Question

Corals are

• A. Poriferans attached to some solid support
• B. Cnidarians, that are solitary living
• C. Poriferans present at the seabed
• D. Cnidarians that live in colonies

Answer 1

The correct option is D

Cnidarians that live in colonies

The correct option is D

The explanation for the correct option

1. Cnidaria is a phylum under the kingdom Animalia
2. The name cnidaria is derived from the cnidocytes (which contain the stinging capsules or nematocysts) present on the tentacles and the body.
3. Cnidarians show two basic forms called polyp and medusa.
4. Polyps form medusae asexually and medusae form the polyps sexually.
5. Some cnidarians live independently, while others live in colonies
6. Coral reefs are composed of colonies of coral polyps.
7. Corals have a skeleton formed of calcium carbonate.

Explanations for the incorrect option

Option A

1. Poriferans is a phylum under the kingdom Animalia
2. They are also called sponges.
3. The body is supported by a skeleton made up of spicules or spongin fiber
4. The phylum of Porifera contains sessile organisms, most of which live in marine habitats.
5. They spend their life attached to a substratum through a holdfast.
6. So these are incorrect with respect to corals which belong to the phylum Cnidaria

Option C

1. Poriferans generally include porous animals called sponges.
2. They can not move and generally remain attached to the surface by holdfast
3. They have water transport and a canal system
4. The Canal system helps them achieve excretion and respiration and reproduction.
5. Examples are Sycon and Euspongia.

Option D

1. Cnidarians are generally marine
2. Some cnidaria is solitary living
3. An example of solitary living is Jellyfish

Final answer: Corals belong to the phylum Cnidarians that live in colonies.