What is the pharynx of planaria?
The planarian pharynx is a cylindrical muscular organ in the pharyngeal cavity roughly in the center of the body (Figs. 1a, 1b). The inner pharynx cavity opens to the outside with a mouth on the abdominal side. The pharyngeal cavity goes to the digestive cavity further branching in the planarian body.
What is the function of the pharynx in planaria?
The pharynx connects the mouth to the gastrovascular cavity. This structure branches throughout the body allowing nutrients from food to reach all extremities. Planaria eat living or dead small animals that they suck up with their muscular mouths.
Does Dugesia have circular muscles?
(1997). Accord- ing to their description, the body-wall muscles of Girardia (D) tigrina are composed of four layers from outside to inside: an outer layer of circular muscle fibers, a thin layer of longi- tudinal muscle fibers, a layer of diagonal muscle fibers and an inner layer of longitudinal muscle fibers.
Where is Dugesia found?
These common flatworms are found in freshwater habitats of Africa, Europe, Middle East, Asia, and Australia. Dugesia is best known to non-specialists because of its regeneration capacities. Dugesia is the type genus of the family Dugesiidae.
Is planaria harmful to humans?
Land Planarians are reported to be cannibalistic when food resources are low. While they pose no danger to humans or plants, Land Planarians have been labeled a nuisance in the southern United States in particular, and have been known to decimate earthworm populations in farms and earthworm rearing beds.
Why do planaria avoid light?
Planarians are interesting to study for a variety of reasons. First, planarians have bilateral symmetry with two nerves extending the length of the body, an enlarged “brain” (ganglion cell), and two eye spots. The eye spots are sensitive to light. Planarians move away from the light and are most active in the dark.
Which side of the body are the mouth and pharynx of a planarian located?
Planaria (Genus Dugesia) lives in fresh water ponds and is a carnivore. The pharynx can be protruded from the mouth which is in the middle of the ventral side of the animal.
Are planarians parasites?
The majority of members of the phylum Platyhelminthes (the flatworms—a phylum that includes the notorious tapeworms and flukes) are parasitic; planarians are labeled the only free-living (non-parasitic) flatworms in the bunch.
Is a flatworm a parasite?
Flatworm, also called platyhelminth, any of the phylum Platyhelminthes, a group of soft-bodied, usually much flattened invertebrates. A number of flatworm species are free-living, but about 80 percent of all flatworms are parasitic—i.e., living on or in another organism and securing nourishment from it.
Are Planaria and Dugesia same?
Free-living flatworms like the planaria are grouped into the Class Turbellaria. The most common species studied in the lab is the brown planaria, Dugesia. The animal has an acoelomate body (no internal cavity to hold organs), no anus and lacks a circulatory system.
Are Planarians parasites?
What disease does Planaria cause?
Schistosomiasis: A Disease of Flatworm Reproduction Furthermore, both planarians and schistosomes are bizarre (even by flatworm standards!) in that they produce ectolecithal eggs—in which specialized yolk cells surround the fertilized egg before being packed into the eggshell.