Final answer:
The class Anthozoa includes marine invertebrates like corals and sea anemones, known for their polyp-only life stages and absence of a medusa phase. These cnidarians are pivotal to marine biodiversity and exhibit various forms of feeding, including capturing prey and symbiotic relationships.
Step-by-step explanation:
The cnidarian class that includes stony corals, sea anemones, sea fans, sea whips, sea pansies, and sea pens is Anthozoa. meaning they only have a polyp stage in their life cycle and lack a medusa stage.
Sea anemones, sea pens, and corals are all examples of Anthozoa The class Anthozoa is comprised of marine invertebrates that have a sessile polyp body plan, meaning they do not possess a medusa stage in their life cycle.
This class is well known for their vibrant colored sea anemones and the various species of corals. Members of Anthozoa are usually attached to a substrate and can range in size; for example, sea anemones can vary from 1.8 to 10 cm in diameter.
Corals within this class are known to be carnivorous, utilizing their tentacles to catch zooplankton and other small organisms, as well as sometimes hosting symbiotic algae that contribute to their nourishment via photosynthesis. With over 6,100 described species, members of the class Anthozoa are diverse and represent a significant portion of the marine biodiversity found within coral reefs and other oceanic habitats.