The tube anemone is a large species widespread across the Mediterranean, around the coast of Africa and around Papua New Guinea. The species is known by many names, all of them referring to one aspect or another of the animal’s appearance or behavior – it is often called the tube-dwelling anemone, the colored tube anemone or the burrowing anemone. The creature is not a true anemone in fact, having numerous features that distinguish it from true anemones.
These creatures come in all the colors of the rainbow, usually in combinations of fluorescent colors. They are also quite large, reaching over 20 cm in diameter, with two different sets of tentacles (one of the features that sets tis creature apart from true anemones that have only one type of tentacles) – shorter labial tentacles used for the manipulation of the prey in the center of the disc and longer feeding tentacles used for capturing prey towards the edges around 30 cm in length. The two types of tentacles are usually of different colors. The lower part of the tube anemone consists of a soft, cylindrical body that end in a strong and pointed foot that is used by the anemone to burrow into the substrate (unlike true anemones, these creatures do not attach themselves to the substrate). The body is surrounded by a protective tube built by releasing special, venomous threads that connect to form hard and resistant woven tissue. When the anemone feels threatened, it can either use its venomous tentacles to sting the attacker or it can withdraw into the tube completely and it can also dig a hole in the sandy substrate with its foot and disappear in it.
Tube anemones are nocturnal and carnivorous. Unlike true anemones, these tube-dwelling creatures do not rely on photosynthesis byproducts as sources of energy, obtaining nutrients exclusively from the prey such as small shrimps, crustaceans and small fish that they catch in the water column.
Very little is known about the proliferation of tube anemones, but what seems to be sure is that fertilization takes place externally, with male and female individuals releasing their gametes into the water and all small or young individuals are born male and some of them become female after a certain age or when they reach a certain size. They are very long-lived, many tube anemone individuals reaching 100 years of age, maybe even more.