Water Vascular System of Sea Star

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Questions and Answers

What is another name for the water vascular system in sea stars?

Gastrovascular system

Amphibious network

Aquatic circulatory system

Ambulacral system (correct)

Which of the following is NOT a function of the water vascular system?

Digestion (correct)

Respiration

Locomotion

Food capturing

Which structure is directly responsible for the entry of water into the water vascular system?

Stone canal

Tube feet

Ring canal

Madreporite (correct)

What type of structure supports the walls of the stone canal?

Calcareous rings Signup and view all the answers

Which of the following structures is believed to have a lymphatic function in the water vascular system?

Tiedemann’s bodies Signup and view all the answers

What shape does the ring canal typically have?

Pentagonal Signup and view all the answers

What do polian vesicles primarily serve as in the water vascular system?

Contractile reservoirs Signup and view all the answers

Which of the following correctly describes the madreporite's location?

On the aboral surface of the central disc Signup and view all the answers

What is the primary function of the lateral canals in the ambulacral system?

To regulate pressure within the ambulacral system. Signup and view all the answers

Which part of the tube foot is responsible for attachment to the substratum?

Sucker Signup and view all the answers

How does an Asterias achieve locomotion on a horizontal surface?

By lifting its arms and extending the tube feet. Signup and view all the answers

What mechanism allows the tube feet to extend when moving?

Influx of water into the ampullae. Signup and view all the answers

In what direction does the radial water canal run within the arm?

Immediately to the oral side of the ambulacral muscles. Signup and view all the answers

What sequential action follows the attachment of the tube feet to the substratum?

The longitudinal muscles of the podia contract. Signup and view all the answers

Which structure acts like a valve in the lateral canals?

Ampulla Signup and view all the answers

What aids in the attachment of the tube feet to surfaces aside from suction?

Mucus secreted by the tips of the tube feet. Signup and view all the answers

Study Notes

Water Vascular System of Sea Star

The water vascular system is a modified part of the coelom.
It's a system of sea water-filled canals with specific corpuscles.
It's also called the ambulacral system.
Functions include locomotion, capturing food, and respiration.

Essential Parts of the Water Vascular System

Madreporite: A rounded calcareous plate on the aboral surface of the central disc. It has radiating grooves and pores. The pores lead into canals that collect water.
Stone canal: Connects the madreporite to the ring canal. It's lined with tall flagellated cells.
Ring canal: A ring located inside the peristomial ring of ossicles, above the hypo-neural ring sinus.
Radial canal: Extend from the ring canal into each arm.
Tiedemann's bodies: Small yellowish, irregular or rounded bodies, inter-radially, from the ring canal, possibly lymphatic glands.
Polian vesicles: Pear-shaped bladders connected to the ring canal, regulating pressure and producing amoeboid cells.
Lateral canals: Short, narrow branches extending from the radial canals, connected to tube feet.
Tube feet: Hollow, elastic, thin-walled structures with an ampulla, a podium, and a sucker. They are the primary means of locomotion, respiration, sensing, and capturing food.

Detailed Descriptions of Key Components

Madreporite (i): Its surface has wavy grooves or furrows containing minute pores, leading to canals uniting to form collecting canals. These canals open to an ampulla.
Stone canal (ii): The ampulla opens into an S-shaped stone canal, descending to the ring canal, and lined with tall flagellated cells. In adult Asterias, it contains ridges with spirally rolled lamellae.
Ring canal (iii): Located inner side of the peristomial ring and above the hypo-neural ring sinus, its shape is pentagonal
Tiedemann's Bodies (iv): Inter-radially located small, yellowish glandular bodies, attached to the peristomial ring ossicles; they are hypothesized to create amoeboid cells for the system.

Additional Components

Polian vesicles (v): Situated within the inter-radial area of the ring canal, little pear-like, thin-walled, and contractile bladders
Radial canals (vi): Extend throughout each arm from the ring canal, terminating at the terminal tentacle, running immediately to the oral side of the ambulacral muscles.
Lateral canals (vii): short branches extending from the radial canals, attached to tube feet. They possess a valve preventing backward water flow. tube feet connected to lateral canals.

Tube Feet (viii)

Tube feet are found in four rows in each ambulacral groove within each arm.
They're thin-walled, closed-cylinder structures with an upper sac-like ampulla, a middle podium, and a lower disc-like sucker.
Their purpose is primarily locomotion, respiration, sensing, and food capture.

Locomotion on a Horizontal Surface

An Asterias moves by contracting the ampullae, forcing water into the podia, extending the tube feet.
Podia attach to the substrate and the muscles contract, moving the animal. This process is repeated for further movement.

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Description

Explore the fascinating water vascular system of sea stars, also known as the ambulacral system. This quiz covers its essential parts, such as the madreporite, stone canal, and radial canals, along with their functions in locomotion and respiration. Test your knowledge on how these components work together for the sea star's survival.