The characteristic shared by mollusks and arthropods is

The answer is: It has no backbone.

Mollusks and arthropods are both invertebrates, which means they do not have a backbone. This is one of the common characteristics of the two phyla of the animal kingdom. Molluscs and arthropods can also be found in freshwater and saltwater environments, and they reproduce sexually with their male and female counterparts. In terms of development, both molluscs and arthropods go through stages before reaching maturity. These similarities make it easy to see why these two divisions of animals are so closely related.