or three pairs of mouthparts. The antennas are antenna elements in which each element has its own muscles. The antennas of the Chilopoda and Symphyla are simple and slightly modified. The millipedes have characteristic, angled ( gekniete ) of eight segments constructed antennas whose last element has four major sense cones. The antennas of the Pauropoden are cleaved with several antenna flagella. The antenna is followed by a segment -free limbs ( Interkalarsegment ) corresponding to that of the second antenna of the crustaceans. The mouth starts with a - often toothed - upper lip ( labrum ), culminating it up, then a pair of mandibles and two pairs of maxillae. Diplopoda and Pauropoda have only one pair of maxillae which is called here Gnathochilarium. Here are either both maxillae fused, or is completely lost. The Symphyla the maxillae are quite similar. In the Chilopoda the second pair of maxillae is elongated and running leg similar. The Pauropoda the mouthparts are more or less reduced and simplified.

The construction of the mandibles is characteristic of the Millipede: The mandible is almost always in two relatively movable sections ( at the Diplopoda even three ) divided. At the Mandibelbewegung is the tentorium, involved a seated inside the head skeleton structure. Those muscles that contract the mandibles (groin ) set to not participate in the mandible itself, but on the tentorium, which forms a joint with the Mandibelbasis. It consists of two movably mounted longitudinal bars, which are connected by a crossbar. The movable, swinging tentorium occurs in no other Arthropodengruppe.

Eyes are formed in many Chilopoda and Diplopoda, while Symphyla and Pauropoda are always eyeless. The construction of the eye is quite different to each other. Many Chilopoda ( Lithobiomorpha, Scolopendromorpha except Cryptopidae, Craterostigmomorpha ) einlinsiger have a different number, button -shaped ocelli. The Scutigeromorpha have real complex eyes, but differ in their fine structure from those of insects and crustaceans. Diplopoda the complex possess eye -like eyes fields ommatidia number which are arranged in rows. When molting juvenile stages each eye row is added at each stage. The ommatidia differ in their fine structure also significantly from those of the Tetraconata (insects and crustaceans) from; in particular, they do not have a crystal cone, but instead a strongly thickened lens ( cornea). Whether you look at those eyes as modified forms, which emerged from complex eye reduction training or as a stand-alone, derived from the same basic forms of parallel developments, depends on the hypothesis on the phylogenetic relationships of millipedes.

Hull

The uniform, wearing many pairs of legs fuselage section is the most striking feature of the millipedes. In fact, the hull of the various classes of millipedes is but built differently. The body is flattened or round. On the top ( dorsal) sitting in the Chilopoda, Symphyla, and a number, often slightly overlapping the back plates ( Tergites ). In the Chilopoda follows characteristically stringing always a short and a long tergite on each other (except seventh and eighth tergite, both of which are long). The Symphyla the tergites are different, often crescent- shaped or pulled back into triangular lobes, partially reduced in some ground-dwelling forms and dissolved in two adjacent plate pairs. In some segments, they are often split across and dissolved in consecutive pairs. In the Diplopoda two consecutive segments are to a double segment fused (with two pairs of legs ), with most ( the Helminthomorpha ) the body of almost closed, and armored by the incorporation of calcium carbonate, surrounded rings that are interrupted only by the rows of legs.

Each segment bears a pair of legs each in principle. Often, however, the first and last segments are different. The first body segment of the Chilopoda is connected to the head. This segment carries powerful, referred to as maxillipeds pairs of legs, which have fangs and serve the ( predatory ) diet. In many species of the other groups, the first segment bears, however, no or greatly reduced pairs of legs. Sitting at the end of the body spread one or two segments without limbs.

The legs are either sideways ( Chilopoda ), or on the ventral side ( Diplopoda ) of the hull. The legs are named in six or seven segments coxa - trochanter - Präfemur - femur - ( Postfemur ) - Tibia - Tarsus divided. The Diplopoda have one member, the Postfemur more. Your bent legs form a knee joint -like hinge. There is also a pretarsus, sitting at the usually a single ( unpaired ) claw.

For the number of legs

As the name suggests, some millipedes species have a large number of legs - most, namely 750 legs were plenipes counted in the way Illacme. The literal centipede there is not thus. However, not all types of a high number of legs. It is the most primitive, systematically basalsten groups have relatively few pairs of legs. It is believed, therefore, that the high leg speed is not a primitive but an evolution in the later acquired feature perhaps. The question is, however, difficult to decide, since to date, no fossils of the core group millipedes were found.

The centipedes come in different groups have different development paths before:

• The hatch with their final segment ( and leg ) number from the egg ( epimorphosis ).
• When you slip, not all segments present, their number increases in growth and molting to ( anamorphosis )

In the anamorphosis there are two different ways:

• The animal eventually reaches a fixed finite number of segments. It sheds its skin then no more ( Teloanamorphose ) or at the moults the segment number remains the same ( Hemianamorphose ).
• The animal gains at each molt added segments, a fixed final number is not visible ( Euanamorphose ).

