Digestive System of Herdmania 

Herdmania have well develope alimentary canal and digestive glands. The foot of animal consists of microscopic organism. The branchial aperture act as mouth which open into small narrow and tubular buccal cavity the aperture is autrangular the buccal cavity also act as siphon. This buccal cavity open into large pharynx which have several Gill's Slits. It is also help in respiration and fliter organ of foot. The pharynx units with short tubular oesophagus and in the last open into stomach and intestine. The digestive glands are specialy liver and pyloric gland.

The alimentary canal has following organs or structure.

Mouth

The branchail aperture act as mouth of the Herdmania. This aperture is guarded by four sided lips which is provided by muscle it open into tubular siphon. This siphon become wide from anterior where modified into tentraculated ridge. The tentacles are 60-65 in number each tentacles branched into primary, secondary and tertiary. These tentacles act as fine strainer the largest tentacles 8 or 10 in number and 5mm in length in size. The small tentacles are act 2.5 mm in length in size. The small tentacles are act 2.5mm in length and other tentacles are 14-16 in number and 1.5 mm in length. The smallest tentacles are 32 in number and 0.5 mm in length the ratio of tentacles are 1:1:2:4 each tentacles has hair like sensory structure and also nerve fibres and small blood vessel found.

Pharynx

Below the tentacullar ridge has narrow and smooth pharyngeal area. It consists of peribronchial zone which is surrounded by ciliated peripharyngeal groove, the anterior bend is complete and ring like but posterior bend communicate with dorsal lamina and endostyle. The bends are lined with ciliated cells. The siphon open into large spacious thin walled and perforated branchial sac which covers maximum space of atrial cavity. The sac is covered towards the oesophagus the inner wall of branchial sac has about 20 longitude folds. The folds are divided into mid dorsal and mid ventral line the branchail sac is perforated with about 40 lack fine ciliated stigmata.

Endostyle

The endostyle is ciliated groove situated in mid ventral part of branchial sac it is surrounded by endostyler lip. It has two peri-pharyngeal band at anterior side but in posterior side it unite with oesophageal area this area is guarded by two posterior fold the total length of endodtyle is about 8cm the whole length has four rows of glandular epithelium in which two on middle side with long breshy cillia. The endostyler groove secreted large amount of mucous through whole life this endostyler is homologous gland of higher vertebrate.

Dorsal Lamina

The mid dorsal part of pharyngeal body there is long axis row of 20-30 leaf like coiled tentacullar structure dorsal lamina. The dorsal lamina is about 1/6 of total length of endodtyle these are elongated tentacullar then and covered with cillia the broad end is attached but pointed end is free it has connective tissue with nerve fibres and blood sinus.

Oesophagus

The branchail sac open into oesophagus. It has two broad lip like Structure which open into oesophageal pore. The right lil is wider than left. The left lip is narrow but the right lil is wide the oesophagus runs dorsal but bend posterior side it is deep brown in colour and cillia are present in groove.

Stomach

The stomach is about 2-5 cm in length it's wall is thin but lumen is wide the stomach is surrounded by two lobes of liver. On the upper side it has pyloric gland. The anterior side has several opening the opening are situated in small slit. The gastric wall has epithelial cell and cytoplasm is grannular.

Intestine

The stomach leads into 'U' shaped intestine. The proximal part is attached with branched sac. Between two part of intestine there is gonads.

Rectum

The posterior most part of alimentary canal is rectum which open into dorsal chamber and finally into anus the anus is guarded by four lips and this anus finally open into atrial chamber.

Digestive gland 

There are two digestive gland are found in Herdmania.

1. Liver
2. Pyloric gland

Liver 

The liver is by lobed which surrounded the stomach. The left lobe is divided into five or more small lobes. The right lobe small and ovoidal. It open into stomach by 11 opening. 

Pyloric gland

The next digestive gland is pyloric gland this gland is situated in the wall of lower part of stomach. The pyloric gland  have several branches and developes. It open into intestine. It act as excretory in function and secreates juice in pancreatic nature.

Mechanism of digestion

Herdmania is cilliary or filter feeder. The foods for animal are consist of algae, dtatoms etc. When the water current enter inside the body through mouth and buccal cavity into pharynx and finally into atrial cavity and out through atrial siphon. The branchial tentacles act as sieve or strain which present from large particle only allow minute food particle into the pharynx. The tentacles also act as chaemoreceptor. The large particle thrown out from the body by reverse current.

In stomach the food is digested by enzyme present in liver secretion. Amylase help to hydrolyzed starch into maltose, protease breaks down protein and lypase or fats digested food observe in intestine and undigested food passout from body through atrial aperture.