Animal

Animals are after biological understanding of eukaryotic organisms that do not obtain their energy through photosynthesis and use oxygen for respiration, but no fungi. However, for energy and material recovery do animals feed on other organisms ( heterotrophic ). Most animals can move actively and have sensory organs. The science of the animals is zoology.

According to an estimate omitted from the total mass of all living things on earth ( 1.8 x 1015 kg ) about 2 ‰ ( 3.5 × 1012 kg ) to the animals. Systematically play the animals in their entirety today not matter. Most of the group of multicellular animals ( Metazoa ) is meant in the taxonomy with the " animal kingdom ".

Conceptual history and taxonomy

The term animal (Latin: animal) was coined in ancient times and is also the basis established by Carl Linnaeus taxonomy as well as the biological systematics. By the 19th and the beginning of the 20th century only between animals ( Animalia ) and plants (Plantae) was distinguished in introductory textbooks this dichotomy had for long.

Animal Systematics

Relationship

After analysis of their DNA sequences, the animals, the fungi and some essentially unicellular kinship groups form a monophyletic group within the eukaryotes, which is referred to as Opisthokonta. Characteristics of Opisthokonta include: cell with only one flagellum (if not secondary regressed ), this always without mastigonema and with two centrioles. Single-cell types or stages have mitochondria with flat cristae. The Opisthokonta then comprise two sister groups. One of them, Nucletmycea that includes mushrooms and some (usually unicellular ) related groups. The other named Holozoa includes animals and some related groups. These groups are:

  • Ichthyosporea; fungus-like parasites or symbionts, first mainly in fish species now been demonstrated in many other animal groups
  • Filasterea; unicellular protozoa without a cell wall and with very long, unbranched pseudopodia, either free in the sea water live (at Ministerial Vibrans ) or endosymbionts of animals are ( Capsasporidae ).
  • Aphelidea: unicellular parasites of algae with complex life cycle: amoeboid cells penetrate into the pore of the host alga and settle on the cell surface, this set by cell division ( amoeboid or flagellated ) cells spread freely.
  • Corallochytrium limacisporum, a living in the sea ( marine ), free-living protozoa without previously known relative who has only been discovered in 1987 in tropical coral reefs.
  • Collar flagellate ( Choanomonada or Choanoflagellata )

The unicellular forms are in most of these groups by long, unbranched cell processes ( pseudopodia ) marked with rigid internal skeleton made of actin filaments, whereas most other " protists " (eg, the Amoebozoa ) form broad, branched pseudopodia. The filaments may correspond to the cell processes ( microvilli ) of the " collar " of the Kragelgeißeltierchen. The multicellular animals with the most closely related group are the collar flagellate ( Choanoflagellata ), with the Choanozyten the sponges ( Porifera ), a cell type within the vortex chambers, have a lot in common.

The possible relationships of the far unidentified groups studied, and thus the more closely related the animals could therefore look like this:

  • Opisthokonta Nucletmycea
  • Holozoa Ichthyosporea
  • " Filozoa " Filasterea
  • (unnamed) Choanomonada
  • Multicellular animals ( Metazoa )

Like the other mentioned groups would be classified here, is not clear at present, because according to extensive studies are not yet available. Presumably, however, is Corallochytrium limacisporum classify basal to the other groups

Multicellular animals

  • Animalia Choanoflagellata
  • Metazoa Porifera
  • " Eumetazoa Placozoa " Placozoa
  • Eumetazoa Coelenterata
  • Bilateria Acoelomorpha
  • Eubilateria Protostomia
  • Deuterostomia

In the illustrated current system is particularly striking that the Coelenterata be taken into account again. This is done by Philippe et al. (2009) and contradicts, for example, Dunn et al. (2008). In addition, some common group names are different reasons no longer used:

  • Choanoflagellates - Synonym to Choanoflagellata
  • Choanoflagellida - Synonym to Choanoflagellida
  • Choanomonada - Synonym to Choanoflagellata
  • Choanozoa - Paraphylum from Ichthyosporea, Filasterea and Choanoflagellata
  • Coelomata - Synonym for Eubilateria
  • Diploblasta - synonym of Coelenterata
  • Parazoa - Paraphylum from Porifera and Placozoa
  • Radiata - synonym of Coelenterata
  • Triploblasta - synonym of Bilateria
  • Urmetazoa - Synonym to Metazoa

Frequently Animalia is used as a synonym for Metazoa. The one-to wenigzelligen Choanoflagellata are therefore not considered to be real animals, but as a sister group to the Animalia / Metazoa. The monophyletic group that summarizes Choanoflagellata and Metazoa, then has no name.

Legal status ( Germany )

After the traditional Roman legal non-human animals were considered things. This was changed in 1990 with the insertion of § 90a in the Civil Code:

"Animals are not objects. They are protected by special laws. On it applicable to classified information are applied accordingly, unless otherwise specified. "

Biology Mesomycetozoea Trichoplax Deuterostome Digital Object Identifier Current Biology PubMed Central Molecular Biology and Evolution
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