We are on a mixed seabed made up of sand, debris, mud and some rocks between 44 and 52 meters deep. On the bottom before reaching the cliff we wanted to explore we found the Cerianthus Membranaceus or Tubular Anemone. The peculiarity of this species of anemone is that it has two orders of tentacles, the first external with dimensions up to 40 cm, and an internal one of reduced dimensions, in our case of white color, which serves to bring the food directly to the central mouth.
Other characteristics of the tubular anemone are the fact of creating a calcareous tube and therefore the impossibility of making those small movements that other types of anemone can do; and the various colors that can have, white, yellow, orange, green, brown, blue, black, purple, the external spiral. The color of the inner spiral often contrasts with that of the outer spiral.
Cerianthus membranaceus, l’Tubular anemone cilindrico o Cylinder anemone, is a species of large, tube-dwelling anemone in the family Cerianthidae. It is native to the Mediterranean Sea and adjoining parts of the northeastern Atlantic Ocean.
Cerianthus membranaceus is a large, tube-dwelling anemone. The oral disc can have a diameter of up to 40 cm (16 in). There are two whorls of tentacles, amounting to about two hundred tentacles in all. Those in the outer whorl are long and slender and armed with cnidocytes (stinging cells) and are used for catching prey. Tentacles in the inner whorl are shorter and function to transfer captured food to the central mouth. The tentacles are sometimes banded and come in an array of colours; white, yellow, orange, green, brown, blue, black, purple and violet. The colour of the inner whorl often contrasts with that of the outer whorl.
The column of this tube anemone secretes mucus in which is embedded a unique type of cnidocytes that mesh together to form a fibrous structure. Sand and other particles adhere to this and it forms a leathery, protective tube up to 40 cm (16 in) in length. There is no pedal attachment and the lower end of the tube is buried in the soft substrate. The tube is open at the base which allows for escape of water when the animal retreats into the tube.
Distribution and habitat
Cerianthus membranaceus is found on the seabed in shallow water in the Mediterranean Sea, the northern Adriatic Sea and the northeastern Atlantic Ocean, its range extending as far north as Britain. It occurs on sandy or silty substrates where its tube is buried vertically in the sediment. In the Mediterranean, it principally occurs in areas with high levels of organic matter, such as in zones of pollution off Marseille, where it is present at high densities throughout the year.