Ascidia mentula
Ascidia mentula is a species of solitary tunicate. It is found in the north east Atlantic Ocean, the Mediterranean Sea and Black Sea. It occurs round the coasts of Britain but is seldom seen on the east coast of England or Scotland. Ascidia mentula has a tough leathery envelope or tunic composed partly of cellulose.
The translucent tunic encloses a fluid-filled body with irregular bulges and two unmistakable siphons. It is 5 to 18 cm (2 to 7 in) tall, bottle or flask-shaped with the oral (inlet) siphon at the tip and the six-lobed atrial siphon half to two thirds of the way down. The oral siphon has six to eight, often white-tipped, lobes and is surrounded by up to 100 branchial tentacles. It is usually red, pink or sometimes olive green in colour, and may be grey in deep water. It normally adheres to the substrate by the side opposite the atrial siphon.
Ascidia mentula is native to the north eastern Atlantic Ocean, its range extending from Norway southwards to the Mediterranean Sea and Black Sea. It occurs on rocky substrates at depths ranging from subtidal down to 200 metres (660 ft). It favours crevices and shady gullies and sometimes adheres to Laminaria holdfasts, stones and shells. Ascidia mentula feeds on plankton that it filters from seawater with a mucous net.
A small bivalve mollusc (Modiolarca Tumida) often lives within the tunic in the body cavity which may also be occupied by a small pea crab (Pinnotheres pinnotheres) and a copepod (Notopterophorus papilio). Breeding takes place mainly in the summer. Fertilization is external and the tadpole larvae spend a short time in the plankton before settling on the seabed, undergoing metamorphosis and becoming juveniles.
This video was shot during a scuba dive in the area between Livorno and Gorgona Island. We are over 12 nautical miles from Livorno and about 6 miles from Gorgona. In this area the seabed rises from over 100 meters deep to 48 metres. It is an area that we know well in the part between 48 and 54 meters deep, but the sea always reserves unexpected surprises: in fact from the echo sounder we saw that there are reef at depths of 60, 70 meters and more. The interesting thing is that these deep rocks have never been visited by divers and therefore we are the first to document the beauty of these seabeds.
However, to be able to document the seabed with the camera it is necessary to have good lighting because the sun’s rays arrive very weakly and the colors of the seabed tend to be uniform grey; the lights instead allow our camera to highlight the entire range of colors present in the coral reef. To be able to document the seabed with the camera it is necessary to have good lighting because the sun’s rays arrive very weakly and the colors of the seabed tend to be uniform grey; the lights instead allow our camera to highlight the entire range of colors present in the coral reef.
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