Question

Hydra is
A. Triploblastic, radial symmetry and acoelomate
B. Triploblastic, radial symmetry and automate
C. Diploblastic, radial symmetry and acoelomate
D. Diploblastic, radial symmetry and automate

Answer 1

Hint: Hydra is a Cnidaria that is mainly aquatic and are distributed widely in the freshwater. There are two layers of tissues in the body of these organisms. Their body is generally the same when comparing the left side of them with the right side.

Complete answer:
Hydra is an aquatic animal belonging to phylum Cnidaria and class hydrozoa that are native to temperate and tropical regions. They are tubular, radially symmetrical with their mouth surrounded by tentacles present at the distal end and petal disc at the proximal end.

STRUCTURE- Hydra has a tubular body up to 10 mm long when extended and secured by a simple adhesive foot known as a basal disc. They are generally triploblastic and acoelomate. They take up oxygen from the water that enters the cavity and get the wastes out like carbon dioxide from this cavity only. The cells that line up this cavity helps in taking up the nutrients for the body.

MORPHOLOGY - They generally have two main body layers because of which makes them diploblastic. It has an outer layer called the epidermis and the inner layer called as gastrodermis as it lines the stomach. The cells that are present in them are simple. They respire and excrete through diffusion that takes place through the surface of the epidermis whereas larger excreta are discharged through the mouth.

NERVOUS SYSTEM- It is a nerve net that is structurally simple as compared to more derived animals. They do not contain recognizable brains or muscles. These nerves connect sensory photoreceptors and touch-sensitive nerve cells that are located in the body wall and on the tentacles.

LOCOMOTION- Hydra are generally sedentary but they occasionally move especially while hunting. They move through looping and somersaulting. They usually move by bending over and attacking themselves to the substrate with the mouth and tentacles and relocate their foot which helps them in looping. While somersaulting, they bend their body over and make a new place of attachment with the foot. They also move by the amoeboid motion of their bases or by detaching from the substrate and floating away in the current.

So, the correct answer is option C, Diploblastic, radial symmetry and acoelomate.

Note: All the hydra species feed on other small invertebrate animals like crustaceans. They are composed of two layers of cells separated by a thin, structureless layer of connective tissue called mesoglea and the enteron, a cavity containing intestinal organs.