• Asterias is commonly known as star fish or sea star.

• The body is star shaped, consisting of a central disc with five radiating arms which are broad at their base and tapering towards their extremities.

• Body surfaces are distinguishable into an oral surface directed downwards and an aboral surface directed up wards.

• Mouth is pentagonal and lies in the centre of the disc on oral surface.

• Five narrow ambulacral grooves arise from the five corners of the mouth and extend along the middle of the oral surface of five arms up to their margin.