The locomotory organs of Hydra are

(a) Tentacles

(b) Tentacles and basal disc

(c) Hypostome

(d) None of the above

The Hydra attaches itself to a substratum using its basal disc and usually remains upright, though it moves while hunting. Hydra employs several methods of locomotion:

• Walking or looping: It bends down, attaches its tentacles to the ground with the help of glutinant nematocysts, releases the basal disc, shifts it to a new location, and then straightens up. In this way, it can move several inches in a day.
• Inverted walking: It can move upside down by using its tentacles like legs.
• Gliding: The basal disc drags along the surface. Its cells can extend pseudopodia-like structures, similar to Amoeba.
• Floating: Ectodermal cells of the basal disc secrete gas bubbles. These provide buoyancy, allowing Hydra to float on the water surface and drift with currents or wind.

Correct answer: Tentacles and basal disc