Question

Biradial Symmetry And Lack Of Cnidoblasts Are The Characteristics Of

• A. Ctenolana and Beroe
• B. Hydra and starfish
• C. Ctenophora and Beroe
• D. Aurelia and Paramecium

Answer 1

Answer: (A), (C)

Ctenophora and Beroe

The correct options are A:

Explanation of correct option-

Phylum Ctenophora

1. Biradial symmetry is a combination of radial and bilateral symmetry.
2. Ctenophores are exclusively marine, radially symmetrical, diploblastic organisms.
3. Cnidoblasts are the oval-shaped cells present on the tentacles and the body.
4. Cnidoblasts are the characteristics of the phylum Cnidaria.
5. Ctenophores show bioluminescence, the property of living organisms to emit light.
6. Beroe is also known as melon jellyfish and belong to the phylum Ctenophora.
7. Ctenolana is also an example of Phylum Ctenophora.
8. Therefore they have biradial symmetry but lack cnidoblasts.

Explanation of incorrect option-

Option B- Hydra and starfish

1. Hydra belongs to phylum Coelenterata.
2. It bears Cnidoblasts which contains nematocysts containing poisonous fluid called hypnotoxin.
3. They are aquatic, mostly marine, sessile or free-swimming radially symmetrical animals.
4. Starfish belongs to the phylum Echinodermata.
5. Echinodermata have an endoskeleton of calcareous ossicles and thus the name is Echinodermata.
6. The adult echinoderms are radially symmetrical.
7. It has water vascular system which helps in locomotion, capture and transport of food and respiration.
8. Example- Asterias (starfish)

Option D- Aurelia and Paramecium

1. Aurelia are coelenterates which bear cnidoblasts.
2. Paramecium belongs to phylum Ciliophora.

Final answer: Biradial Symmetry And Lack Of Cnidoblasts Are The Characteristics Of Ctenolana and Beroe and Ctenophora.