the Giant Triton. It is usually found among corals on coral reefs. On the Great Barrier Reef it tends to occur on seaward slopes or on coral pinnacles in lagoons (20). It is usually nocturnal (19) but in Indonesia has been recorded from sand near coral in broad daylight (22). It feeds principally on starfish including Culcita novaeguinea the blue starfish Linckia laevigata and the Crown-of-thorns, Acanthaster planci but also occasionally on holothurians (2,15,20,21). When preying on A. planci it takes mainly large juveniles and adults on which it may feed whole (4,5,15). It may take up to six years to reach its maximum size (3). It has been reported that the female lays clumps of sausage-shaped egg capsules under protective rocks. The larvae are long lived and have considerable dispersal abilities (3,23,2f). SCIENTIFIC INTEREST AND POTENTIAL VALUE The shells of this species have been used as a trumpet in the South Sea islands, Indonesia, Hawaii and the Seychelles for centuries (3). More recently it has become one of the more sought-after shells in the ornamental shell trade and is collected in large numbers in the Philippines and other countries (6,17). It has been collected extensively in Queensland waters since World War II and available evidence indicates that thousands of specimens were collected on the Great Barrier Reef during the 1950s and sold to tourists and to the shell trade via the commercial trochus shell dealers on Thursday Island in the Torres Straits (7). Shells were collected intensively at several islands in the Marianas and Carolines in the 1960s (18). In 1970 a thousand specimens were seen on sale in Suva market, Fiji said to have come from remote islands (10) and in 1971 specimens were seen on sale at several localities on Manus Island, Papua New Guinea (7). Heavy collection was reported in this area in the 1970s. In Hawaii in 1971, shells were on sale for U.S65 each. The value in 1978 was put at U.S7-30 depending on size and quality (16). In 1981 specimens in the Philippines sold for U.S5-20 (17). It has been suggested that C. tritonis may be a key species in the coral reef community. As a predator of the Crown-of-thorns Starfish it was thought to be important in keeping this species in check (7). Its role in this context was hotly disputed at the peak of the Acanthaster outbreaks in the Indo-west Pacific, and no final conclusion has been reached, as several other factors are almost certainly involved. Specimens of C. tritonis do not appear to be sufficiently common to exert any control over A. planci populations, and starfish attacked by the mollusc have been found to survive (7,15). Furthermore, C. tritonis may prefer other species of starfish (21). However, areas with particularly low numbers of C. tritonis have been found to correlate with infestations of the Crown-of-thorns (f5,7,20). THREATS TO SURVIVAL Over-collection may have been responsible for reports of depletion of this species in some areas. Furthermore, the large numbers taken strongly suggest that populations may have declined. Populations have been severely decimated by over-collecting in Guam waters (8) and the species is said to be vulnerable to collecting in southern Japanese waters (9). Some shell dealers in the Philippines reported Giant Tritons to have become scarce in 1981 (17). At the end of the 1960s C. tritonis was reported to be common in Palau and Rota in the Pacific, areas which were seldom visited by collectors (15). In the Caribbean, a similar species, the Variegated Triton C. variegata has also been depleted through over-collection (13). However, despite these reports, this species, although certainly rare, may not be threatened at present. Its wide distribution and prolific long-lived larvae would suggest that it may be able to support current collecting pressure (2f). Like many other species C. tritonis populations could have been reduced as a result of the accumulation of toxic residues from pesticides and other pollutants in the tissues of specimens, particularly since this species is a predator of high trophic status (f7) but there is no data to substantiate this. 92