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Unlike the flatworms, nematodes have a tubular digestive system, with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum. [3]
For example, the word stylet or stomatostyle is used for the primitive piercing mouthparts of some nematodes [1] and some nemerteans. In these groups the stylet is a hardened protrusible opening to the stomach. These stylets are adapted for the piercing of cell walls and usually function by providing the operative organism with access to the ...
Upon passing through the bird's digestive system the eggs are defecated out. The eggs are then picked up by the ants and fed to their larvae. Once inside the immature ant gut the eggs migrate to the gaster where they will fully mature. Once the ant larvae pupate the mature nematodes begin to reproduce inside of the gaster.
Trichinella is the genus of parasitic roundworms of the phylum Nematoda that cause trichinosis (also known as trichinellosis). Members of this genus are often called trichinella or trichina worms. A characteristic of Nematoda is the one-way digestive tract, with a pseudocoelom (body cavity made up of only an ectoderm and endoderm).
The developing digestive tube of an embryo forms as a blind pouch called the archenteron. In protostomes , the coelom forms by a process known as schizocoely . [ 6 ] The archenteron initially forms, and the mesoderm splits into two layers: the first attaches to the body wall or ectoderm , forming the parietal layer and the second surrounds the ...
Ascaris is a nematode genus of parasitic worms known as the "small intestinal roundworms". [1] One species, Ascaris lumbricoides , affects humans and causes the disease ascariasis . Another species, Ascaris suum , typically infects pigs .
The excretory system of F. hepatica contains a network of tubules surrounding one main excretory canal. This canal leads to the excretory pore at the posterior end of the fluke. This main canal branches into four sections within the dorsal and ventral regions of the body. The excretory system functions in excretion and osmoregulation. [20]
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and other animals, including the esophagus , stomach , and intestines .