Limnognathia

Limnognathia maerski

Limnognathia maerski is a type of multicellular animals within the flatworm -like. It is the only species in the root of Micrognathozoa (size: with small pines). This strain is only in 2000 newly introduced higher-ranking taxon. Limnognathia maerski are very small, less than half a millimeter long, worm-like animals.

System

The highly complex nature of the jaw formation suggested a membership of five years before the first description of Limnognathia maerski introduced large group Gnathifera. First molecular genetic test results for this relationship hypothesis in 2004 by Giribet et al. presented, but did not provide unequivocal support of the membership of Limnognathia maerski to this group. According Giribet et al. is to accept at least a very independent position for Limnognathia, so it is not about a Verzwergungsform within another group. This independent position would justify the introduction of a new high-level taxon Micrognathozoa for Limnognathia, although the exact relationships remain unclear for the time being.

Features

Limnognathia maerski has a combination of features that make it impossible to integrate the animal into one of the previously known strains within the metazoans.

In addition to the immobile cilia that serve to sense perception, there are different arrangements of eyelashes which serve to locomotion and the approach swirls of food. These sit on the ventral side of the front and sides of the head region as well as on the thorax and the abdomen. The lashes of the anterior region are arranged in a horseshoe -shaped rows. You have the task of swirls food particles in the mouth. Next to the cilia of the mouth and on the ventral side of the body are arranged in a different side. These are usually two rows like a brush in groups across the body axis. Each group comes from a single cell. Such cells are called Ziliophoren and come in the animal kingdom otherwise seen only in the microscopic Wenigborstern from the families Diurodrilidae and Neotenotrocha. The four Ziliophoren are arranged laterally adjacent said mouth opening. The Ziliophoren on the ventral side of the body to form two long rows along the body axis. All eyelashes a cell beat in the same rhythm, so that Limnognathia maerski as with comb-like feet can move forward.

The jaw apparatus consists of 15 by muscles and ligaments connected parts. These individual jaw structures are 4-14 microns in size. They include various mutually moveable and partly provided with teeth mouthparts. The pine formations are known as the rotifer and the Gnathostomulida " trophi ". Although very different from the pine Limnognathia maerski in the construction of the other groups, Ultrastructural with the transmission electron microscopy (TEM ) have shown that they are composed, as in the rotifers and the Gnathostomulida of densely packed rods. This feature would speak as a synapomorphy for a phylogenetic relationship of the three groups and support the compilation to an excess strain Gnathifera.

History of Research

Limnognathia maerski was first discovered on Disko Island in West Greenland in 1994 by a group of students of the University of Copenhagen under the direction of Professor Reinhardt Kristensen in a freshwater spring near the Danish Arctic Station. The group wanted to investigate the marine meiofauna of the island's beaches. For filtering out the marine microorganisms fresh water from the nearby spring was used. Previously, the individuals organisms were determined in order to distinguish them from the marine organisms can. In addition to various rotifers doing some kind was observed, which differed by the type of swimming movement of the rotifers. It soon became clear that the new way with the help of applied on the ventral side cilia could crawl over moss leaflets, This locomotive capability is not known by rotifers. Even under the light microscope at high magnification showed bodies that do not occur in rotifers.

Some specimens of the new species were brought to the laboratory of the Zoological Museum in Copenhagen and examined under the electron microscope. It was found that the jaw apparatus of Limnognatha maerski differs significantly from other groups of animals, and there was a new taxonomic group called Micrognathozoa set up, but so far only includes one type.

The species has now been found on the subantarctic Crozet Islands.