It is true.
True. The majority of radially symmetric animals, such as jellyfish and sea anemones, are aquatic, as their body design is well-suited for movement and feeding in water environments.
Most annelids are essentially tubes so they are radially symmetric.
Aquatic animals. most of the time they say aquatic wildlife, very few will say aquatic animals
cnidarians
Aquatic animals
dolphins can not stay in water long time like most aquatic animals
true
They are aquatic.
No
Yes most of them are.
Aquatic or semi-aquatic? I'm pretty sure most mammals can swim, but I wouldn't say that most mammals are aquatic. In fact, I think most animals can swim (excluding a few bugs, etc.)
The respiratory system of most non-aquatic animals is entirely enclosed in the human body and connected with the lungs. Many aquatic animals have developed open respiratory systems that include features like the gills.