What is characteristic of all members of the group Lophotrochozoa?

Members of the group Lophotrochozoa are characterized by undergoing a specific type of larval stage known as the trochophore larva. This is a distinct developmental stage that many Lophotrochozoan animals, such as mollusks and annelids, go through. The trochophore larva is typically free-swimming and has a band of cilia around its body, which aids in locomotion and feeding. This feature links these organisms together within the larger classification of Lophotrochozoa, showcasing a shared evolutionary trait.

While there are certainly members of this group that are mobile and some that require aquatic environments, these characteristics are not universally applicable to all Lophotrochozoans. Additionally, not all members of this group have exoskeletons; rather, some have soft bodies and rely on other forms of support and protection. Thus, the trochophore larval stage is the defining and unifying characteristic of all Lophotrochozoan members.