Mouth:
The mouth is an opening, which lies at the base of the vestibule and is surrounded by a membrane called velum. Numerous slender ciliated tentacles called velar tentacles arise from the free margins of the velum. The velar tentacles act as strainer.
Pharynx:
The mouth leads into a large sac like pharynx whose walls are pierced by many gill slits. Two types of gill bars separate the successive gill slits
Primary gill bar
Secondary gill bar.
Gut or intestine:
The epipharyngeal groove leads to the back end of the pharynx where lies the opening of the short, ciliated esophagus. The esophagus is followed by a wide mid-gut, behind, which is ilio-colonic region that opens into a narrow hindgut. The hindgut terminates at the anus, which is a small opening on the left hand side of the ventral fin.
Hepatic caecum:
The hepatic caecum or mid gut diverticulum is a digestive gland. It arises as a blind sac from the junction of the esophagus and mid gut. It lies on the right hand side of the pharynx, protruding into the arterial cavity. The caecum secretes enzymes, which are carried to the midgut. The cells of its lining phagocytes the smallest food particles and digest them.
The mouth is an opening, which lies at the base of the vestibule and is surrounded by a membrane called velum. Numerous slender ciliated tentacles called velar tentacles arise from the free margins of the velum. The velar tentacles act as strainer.
Pharynx:
The mouth leads into a large sac like pharynx whose walls are pierced by many gill slits. Two types of gill bars separate the successive gill slits
Primary gill bar
Secondary gill bar.
Gut or intestine:
The epipharyngeal groove leads to the back end of the pharynx where lies the opening of the short, ciliated esophagus. The esophagus is followed by a wide mid-gut, behind, which is ilio-colonic region that opens into a narrow hindgut. The hindgut terminates at the anus, which is a small opening on the left hand side of the ventral fin.
Hepatic caecum:
The hepatic caecum or mid gut diverticulum is a digestive gland. It arises as a blind sac from the junction of the esophagus and mid gut. It lies on the right hand side of the pharynx, protruding into the arterial cavity. The caecum secretes enzymes, which are carried to the midgut. The cells of its lining phagocytes the smallest food particles and digest them.
