Which feature is characteristic of organisms with a polyp body plan?

The characteristic feature of organisms with a polyp body plan is that they are typically sessile and anchored. Polyps, which are one of the two main body forms found in cnidarians (the other being the medusa), generally attach to a substrate such as a rock or the ocean floor. This sessile lifestyle is key to their feeding strategy; polyps extend their tentacles to capture food particles from the water surrounding them, relying on their anchored position for stability while feeding.

In contrast, free-swimming organisms typically exhibit a medusa body plan, which allows for greater mobility in the water column. Bilateral symmetry is not a feature of polyps; rather, cnidarians generally display radial symmetry, allowing them to interact with their environment equally from multiple directions. Furthermore, polyps, like many invertebrates, have relatively simple nervous systems, which are not as complex as those found in other animal groups that exhibit advanced behaviors and capabilities. Thus, the key characteristic of polyp organisms is their sessile nature, distinctly differentiating them from their more mobile counterparts.