Giant Triton

Carefully and effectively. The triton tracks a crown-of-thorns starfish by scent across the reef, then moves onto it, using its large muscular foot to hold the starfish down and its shell as a shield against the toxic spines. It everts its long proboscis, rasps a hole through the starfish's body wall with a file-like radula, and secretes saliva containing compounds that appear to paralyse or subdue the prey, then feeds on the soft tissue inside. A single triton can consume a large starfish over a day or so. It is one of the very few predators that will take on the crown-of-thorns at all, since most animals avoid the spines and the toxins.

Not on its own, but it may be part of the picture. A giant triton eats only a handful of starfish a week, so even a healthy triton population cannot mop up a full outbreak of tens of thousands of animals. However, experiments have shown that crown-of-thorns starfish detect and actively move away from the smell of a triton, so a good density of tritons may keep starfish spread thin and stressed and make it harder for an outbreak to get started. This has led researchers on the Great Barrier Reef to investigate captive-breeding giant tritons and using triton scent as a tool to disperse aggregating starfish.

Yes, and the practice is ancient and widespread. Cutting or breaking a small hole near the pointed tip of the shell turns the whole spiral into a natural horn that produces a loud, carrying, low note when blown, and different cultures around the tropical oceans have used triton and conch shells this way for millennia, as war and hunting signals, to call people together, in religious ritual, and as musical instruments. The horagai of Japan, the shankha of India, and the pu of Hawaii are all shell trumpets, some made from the giant triton and some from other large sea snails. The species name tritonis and the common name Triton's trumpet come from the Greek god Triton, usually shown blowing a twisted shell.

Decades of collecting. The shell is large, glossy, and elaborately patterned, and it has been taken in great numbers for the curio and shell-decoration trade, sold whole in tourist markets across the tropics. Because the giant triton grows slowly, lives at naturally low density, and is easy for a diver to spot and pick up, populations were thinned out on many accessible reefs faster than they could recover. The consequences for crown-of-thorns dynamics, combined with the animal's own scarcity, led a number of countries to ban or restrict its collection, and it is slowly returning to some protected reefs.