Question

The diagram below illustrates a medusa. Study the diagram to answer the question that follows:

In which group and its examples this body form is dominant?
A. Hydrozoa : Obelia, Hydra, Physalia
B. Anthozoa : Meandrina, Pennatula, Adamsia
C. Scyphozoa : Aurelia, Jellyfishes
D. Cnidaria : Hydra, Aurelia, Obelia

Answer 1

Hint: In the early 20th century, medusoid scyphozoans were put under the relationship between Scyphozoa and Medusae. The medusoid Scyphozoa belongs to the phylum Cnidaria and contains a jelly-like substance called mesoglea. The mesoglea contains several layers of cells with diverse shapes, which can be seen through transparent bodies.

Complete step-by-step answer:

Their external shape has a smooth semi-transparent bell or umbrella-shaped form, free-swimming in a solitary manner. They are distributed worldwide; most of them live in temperate and tropical regions. Scyphozoa is a class of cnidarian medusoid. Medusae are the most familiar form of scyphozoans. The class Scyphozoa has a few living members, some of which can be found in shallow waters, while others live in deep oceans and seas. Scyphozoans are free-swimming, solitary, and umbrella- or bell-shaped, with a mouth on the outer surface of the umbrella or bell (hence their name). Medusa is a medusoid form. It includes a bell-shaped body and tentacles. The tentacles are more numerous than the bell and have suckers on their tips. The Scyphozoa is a group of mostly free-swimming jellyfish that includes medusoid forms.
Its size ranges from small to large, and its body shape is an umbrella- or bell-shaped, with tentacles that are either free or attached to it via a peduncle (a thin supporting structure). It has a mouth at the end of its bell. Scyphozoa has a free-swimming bell- or umbrella-shaped form that is solitary. Its mouth is located at the center of the oral surface and has tentacles on its oral surface and stomach region. Scyphozoa's body is almost covered by a thin cuticle containing air chambers under the gut lining.

Option C is the right answer.



Note: Scyphozoa is the name given to a group of marine invertebrates with medusoid forms. Scyphozoa includes approximately 230 species, which are classified into several subgroups.