This drill is Morula fusca! Brian Ong kindly shared the id of this snail which I earlier posted on wildfacts sheets as 'awaiting identification'.Brian also kindly shared photos and information about this fascinating snail from a study that he did on them.
Brian shared that one of the identifying features of this snail is its yellow foot.
He adds that the shells are on average about 1.5cm long. He also shared many photos of them.
From his project on Morula fusca, Brian found them to eat Siphonaria false limpets! Morula fusca found on St. John’s Island, fed mainly on false limpets Siphonaria javanica and Siphonaria guamensis. They also rarely ate small bivalves and barnacles. In Brian's study, he found that Morula fusca were not selective about the size of their prey.
Like many others of the Family Muricidae, the snail drills a hole through the shell of the false limpet. Hence the common name for these snails! Although there many other snails also drill though their prey shells like moon snails (Family Naticidae) and whelks (Family Nassaridae). To bore a hole through the victim's shell, a drilling snail softens the shell with a weak acid secreted by a special gland on the underside of its foot. The softened shell is then slowly scraped off by the snail's radula. The radula is the main physical tool in creating the hole.
Brian shares that Morula fusca drill holes are countersunk, and he also found that larger Morula fusca snails drilled larger holes.
Brian shares that Morula fusca sometimes gets to its false limpet snack by slipping its proboscis under the shell of the false limpet without the need to drill though them.
He adds that Morula fusca are found on intertidal rocks and are usually packed into shaded areas such as crevices and cracks in the rocks.
The wild fact sheet about this snail has been updated with the photos and information that Brian shared. Thank you very much to Brian for sharing his hard work on these snails so that we can all learn more about them and our shores!
From Tan, K. S. & L. M. Chou, 2000. A Guide to the Common Seashells of Singapore. BP and Singapore Science Centre, this snail lays stalked, globular egg cases. Tiny crawling juvenile snails emerge from these egg cases. This snail has a patchy distribution in Singapore but can be common where it occurs.
Tan, K. S. & L. M. Chou, 2000. A Guide to the Common Seashells of Singapore. Singapore Science Centre. 160 pp.