Question

Ambulacral grooves of Asterias are present on
A) Oral surface
B) Aboral
C) Both A and B
D) None of the above

Answer 1

Hint:Asterias is one of the common genuses of starfish which, not being actual fish, have been renamed sea stars. They are exclusively marine, bottom dwelling organisms, often found in the littoral zone along the shore.

Complete answer:
The oral surface is the ventral surface of the Asterias. Other than the mouth, this surface also has ambulacral grooves that extend from the mouth down the tentacles. These grooves contain the many suckers or tube feet of the starfish. One of their functions is to help pass food towards the mouth. Besides this function, the tube feet also have the role of helping the Asterias attach to the substratum. Option A is correct.

The aboral surface is farthest from the mouth. It is the dorsal surface of the sea star. On the aboral surface is found the madreporite, a structure that filters water and supplies it to the vascular system. The aboral surface also has the anus right in the middle of the central disc. Option B is not correct.
As option A is the correct answer, and B is incorrect, Option C is therefore incorrect. For the same reason, option D is also incorrect.

Hence the correct answer is option ‘A’.

Note:Sea stars also have large spines lining the ambulacral grooves. These help in locomotion of the animal along the bottom of the ocean. AS they get closer to the mouth, the sines become softer and are called papillae. The end of each arm also has a simple eye placed at the end of it.