Balanoglossus is a worm like Protochordate organism. It belongs to

Phylum: Chordata

Subphylum: Hemichordata

Order: Enteropneusta.

Habit and Habitat: It lives in burrows in the sand of intertidal regions of sea water. It lives in 'IT shaped tubes. These tubes will open on both ends.

Shape : It resembles earthworm. Its body is long worm like, it is cylindrical. This animal is called Acorn Worm. It is called tongue worm.

Size : It is 3 cm. to 2 meter in length. Balanoglossus gigas will grow to 2 meters in length.

Colour: Different species of this genus will show different colours. They may be light brown or yellow or light red in colour.

Smell : They give strong smell resembling idoform smell.

Divisions of the Body : The body is bng and is divided into 3 parts.

1. Proboscis

2. Collar

3. Trunk

Proboscis: It is club shaped structure. It is at the anterior end of the body. Its body wall is muscular. It encloses a coelomic cavity called proboscis coebme. In this proboscis stomochord, Heart, pericardium and glomerulus are present.

The posterior end of proboscis is called neck. It connects proboscis with collar. Below this neck a pre-oral ciliated structure is present. It will test the water and food that enters into the mouth.


Collar : It is the middle part. It is a short part. In between collar and proboscis ventrally a big mouth is present. It is permanent opening. Collar contains two coelomic cavities.

Trunk : It is an elongated, posterior part-The body wall is folded hence it gives wrinkled appearance to the body. This trunk is divided into 3 parts.

a) Branchio-genital region

b) Hepatic region

c) Candal region

a) Branchio genital region : This is the first part of the trunk. It includes gills and gonads hence it is called branchio-genital region.

b) Hepatic region: In this part hepatic caecae are seen hence it is called Hepatic region.

c) Candal region : This is the posterior part of the body. At its tip anus is present.

The body of this animal is covered by ciliated epidermis.

This animal will make burrows in the sand with the help of proboscis and collar.