Ceriantharia

Ceriantharia is an order of marine animals belonging to the class Anthozoa, which also includes corals and sea anemones. However, ceriantharians are distinct from these more familiar cnidarians. They are commonly known as "tube-dwelling anemones" or "poverty corals" due to their appearance and habitat.

These solitary polyps are characterized by their ability to secrete a secreted tube made of mucus and undischarged nematocysts, which they inhabit. This tube can extend deep into the sediment or be attached to a hard substrate. The main body of the ceriantharian, the column, lives within this protective tube, with only the oral disc and tentacles extending into the water column.

Ceriantharians possess two distinct sets of tentacles. The first, marginal tentacles, surround the oral disc and are used for feeding, capturing small planktonic organisms. The second set, oral tentacles, are located closer to the mouth and are thought to play a role in manipulating food or in defense. Their coloration can vary widely, from dull browns and grays to vibrant blues and purples, often with striped or patterned tentacles.

They are found in marine environments worldwide, from shallow coastal waters to the deep sea. Ceriantharians are suspension feeders, passively capturing food particles that drift by. Their presence is often an indicator of a healthy marine ecosystem. Reproduction can be sexual, with the release of gametes into the water, or asexual through budding.