Respuesta :

When there is the presence of gills it will be easy to determine if the animal is aquatic or mollusk.

Aquatic means related to water. While Mollusca is termed as the large phylum of invertebrate animals whose members are called mollusks. Most of the mollusks live in water.

The most numerous mollusks are mantle which is important for cavity and is used for excretion and breathing, the presence of radula and their structure of the nervous system.

Answer:

Presence of gills indicate the given mollusc is aquatic.

Explanation:

Respiratory organ separates land molluscs from aquatic ones. Aquatic molluscs have gills as respiratory organs while land molluscs do not have gills. Land snails have vascularized mantle that serve the function of lung. The vascularized lining of the mantle cavity serve as site of gaseous exchange in land molluscs.