Question

Nutritionally, Hydra is
A. Saprophytic
B. Insectivorous
C. Herbivorous
D. Carnivorous

Answer 1

Hint: Hydra is an aquatic animal of phylum Cnidaria and they have a number of tentacles around their mouth. The body of hydra is simple, thin, tubular and they are mostly found in freshwater.

Complete Answer:
Let’s analyse the options one by one.
- Option A: Saprophytes are organisms that can’t make their own food and they feed on dead and decaying organic matter. Some fungi like mushrooms and yeasts are examples of this. Hydra are not saprophytes. Therefore this is an incorrect option.
- Option B: Insectivorous are animals or plants which are adapted to feed on insects. For example, a spider is an insectivorous animal and pitcher plant is an insectivorous plant. Therefore this is an incorrect option.
- Option C: Herbivorous are animals which feed on plants and plant products. Deer, pandas etc. are some examples of herbivores. Therefore this is an incorrect option.
- Option D: Carnivorous are animals that prey on other animals for nutrition. They will have adaptive structures to capture prey.
Hydra lives in aquatic habitat and feeds on aquatic invertebrates. They capture the prey using their tentacles and move them into mouth aperture. Hydra is carnivorous. Therefore this is a correct option. Lions, leopards, sharks etc are other examples of carnivorous animals.

Thus the correct option is D: carnivorous.

Additional information: Hydra are known to be biologically immortal because they don't undergo senescence and have high regeneration capacity.

Note: Omnivorous animals are those which feed on both other animals and plants. Humans are under this category. Hydra is strictly carnivorous. Hydra possess stinging cells called nematocysts on their tentacles. The tentacles tangle up the prey and stinging cells release toxins that paralyse the prey.