Halocynthia papillosa is a solitary ascidian which is generally 10 cm high but
may reach 20 cm. The body is ovoïd, the red test is cartilaginous, rough with a granulous surface.
The siphons are distant: the oral siphon is terminal and the atrial siphon is half-way down the body.
Rigid bristles, used as sensitive elements, surround the siphons. The red sea-squirt can contract and
close its siphons when disturbed.
It lives attached to rocks, overhangs or among Posidonia, avoiding luminous areas, between 2 and 100
meters deep. It is a Mediterranean species that may live in the surrounded Atlantic Ocean, particularly
along the Portuguese coasts.
Phylum Chordata, subphylum Tunicata, class Ascidiacea, order Stolidobranchia, family Pyuridae, Halocynthia papillosa (Linnaeus, 1767).
Test: or tunic: thick layer secreted by the mantel containing cellulose and protecting the animal.
Oral siphon: Opening by which water is drawn in the ascidian.
Atrial siphon: Opening through which water is expelled.
Photograph: © Wilfried Bay-Nouailhat. Published with author's kind permission.
Halocynthia papillosa, Illes Medes, Costa Brava, East of Spain. Depth 15 meters.
Text: Anne Bay-Nouailhat © 2005-2008.
Translation: Anne Bay-Nouailhat © 2007-2008.
