In this post, we will focus on the digestive system of Herdmania, part of the digestive system, alimentary canal and digestive glands in the digestive system of Herdmania, feeding mechanism of Herdmania.
Table of Contents
Alimentary Canal of Herdmania:
The digestive tract in Herdmania is complete, starting at the mouth opening and ending at the anus opening and it is coiled. In the alimentary canal, mouth lead to the buccal cavity, then it leads to the pharynx, esophagus, stomach, intestine, rectum, and finally, open into the cloaca.
Mouth Opening:
At the anterior end of the body branchial siphon open outside through branchial aperture or mouth and the opening is protected by four lips or lobe of the tunic.
Buccal Cavity:
The cavity inside the branchial siphon is covered by the epidermis is known as the buccal cavity or stomodaeum and it is laterally compressed. At the base of the opening of the branchial siphon strong circular muscle fibers, branchial sphincters are present which control the opening of the branchial siphon.
At the base of the branchial siphon, around 64 branchial tentacles are present which are very sensitive. Each branchial tentacles are sickle-shaped and they have paired branch tentacles or tentacles each tentacle is branched further.
The tentacles present at the base of the branchial siphon form a filter for the food entering into the buccal cavity through the branchial aperture.
Pharynx:
The branchial siphon leads to the pharynx, a significant amount of portion is occupied by the pharynx and the pharynx has two different regions, prebranchial zone and branchial sac.
Prebranchial Zone:
It is the anterior part of the pharynx in which region there are no gill slits, folds, or cilia but at the junction of prebranchial zone and branchial sac two circular ridges are present. The circular ciliated ridge, peripharyngeal ridge which encircles a narrow peripharyngeal groove, cilia present on the groove are much smaller than the cilia present on the ridge.
Branchial Sac:
The Prebranchial zone opens into the more wide posterior portion of the pharynx known as the branchial sac, it is also known as pharyngeal basket due to its special appearance on the lateral wall. The pharyngeal sac has several gill slits arranged in transverse rows, the gill slits present on the wall of the pharyngeal sac make the pharyngeal cavity able to communicate with the atrial cavity present outside the pharynx.
In the pharyngeal wall, several longitudinal and transverse folds are present at regular intervals which makes a square and rectangular area on the wall of the pharyngeal wall, known as stigmatic areas. In each stigmatic area some stigmata present, epithelium of stigmata have cilia known as lateral cilia.
The wall of the pharyngeal sac is highly vascularized and adjacent stigmata are separated from each other by the intersegmental bar and vessels.
Trabeculae: In the inner wall of the branchial sac a large number of longitudinal folds are present which increases the surface area of the branchial sac multiple times and they have no cilia. On the outer wall, a hollow strand-like structure is present on the pharyngeal wall is known as trabeculae and each trabecula has blood vessels.
Dorsal Lamina: From the dorsal wall of the branchial sac a flap-like structure is present in a suspended state know as dorsal lamina or hypopharyngeal band.
Endostyle: On the ventral floor of the branchial sac have a longitudinal shallow grove known as endostyle.
Oesophageal Area: On the posterior end the branchial sac opens into the esophagus, esophagus is guarded by two semicircular lip-like a flap.
Esophagus:
The posterior region of the branchial sac opens into a short curved tube, the esophagus which has four ciliated groves.
Stomach:
The esophagus opens into the wider stomach which is guarded by two sphincters at both ends and the stomach has a thin wall. On both sides of the stomach, the liver is present, the right lobe, and the left lobe on two sides of the stomach.
Intestine:
Intestine present in loop state in Herdmania, intestine have a proximal limb, descending limb, distal limb and ascending limb.
Rectum:
The rectum is ciliated internally and shorts which open outside through the cloaca and finally opens into the anus bounded by four lips.
Cloaca:
The cloaca opens outside through the atrial siphon and finally opens outside through the atrial pore.
Reference Habitat and Habits of Herdmania
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Habitat and Habits of Herdmania
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