In species with Euanamorphose so there is no fixed leg number, this is different for different individuals.

Within the millipedes following groups etc. to distinguish:

• Relatively low, fixed leg number. for example, 12 pairs of legs at the Symphyla, 15 at the Scutigeromorpha and Lithobiomorpha ( Chilopoda ). The lowest occurring number is 8 at the Pauropoda (probably secondarily reduced).
• Relatively high, fixed leg number. eg 21 or 23 pairs in the Scolopendromorpha, 49 or 51 in numerous Diplopoda.
• High, non fixed leg number. Diplopods: up to 216 pairs of legs at the Platydesmida, to 380 at the Siphonophorida ( cp. Name the record holder above). Chilopods: up to 194 pairs of legs at the Geophilomorpha.

In species of the genus Scolodendropsis ( Chilopoda, Scolopendromorpha ) showed that close verwandete species have partially 21 or 23, sometimes 39 or 43 pairs of legs in the same class, here is the presumption suggests that the number of segments is doubled by a single mutation has.

The ratios are complicated by the fact that in various Myriapods the number of legs, the dorsal plates ( tergites ) and other segmental systems do not have to match. When juice Kugler Glomeris to dorsal and ventral side of the embryo develop apparently independent of each other, so that no fixed number of segments must exist, the two would be together.

Classification of millipedes

Outer systematics

Traditionally, the breathing by tracheae millipedes with the Sechsfüßern were (the main group, the insects are ) collectively Tracheentiere. However, this did not last later studies.

More recent work on the morphology, especially of the nervous system, the fine construction of the eyes and numerous phylogenetic trees (due to homologous DNA sequences ) have clearly shown that the Hexapoda represent (including insects ) and crustaceans ( Crustacea) a common lineage, the after the construction of the eyes usually " Tetraconata " is named. Thus, can not, as had been previously assumed for decades as almost certain to be the millipedes and the Hexapoda sister groups. This grouping, which according to the respiratory organs as Tracheentiere ( Tracheata, " Atelocerata " also ) had been referred previously appeared well founded according to morphological criteria. From now dozens molecular studies, comprehensive and methodologically more sophisticated, but this has not been confirmed one. The common features of millipedes and Hexapoda are therefore highly likely convergent formations that were connected mainly with the transition from water to land-living forms. If the Hexapoda therefore are not the sister group of the Myriapoda, is on the monophyly of millipedes no doubt begründbarer more. Accordingly, opposite to a some time prevailing theory of the zoologist Otto Kraus, provided by all modern editors, the monophyletic origin community of Myriapoda.

About the actual sister group relationship of millipedes exist today two hypotheses. Most scientists believe that the millipedes, the Hexapoda and Crustacea form a Mandibulata named group. This is supported by numerous morphological arguments, for example the construction of the mouthparts and the nervous system as well as a series of molecular studies. Many other molecular studies can also seem to be possible there but that actually the pine pawl carrier ( Chelicerata; mainly include arachnids ) the closest relatives of centipedes were. For this group there is ( from a special feature of the embryonic formation of the nervous system apart ) no justifiable on the morphology argument. This possible grouping is called " Myriochelata " or " Paradoxopoda ".

Hypothesis 1:

Chelicerata

Millipedes

Crustacea

Hexapoda

Hypothesis 2:

Millipedes

Chelicerata

Crustacea

Hexapoda

Internal system

The internal classification of Myriapoda is relatively well secured.

Thus, the millipede and the Wenigfüßer form the taxon Dignatha due to several well-justified characteristics. These features are a fusion of the basal members of the first maxilla to a lower lip ( Gnathocilarium ), the loss of the second maxilla or rudimentary plant the same in embryonic development, genital openings in the second segment, Tracheenöffnungen near the legs, young animal with only three pairs of legs.

The Dignatha turn form the Zwergfüßern the taxon Progoneata due to the gut and fat body formation within the yolk as well as the structure of the mechanoreceptors ( trichobothria ).

• Millipede - Myriapoda Centipedes - Chilopoda
• Progoneata Zwergfüßer - Symphyla
• Dignatha Wenigfüßer - Pauropoda
• Millipedes - Diplopoda

Millipede plagues

Occasionally, there is proliferation of centipedes, probably due to mild weather conditions and favorable food supply. Due to the massive occurrence of diplopods Megaphyllum unilineatum the inhabitants felt harassed in the Bavarian Obereichstätt. Together with the water -purpose association built the municipality has a 200 m long and 30 cm high protective wall at the edge of town.

In the community Röns in Vorarlberg, Austria, which is also haunted past 6 years every spring Megaphyllum unilineatum, the millipedes with predatory mites and diatomaceous earth be fought.

Terrarium

Millipedes, especially the larger tropical species are also often held as terrarium animals. Although they require, like all other animals also, regular care and welfare accommodation, but have the advantage of being very economical to maintain. Most species do not need live food or special lighting, usually no heating. As feed them often enough the soil substrate with halbverrottetem leaves, weißfaulem wood and occasional fruit gifts.