Arthropods

from greek: arthron (joint) and pous (foot)
German: Gliederfüßer

1 Definition

Arthropods are a phylum of the animal kingdom. They are invertebrates with a chitinous exoskeleton and characteristically sectioned body segments and legs. Some species are of medical relevance since they can act as vectors (transmitters of infections), parasites or be poisonous.

2 Classification

The taxonomy of arthropods is, especially with regards to molecular biological aspects, subject to constant alterations. That is why the following listing of the most important groups (taxa) of arthropods does not have any claim to completeness or accuracy with regard to the latest revisions of zoological research.

2.1 Internal Classification

Internal classification according to Pschyrembel - Klinisches Wörterbuch (261. edition), including the most important characteristics:

• Phylum: Arthropoda
  • Subphylum: Crustacea
    • The body is made up of 3 pieces (caput, thorax, abdomen)
    • two pair of antennas
    • breathing under water with gills
  • Subphylum: Chelicerata
    • The body is sectioned into the cephalothorax and abdomen
    • 4 pairs of legs
    • breathing air with trachea, lung
    • most important subgroup: arachnids
  • Subphylum: Myriapoda
    • The body is made up of a caput and trunk of at least 4 segments
  • Subphylum: Hexapoda (insects)
    • The body consists of caput, thorax and abdomen
    • Thorax with 3 pair of legs
    • one pair of antennas

3 Medical relevances

• Crustaceans: Can be Intermediate hosts, i.e. crabs for lung leeches (paragonimidae, paragonimiasis).

Pentastomida are parasites that inhabit the respiratory tracts of certain vertebrate animals.

• Crustaceans: Some scorpions and spiders are capable of injecting toxins into the blood circulation of humans (i.e. deathstalker, black widow).

Numerous mites are ectoparasites and are considered to be vectors of diseases (i.e. ticks transmistting tick-borne encephalitis (TBE) or lyme disease).

• Myriapoda: Some species produce toxins that act, depending on species, as contact poison or can be introduced to the bloodstream of pray or potential enemys.
• Insects: Insects can be parasites and vectors (sometimes at the same time), i.e. human flea, mosquito, bedbugs, lice.

Other insects are poisonous animals such as wasps and bees.

4 Homeopathic agents

Some arthropods or parts of them are being used for the manufacturing of homeopathic agents. Examples for this are cantharis (as an aphrodisiac), Blatta orientalis, tarantula.