Final answer:
Bryozoans are aquatic invertebrate animals that form colonies and are known as filter feeders. They keep their eggs internal, contributing to the group's survival within their various colony structures. These colonies can be diverse in form and have a significant number of living species and fossil record.
Step-by-step explanation:
Bryozoans, a type of aquatic invertebrate animals, possess a unique reproductive strategy in which they keep their eggs internal. Colonies of bryozoans are typically benthic, sessile, and marine immobile, attaching themselves to substrates in their environment. The individuals within these colonies, known as zooids, are bilaterally symmetric and contribute to the feeding and excretion activities crucial for the colony's survival. Bryozoan colonies are diverse in structure, ranging from gelatinous to branching forms, reminiscent in appearance to corals but differing in their internal structure with the absence of septa or a columella. These hardy organisms have been present since the Ordovician period and play a significant role as filter feeders, with over 6,000 known living species and a rich fossil record indicating a high diversity of species.