While collecting specimens, a marine biologist finds a sessile cnidarian. the medusas that bud from it swim by contracting a ring of muscle in their bells. to which class does this specimen belong?
class hydrozoa
class cubozoa
class scyphozoa
class anthozoa

Class Scyphozoa

Explanation:

In the Scyphozoa class, the predominant and sexual forms are beautiful medusas of varying colors, the true "medusas" often seen on our shores. The polyps are small and correspond to the asexual, short lasting phase. Since this class has the predominant species, the jellyfish, we can conclude that the class that the question is referring to is Scyphozoa.

The medusas are shaped like an umbrella and are different from the group of hydrozoans. They can reach from 2 to 40 cm in diameter. The giant of the group is a North Atlantic jellyfish that reaches 2 meters in diameter.