Question

Hydra recognizes its prey by
A)Special organs
B)Chemical stimulus of prey
C)Nematocyst
D)Mechanical stimulus of Prey

Answer 1

Hint: Hydra phylum cnidaria. Most of the cnidarians are marine animals except the hydra which lives in freshwater ponds, lakes, and streams. They reproduce by sexual and asexual method, in the tube shape polyp form.

Complete answer:
Nematoblasts and Cnidoblasts produced nematocyst used for capturing and paralyzing the prey. The Nematocyst consists of coiled and hollow thread consists of barbs or spines and also contains poison.
-When there is an appropriate or right stimulation, they take out Nematocyst from the capsules and entangling organisms victim
-There are four types of Nematocyst present in hydra on their tentacles and ectoderm.
1)The first type of Nematocyst is the largest, Consist of barbs on the end, tie up the prey to the tentacles and when it firmly holds the prey, the hydra envelopes an organism and consumes it.
2)The second type of nematocyst is a smaller one consisting of short and thick corkscrew thread that helps in surrounding the prey.
3)The third type of nematocyst is the sticky bean-shaped object. It is present at its and used for locomotion.
4)The four types of nematocysts consist of spines that are running along the thread. This type of nematocyst used to defend hydra against potential predators.

Additional Information: -Hydra found attached to the submerged vegetation or with any solid object. Its body remains extended with the tentacles when it is undisturbed, showing expansion and contraction without any reason.
-Hydra is carnivorous and feeds on small insect larvae and small crustaceans. They are solitary in habit and reproduce sexually as well as asexually

So, the correct answer is,” Nematocyst”.

Note: -The common features of all the cnidarians are Nematocyst or cnidocytes. These are produced from the Golgi apparatus within a specialized cell as a secretory product.
-Nematocysts used for capturing prey and also for defense. It is also used for locomotion.
-Whenever prey makes contact with the tentacles of hydra, it stimulates the Nematocyst which results in a flap of tissue that covers the nematocyst that is the operculum to fly open.