Charonia Research Digital Collection New

 

Miyake-Jima 1957

It's 1957 and Japanese scientists travel to the island of Miyake-Jima to study a strange disease affecting a coral reef. The island’s people have noticed a strange increase in the number of the large, venomous crown-of-thorns starfish. Over the following years they kill large numbers of the starfish attempting to protect the living coral upon which the starfish is feeding. The Japanese scientists noted that they had observed giant triton shells feeding on the crown-of-thorns starfish, in research published only in Japanese.

5 years later

This same species of starfish is noticed in increasing numbers at Green Island, off Cairns here in Australia. Over the next five years, the starfish outbreak will consume much of the living coral at Green Island and other reefs in the vicinity.

The giant triton is again observed feeding on crown-of-thorns starfish and research in Queensland is commenced on the feeding rate and prey preference of the giant triton. Tests are done with three species of starfish; multiple specimens of each species are placed in cages with giant tritons.

The results showed that while each giant triton ate one crown-of-thorns starfish per week on average, it ate less crown-of-thorns starfish than another relatively common species of starfish. The research concluded that the crown-of-thorns starfish was not the preferred prey of the giant triton.

This conclusion was further supported by similar research done overseas, despite the observation that giant tritons were often located on the Great Barrier Reef, and elsewhere, were eating crown-of-thorns starfish.

30 years later

It becomes apparent that such a conclusion about prey preference of the giant triton is simply not justified, given the crown-of-thorns starfish often escapes complete predation because of its relatively high mobility. It is apparent that there is much confusion between prey capture and prey preference of the giant triton. It is suggested this distinction is relevant to control of prey.

40 years later

Australia is unsuccessful in its attempt to list the giant triton in Appendix 2 of the Convention in Trade in Endangered Species (CITES) because Japan objects on the grounds of ‘no evidence’ for the alleged endangered status of giant triton.

50 years later

The Great Barrier Reef Marine Park Authority reports that outbreaks of crown-of-thorns starfish are a threat to the Great Barrier Reef and controls are needed.

60 years later

While the giant triton may be protected on the Great Barrier Reef and elsewhere in Queensland, there is still no evidence this protection has resulted in restored populations of the giant triton. However, there is evidence of continuing illegal collection and trade in Indonesia where it is also legally protected.

It is now worth reconsidering whether the existing local protection is sufficient or whether further international protection is required by listing the Giant Triton in Appendix 2 of the Convention on International Trade in Endangered Species (CITES).

The giant triton (Charonia tritonis) is a beautiful shell and a well-known predator of the crown-of-thorns starfish (Acanthaster planci). In many parts of the third world, it is still being collected in large numbers and sold to tourists as ornaments. As you admire the beautiful shell, spare a thought for the hungry mollusc that died. And don’t forget, they live on starfish. Many species of starfish are known to outbreak in different parts of the world. Prior to human collection, the giant triton might have controlled starfish numbers not by eating the many, but by preventing the aggregation that precedes the outbreak. At present, little is known of any aspect of the triton’s ecology despite its obvious importance in controlling starfish numbers.