Water Vascular System of Starfish
Introduction :-
The water vascular system is a modified part of coelom & consists of a system of sea water filled
canals having certain corpuscles. It plays most vital role in the locomotion of the animals &
comprises madreporite stone canal, ring canal, radial canal, Tiedman's body, lateral canals &
tube feet.
(1) Madriporite :-
The madreporite is a rounded calcareous plate occurring on the aboral surface of the central disc
in inter-radial position. Its surface bears a number of radiating, narrow, straight or wavy grooves
or furrows. Each furrow contains many minute pores at its bottom. Each pore leads into a very
short, fine, tubular pore-canal. Which passes inward in the substance of the madreporite. There
may be about 200 pores and pore-canal. The pore-canals unite to form the collecting canals.
Which open into an ampulla beneath the madreporite.
Fig : Water vascular system of Starfish
(2) Stone Canal :-
The ampulla opens into a "S" shaped stone canal. The stone canal extends downwards (orally)
and opens into a ring canal, around the mouth. The walls of stone canal are supported by a series
of calcareous ringd. The lumen of stone canal is lined by very tall flagellated cells. in embryonic
