Question

In Hydra, new nematocysts develop from
(А) Cnidocytes
(B) Glandular cells
(С) Germ cells
(D) Interstitial cells

Answer 1

Hint:-Hydra belongs to the kingdom coelenterate of Animalia . The body of coelenterates bear a central gastrovascular cavity which opens to the outside through a single opening called mouth. Mouth is an aperture present on the hypostome. Hydra reproduces mainly by budding in which small outgrowth protrudes from parent hydra.

Complete answer:Characteristics features of hydra includes :-
- Hydra flourishes well in cool, clean and stagnant water.
- Number of tentacles surrounding the mouth in Hydra is 6-10. Tentacles of Hydra are hollow while that of obelia are solid.
- Food of Hydra is water fleas (Daphnia and Cyclops). Thus, it is carnivorous. It cannot digest starch.
- No free larval stage in development of Hydra. Hence, development is direct.
- Most species of Hydra are dioecious/unisexual. Male Hydra bears 1-8 conical testes towards distal end.
Now let us gather information about given options:-
(A) Cnidocytes:- Many of the interstitial cells of the epidermis become specialized to form the stinging cells, called the cnidoblasts. They migrate to the tentacles through the mesoglea by means of amoeboid movements. Projecting cnidoblasts act as organs for offence and defence.
(B) Glandular cells :- The glandular-muscle cells, chiefly in the region of the pedal disc. are especially modified to secrete sticky material for attachment of animals to substratum.
(С) Germ cells :- They remain in restricted regions. They proliferate to form gonads. They are ectodermal in hydrozoa and endodermal in Scyphozoa and Anthozoa
(D) Interstitial cells :- They are totipotent cells which give rise to all the different cells of the body as new cells arise from this thus nematocyst will develop from the interstitial cells.


Our required option is (D) that is Interstitial cells

Note:- Hydra contains some other types of cells also as Sensory cells : They are scattered throughout the epidermis. They are most numerous on the tentacles, hypostome and basal disc. They receive and transmit impulses.
Nerve cells : They occur for the first time in coelenterates. They are present at the base of epitheliomuscular cells. They conduct impulses in all the directions.