Elephant louse
| Elephant louse | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
.jpg)
Elephant louse ( Haematomyzus elephantis ) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Haematomyzus elephantis | ||||||||||||
| Piaget , 1869 |
The elephant louse ( Haematomyzus elephantis from Greek αἷμα (haima) = blood and μύζω (myzo) = I suck) is a blood-sucking ectoparasite on elephants. Host species are both the Asian elephant and the African elephant , both of which belong to different genera.
features
Elephant lice belong to the order of animal lice and are about 2 to 2.5 mm in size. The body of the brownish colored animals is flattened dorsoventrally. They have very long legs. These have two claws on the middle and rear legs and one claw on the front legs, which are adapted for walking and do not have the special clasp function of real animal lice. The back shields ( tergites ) of the three thorax segments are fused to form a single plate without a trace of seams. The head is drawn out in a characteristic way in a trunk, which is formed from the clypeus , the genae and the postmentum ; the trunk reaches about the length of the head. At the tip of the trunk sit two small, externally strongly toothed jaws ( mandibles ). The rest of the mouthparts are transformed into a stiletto shape and serve as piercing bristles, they are retracted into the head capsule in the rest position. There are also two rather short five-part antennae on the head. The head is slightly retracted ("neck-shaped") connected to the trunk, but not movable in relation to it.
During the act of pricking, the animal digs itself into the skin with the synchronously working mandibles, with the teeth serving as an abutment. A blood vessel is then pierced with the piercing bristles. The trunk, which is hollow on the inside, serves as a suction tube with which blood is sucked in by a pump (from the cibarium ) located in the head capsule . The animal anchors itself in the skin with its trunk, it does not hold on to its legs.
Way of life and life cycle
The elephant louse is an obligatory parasite that lives on elephants and feeds monophag on the blood of its host (actually oligophagous, since the recent elephants belong to two genera). All stages of development live on the host. As is typical for lice, the eggs are stuck to hair as "nits", they sit on a small stalk. The hatching larvae resemble the adult animals both in their physique and in their way of life. Reinfection only takes place when the hosts come into physical contact, allegedly animals separated from the host should starve to death after about three hours. For nutrition, the animals are dependent on endosymbiotic enterobacteria living in their intestines , which belong to the genus Arsenophonus . The bacteria sit within specialized cells on the intestine and are passed on to the offspring via the eggs.
Elephant lice are separate sexes. The copula also takes place on the host, with the male sitting below the female.
The lice can be found on all parts of the host's skin, but prefer the head, especially the opening of the outer ear. On their host they are usually present in a relatively low density, although they are said to be more common on Asian elephants than on African elephants. They are found in all natural ranges of the various elephant species and are also regularly found on animals kept in zoos.
Systematics
The species is one of three species in the genus (the others are Haematomyzus hopkinsi on the warthog and Haematomyzus porci on the bush pig ). Haematomyzus is the only genus of the Haematomyzidae family that forms the only family of the suborder Rhynchophthirina. The animals are therefore very isolated in phylogenetic terms. In earlier times, their position in the system was therefore very controversial, and at times a separate order was even proposed for them. According to recent morphological and molecular-biological studies, the Rhynchophthirina probably form the sister group of the remaining jaw lice .
Others
Elephant lice and elephants (in principle all trunk lice and all their hosts) have a trunk. This coincidence has been noticed many times and has given rise to some mocking remarks about the workings of evolution.
supporting documents
- ↑ Eva Novakova, Václav Hypša, Nancy A. Moran (2009): Arsenophonus to emerging clade of intracellular symbionts with a broad host distribution. BMC Microbiology 9: 143 doi : 10.1186 / 1471-2180-9-143 (open access)
- ↑ CHC Lyal (2008): Phylogeny and classification of the Psocodea, with particular reference to the lice (Psocodea: Phthiraptera). Systematic Entomology 10: 145-165. doi : 10.1111 / j.1365-3113.1985.tb00525.x
- ↑ Stephen C. Barker, Michael Whiting, Kevin P. Johnson, Anna Murrell (2003): Phylogeny of the lice (Insecta, Phthiraptera) inferred from small subunit rRNA. Zoologica Scripta 32: 407-414. doi : 10.1046 / j.1463-6409.2003.00120.x
literature
- Eberhard Mey: 20th order Phthiraptera: animal lice, Lauskerfe. In: Alfred Kaestner, Holger H. Dathe (ed.): Textbook of special zoology . Volume 1: Invertebrates , Part 5: Insecta. 2nd edition, Spektrum Akademischer Verlag, Heidelberg / Berlin 2003, ISBN 3-8274-0930-6 .
