Phallusia nigra is a solitary marine tunicate of the ascidian class found in tropical seas around the world. It usually lives in shallow waters, attached to any hard substrate.[2][3]
Like all tunicates, P. nigra has a thick leathery envelope (tunic) containing cellulosic material. Like all solitary ascidians, the tunic encloses a sac-shaped body with separate water entrance and exit tubes (siphons). It lives on plankton that it filters from seawater with a mucous net. This tunicate is often host to the small symbiotic pea crab Tunicotheres moseri which takes up residence in its atrial chamber.[4]
An adult P. nigra may be 10 cm (4 in) long. The tunic is usually velvet black or dark brown, but may be gray in specimens that are younger or live in shaded areas. Its original range is unclear; the tropical Western Atlantic Ocean, the Red Sea, and the Indian Ocean have been proposed.[2]
The tunic of P. nigra contains many vesicles filled with a strong acid (with pH near 1), containing mostly sulphateSO 42− and chloride (Cl− ) anions. The vesicles are concentrated towards the outer surface and are easily ruptured by contact; they are believed to protect the animal from predation and fouling.[5]
^Lopez Greco, L.S.; Bolanos, J.; Rodriguez, Marcelo; Hernandez, G. (2001). "Survival and Molting of the Pea Crab Larvae Tunicotheres moseri Rathbun 1918 (Brachyura, Pinnotheridae) Exposed to Copper". Archives of Environmental Contamination and Toxicology. 40: 505–510. doi:10.1007/s002440010203.
^Costa, LV; Malpezzi, EL; Matsui, DH; Machado-Santelli, GM; Freitas, JC (1996). "Cytotoxic activity of a methanol extract of Phallusia nigra (Tunicata, Ascidiacea)". Brazilian Journal of Medical and Biological Research. 29 (3): 367–73. PMID8736132.
^Costa, Letı́cia V; Malpezzi, Elena LA; Berlinck, Roberto GS; Rowan, Edward G; De Freitas, José Carlos (1997). "This Histamine-Like Effects of Phallusia nigra Extract: Evidences for Direct Activity at H1 Receptors". Comparative Biochemistry and Physiology C. 117 (1): 111–5. doi:10.1016/S0742-8413(96)00228-9. PMID9185333.