Phallusia nigra
Encyclopedia
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.
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.
An adult P. nigra may be 10 centimetres (3.9 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.
The tunic of P. nigra contains many vesicle
s filled with a strong acid (with pH
near 1), containing mostly sulphate 2− and chloride
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
.
Substances extracted from the dried tunic with methanol
have been found to have cytotoxic, antibacterial, antipyretic
, analgesic
, and histamine
-like activity.
Tunicate
Tunicates, also known as urochordates, are members of the subphylum Tunicata, previously known as Urochordata, a group of underwater saclike filter feeders with incurrent and excurrent siphons that is classified within the phylum Chordata. While most tunicates live on the ocean floor, others such...
of the ascidian class found in tropical seas around the world. It usually lives in shallow waters, attached to any hard substrate.
Like all tunicates, P. nigra has a thick leathery envelope (tunic) containing cellulosic
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
material. Like all solitary ascidians, the tunic encloses a sac-shaped body with separate water entrance and exit tubes (siphons). It lives on plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
that it filters from seawater with a mucous
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
net.
An adult P. nigra may be 10 centimetres (3.9 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
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
, and the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
have been proposed.
The tunic of P. nigra contains many vesicle
Vesicle
Vesicle may refer to:In cellular biology or chemistry* Vesicle , a supramolecular assembly of lipid molecules, like a cell membrane* Synaptic vesicleIn human embryology* Auditory vesicle* Optic vesiclesIn human anatomy and morphology...
s filled with a strong acid (with pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
near 1), containing mostly sulphate 2− and chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
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
Epibiont
An epibiont is an organism that lives on the surface of another living organism. An epibiont is usually considered harmless to the host; in this sense, the relationship between the two organisms can be considered neutralistic or commensalistic. Typical epibionts are barnacles, remoras, and algae,...
.
Substances extracted from the dried tunic with methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...
have been found to have cytotoxic, antibacterial, antipyretic
Antipyretic
Antipyretics ; an-tee-pahy-ret-iks; from the Greek anti, against, and pyreticus, are drugs or herbs that reduce fever. Normally, they will not lower body temperature if one does not have a fever. Antipyretics cause the hypothalamus to override an interleukin-induced increase in temperature...
, analgesic
Analgesic
An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....
, and histamine
Histamine
Histamine is an organic nitrogen compound involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter. Histamine triggers the inflammatory response. As part of an immune response to foreign pathogens, histamine is produced by...
-like activity.