Question

Polyp phase is absent in:

• A. Hydra
• B. Aurelia
• C. Obelia
• D. Physalia

Answer 1

The correct option is B

Aurelia

The correct option is B

Explanation for Correct answer:

1. Phylum Cnidaria is aquatic creatures that are prevalent in marine waters.
2. They are non-motile or freely floating invertebrates.
3. All animals in this phylum contain unique cells called cnidoblasts/nematocysts.
4. Those with cnidoblasts can sting other creatures.
5. Toxins secreted by these cells can paralyze prey or an attacker.
6. This phylum's species have two forms: polyps and medusas.
7. The polyp form appears to be more tubular, with tentacles and a mouth at one end.
8. Polyps and medusas both have two tissue layers: ectoderm and endoderm.
9. Diverse creatures abound in the coral reef undersea habitat.
10. Pollution and global warming endanger this habitat.
11. Almost half of the coral reefs are gone, and restoring this ecology is critical.

Explanation for incorrect answer:

Option A

1. Mesoglea, a jelly-like substance, is found in the midst of two strata.
2. Both kinds have a cavity called a coelenteron where digesting takes place.

Option C

1. Polyps contain both reproductive and budding tissues.
2. Polyps are non-motile types of bacteria.
3. Polyps often reproduce asexually through budding.
4. It can, however, transform into a medusa.

Option D

1. Corals are non-motile polyps of the invertebrate phylum Cnidaria.
2. They are economically and environmentally significant.

Final answer:

The polyp phase is absent in Aurelia.