Question

The number of tentacles in Hydra are
A) 6 to 10
B) 10 to 16
C) 16 to 20
D) 20 to 26

Answer 1

Hint: Hydra are freshwater animals belonging to the Phylum Coelenterata. They have a bassel shaped body which has a mouth at the top. The mouth is surrounded by a ring of Tentacles which are extensible and have stinging cells.

Complete answer:
Hydra has a plain, erect tube-like arrangement of the body stalk at the top of which is the mouth . This is surrounded by a ring of tentacles that differ in length depending on the species. These are usually 6-10 in number.

A large number of specialized cells called cnidocytes are found in the tentacles, containing stinging structures known as nematocysts.
The body column and tentacles are extremely extendable due to simple construction. Hydra stretches the tentacles while hunting, moves them slowly around and waits for some suitable prey to come into touch. Neurotoxins released from the stinging nematocysts paralyze small animals that come across the tentacles. Tentacles coil around the struggling prey and pull it into the opening of the swollen mouth. Digestion may begin when the victim is enclosed within the body cavity.

Let us analyze the options to find out the correct option.

Option A: The number of tentacles in Hydra are 6-10. Therefore, this is the correct option.
Option B, C and D: These are incorrect options.

Hence, the correct answer is option (A)

Note: 1.Hydra feeds on nematodes, crustaceans, etc.
2.Tentacles help them to draw their food to the mouth.
3.For long periods, Hydra stays stationary, although it may travel by bending the body, extending the tentacles, releasing the basal disk, and re-attaching it.