A rose coral colony stretching 1.56 kilometres along the outer reef of the Cocos (Keeling) Islands has been mapped by researchers and is one of the largest coral colonies ever recorded.
The work was announced by Queensland Museum, which described the formation as the equivalent of approximately 100 buses parked end to end.
The colony occupies the outer reef slope between depths of 14 and 65 metres. It averages 36.5 metres wide and covers 56,940 square metres, an area the museum compared to more than three MCG playing areas.
Further sections extend between 200 and 300 metres beyond the main body.
Mapping took 12 dives over several months. Divers used GPS to mark where each dive ended, so that the next could pick up from the same point along the reef.
Dr JP Hobbs of Adelaide University led the research, working with Queensland Museum and James Cook University.
The coral was not unknown locally. A dive operator on the islands first noticed extensive areas of it more than 30 years ago. What the survey added was the realisation that the separate stretches may be connected.
That is the open question, and it is a large one. Researchers are now using genetic testing to investigate whether the formation is a single organism or several colonies fused together.
The result is a set of measurements of unusual precision attached to a subject of unusual vagueness. The length is 1.56 kilometres. The average width is 36.5 metres. The area is 56,940 square metres. The number of animals is unknown.
This newspaper notes that one figure in the announcement is not in doubt at all. The colony is 100 buses long. Buses are a settled quantity. They are built to specification, they do not fuse, and nobody has ever had to sequence one to establish how many there are.
Our analysts therefore propose treating the buses as the stable unit and the coral as the variable. On present evidence the formation is definitely 100 buses and somewhere between one and many corals.
The upper bound follows from the comparison itself. If the stretches turn out to be separate animals, the most generous reading allows one coral per bus length, which would be a tidy outcome and the first occasion on which marine taxonomy has been settled by public transport.
No bus has been allocated more than one coral. Pending the genetics, the distribution appears even.
The Department of Unnecessary Research has asked Queensland Museum for the only clarification that would resolve the matter. If the colony is one organism, it is a single animal the length of 100 buses. If it is 100 organisms, it is a traffic jam.