Describe the digestive system of Balanoglossus.

The digestive system is complete and straight, beginning at the mouth and ending at the anus. It includes the mouth, buccal cavity, pharynx (with branchial and digestive regions), oesophagus, hepatic caeca, intestine, and anus.

What is the role of cilia in the feeding process of Balanoglossus?

Cilia generate water currents that help in transporting food particles trapped in mucus into the mouth for digestion.

Explain the function of hepatic caeca.

Hepatic caeca are paired outgrowths in the trunk that secrete digestive enzymes and aid in the absorption of nutrients.

What is the location and function of the mouth in Balanoglossus?

The mouth is ventral, located between the collar and proboscis. It leads to the buccal cavity and allows food intake.

How does the pharynx help in digestion and respiration?

The pharynx is divided into a dorsal branchial region with gill slits (respiration/filter feeding) and a ventral digestive region (conducts food).

What enzymes are involved in the digestion process in Balanoglossus?

Amylase from the proboscis slime, and other enzymes from the oesophagus and hepatic caeca help in digestion.

How is undigested food eliminated in Balanoglossus?

Undigested food is passed through the intestine and expelled via the terminal anus.

Explain the feeding mechanism in Balanoglossus.

It uses cilia to draw in water with food particles, which are trapped by mucus and moved to the digestive tract for processing.

Name the different parts of the digestive tract in Balanoglossus.

Mouth → Buccal cavity → Pharynx → Oesophagus → Hepatic caeca → Intestine → Anus

Describe the structure and function of the pharynx in Balanoglossus.

The pharynx has dorsal gill slits for filter feeding and a ventral part that leads food to the oesophagus.

Why is Balanoglossus called a filter feeder?

It filters food particles from water using cilia and gill slits, making it a ciliary filter feeder.

What is the role of mucus in the digestive process of Balanoglossus?

Ans. Mucus traps food particles, making it easier for the cilia to move the food to the buccal cavity for digestion.

Compare the function of the proboscis and collar in feeding.

The proboscis collects food using mucus and cilia; the collar helps guide food to the mouth and aids in burrowing.

How is the intestine of Balanoglossus adapted for digestion?

It is long and coiled with regions like hepatic caeca for enzyme secretion and a large surface area for absorption.

What type of digestion occurs in Balanoglossus?

Extracellular digestion takes place in the digestive tract with the help of enzymes secreted by various parts.

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Digestive System of Balanoglossus

Digestive System Of Balanoglossus

Balanoglossus is a marine, worm-like organism belonging to the phylum Hemichordata. It is commonly known as an acorn worm and is considered an evolutionary link between invertebrates and chordates due to its possession of some primitive chordate characteristics. Balanoglossus is a burrowing animal found in shallow coastal waters, inhabiting U-shaped burrows in sandy or muddy substrates.

1.0Classification

Kingdom: Animalia
Phylum: Hemichordata
Class: Enteropneusta
Order: Enteropneusta incertae sedis
Genus: Balanoglossus

2.0Habit and Habitat

It is marine and cosmopolitan.
It is tubicolous, living in U-shaped burrows excavated in the sandy bottom.

3.0External Morphology

The body of Balanoglossus is soft, elongated, and cylindrical, with a rich ciliation across its surface and a mucus coating.
Its length ranges from 2 cm to 2.5 meters,

4.0Body Division

1. Proboscis or Protostome
2. Collar or Mesosome
3. Trunk or Metastome

1. Proboscis:-

Anterior, muscular, and ciliated
Helps in food collection and burrowing
Contains a proboscis coelom that opens via a proboscis pore

2. Collar:-

Short, cylindrical region behind the proboscis
Contains the mouth on its ventral side
Assists in locomotion and burrowing

3. Trunk:-

Longest part of the body

Divided into three regions:

Branchiogenital region: with gill slits and genital folds
Hepatic region: with hepatic caeca
Post-hepatic region: ends in a terminal anus

5.0Digestive System

The digestive system of Balanoglossus is straight, complete, and functionally specialized for filter feeding.

1. Mouth

Located ventrally between the collar and proboscis

Always open, leads to the buccal cavity

2. Buccal Cavity

Found within the collar region

Lined with cilia that transport food toward the pharynx

3. Pharynx

Located in the anterior trunk

Divided into:
Dorsal branchial portion: Contains multiple gill slits (filter feeding)
Ventral digestive portion: Forms the oesophagus

4. Oesophagus

A narrow continuation from the pharynx to the intestine

Conducts food posteriorly

5. Hepatic Caeca

Paired, sac-like outgrowths in the hepatic region of the trunk

Secret digestive enzymes

Aid in digestion and absorption

6. Intestine and Anus

Intestine runs posteriorly and ends in the terminal anus

Site of digestion and absorption
Waste is expelled through the anus

6.0Feeding Mechanism

Balanoglossus is a ciliary feeder:

Cilia on the proboscis and gill slits create a water current
Food particles stick to the mucus secreted by the proboscis
The food-mucus mass is moved backward to the collar and then enters the buccal cavity
Amylase and other digestive enzymes begin digestion
Further digestion and absorption take place in the hepatic caeca and intestine

Mode of Digestion

Digestion is extracellular, aided by enzymes like amylase
Enzymes are secreted by proboscis, oesophagus, and hepatic caeca
Absorption occurs in the intestinal wall
Undigested waste is eliminated through the anus

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