© Copyright 2006 Andrew Trevor-Jones

Chambered nautilus, Nautilus pompilius, from the Coral Sea.

Nikon D70, Nikkor 18-70mm, Ikelite housing, dome port, DS50 and DS125 strobes.

ISO200, 1/160s, f/16 @ 34mm

Chambered nautilus have hardly changed since the time of the dinosaurs. At one time, nautilus and related cephalopods were the dominant marine predators. Nautilus are now mostly scavengers. During the day they spend their time in deep water (500-600 metres) at the base of tropical reefs. At night they move into shallower water (200-300 metres) to scavenge for food, usually the bodies of dead animals that have fallen down the reef walls.

The pictured animal was captured by Underesea Explorer as part of their Nautilus Research . They trap nautilus at a site called Admiralty Anchor on the western side of Osprey Reef in the Coral Sea. The traps, baited with chicken pieces, are dropped down the reef wall to a depth of 200-300 metres (the lines are 300 metres long) and leave the traps overnight. The traps are raised the next morning and any captured nautilus are transferred to holding tanks. The tanks are chilled with plastic containers filled with ice to keep the water temperature closer to what they would experience in deep water.

The researcher on board the boat measures, logs and engraves each animal and they are released that night back at the same site. The trapping and handling does not appear to have any adverse effect on the animals and Undersea frequently recapture tagged animals.

The research is important in understanding the populations at Osprey Reef so they can be protected from shell collectors.