Question

what is the usefulness of phylum cnidaria (hydra)

Answer 1

Answer:

Hope it helps you!

Explanation:

About Cnidaria:

➪The name Cnidaria is derived from the cnidoblasts or cnidocytes , which contain the stinging capsules or nematocytes present on the tentacles and the body.

➪Cnidarians exhibit tissue level of organisation and are diploblastic, digestion is extracellular and intracellular, and have a central gastro-vascular cavity with a single opening, hypostome.

➪Cnidarians like corals have a skeleton composed of calcium carbonate and exhibit two basic body forms called polyp and medusa, polyp is sessile and cylindrical form like Hydra, whereas, the latter is umbrella-shaped and free-swimming like Aurelia.

➪Cnidarian which exist in both polyp and medusa forms exhibit alternation of generation called as

Polyps produce medusae asexually and medusae form the polyps sexually (e.g., Obelia).

Examples:

Physalia (Portuguese man-of-war), Adamsia (Sea anemone).

Uses:

Cnidarians are very much important as predators in the open ocean. They help in the smooth functioning and working of the food chain and food web of the ocean ecosystem a lot. Cnidarians like the Coral reefs are considered to be one of the most diverse and valuable ecosystems on earth.

Answer 2

Hydra (/ˈhaɪdrə/ h-EYE-drə) is a genus of small, fresh-water organisms of the phylum Cnidaria and class Hydrozoa. They are native to the temperate and tropical regions.[2][3] Biologists are especially interested in Hydra because of their regenerative ability – they do not appear to die of old age, or indeed to age at all.