Detecting the tapeworm species longer (0.3m)

Canadian researchers have recently discovered a group of tapeworms - flatworms that can grow to over 30 fut parasites in the digestive system of humans, fish and other animals by sucking up nutrients from animals. master.

This newly discovered tapeworm group is named Rhinebothriidea, including parasitic worms on stingrays and even fut. Claire J. Healy, curator of the Ontario Royal Museum in Toronto and her colleagues, proved that this is a new group.

The case of tapeworm infection is quite rare in the United States. People often do not know that they are infected with fluke, possibly through animals or water sources, but symptoms include abdominal pain, nausea, vomiting, loss of appetite and malnutrition. The main treatment is a deworming medicine that has the effect of destroying and getting rid of them.

Above is an electron micrograph of the Rhinebothrium sp.- a kind of Rhinebothriidea tapeworm.The head of the parasite is about 900 µm wide.This flukes, like all rhinebothriidean flukes, have four legs that stick on the flukes, each growing from a stalk.(Photo: Claire J. Healy)

The discovery of this new Rhinebothriidea group, which includes up to five new species to science, represents a significant step forward in understanding the evolutionary correlation of tapeworms. This new group will be published in detail in the March 2009 issue of the International Journal for Parasitology.

Healy said: 'This study clarifies an important backbone of the life tree of the flatworm. It sets the stage for further research on the evolutionary relationship between flatworms'.

Re-study classification

The study begins with a comprehensive survey of a group of parasitic flatworms in the body of stingrays (stingrays and its relatives). Scientists used to classify these worms into the Tetraphyllidea subfamily - a family that has lost its identity over the past two decades, and is now considered a subspecies for species that do not really belong. about a certain category.

To solve this problem, Healy and her colleagues have established the genetic sequence of 58 flatworm species, belonging to 30 species out of 5 genera , most of the gene sequences obtained for the first time from this study. .

Above is an electron micrograph that scans the head (front-clinging organ) of Scalithrium n species. sp. - a type of tapeworm belonging to the new Rhinebothriidea family. The fluke head is about 300 µm wide. (Photo: Claire J. Healy)

Analysis of the data helped establish an evolutionary tree that clearly shows a flatworm species, including the studied species, quite far from Tetraphyllidea.

Using light and scanning electron microscopy techniques, along with histology, the team found that members of the flatworm have natural traits that express a common ancestor. .

Interesting details

Flatworms that use muscle or muscle tissue are called clinges to adhere to the intestinal surface of the host. The senses of members of this new flatworm group are attached to the muscle stalks, not directly attached to the flukes. Based on this morphological characteristics, members of the new group can be classified into the Rhinebothriidea family, separate from the Tetraphyllidea family.

This new family consists of 13 species, including 5 new species, discovered during the study of Healy and colleagues.

More than 200 species, many of which are unnamed, are classified as Tetraphyllidea and more and more species have been discovered according to the research process. Additional studies on Tetraphyllidea and its relatives may explain the mechanism by which these worms can evolve from a lifestyle in saltwater to freshwater and on land.