Karst ecosystem: Ophiphistoma vermiculum_FoonJunnKit

Minute Land Snail (Opisthostoma vermiculum)

Species: Opisthostoma vermiculum (Gastropoda: Diplommanitidae)

Known Range: Gunung Rapat limestone hill, Malaysia

Size: (Adult) 1.0 – 1.5 millimeters

Interviewed: Foon Junn Kitt, malacologist

(Photo: Opisthostoma vermiculum by Foon Junn Kitt)

HOW IS this a snail, and not just a tiny, whitish, swirly plastic tube? Even its species name, vermiculum, means ‘wormy’ in Latin, which aptly describes the snail’s shell.

There must be something special about the evolution of the Minute land snail O. vermiculum, says snail expert Junn Kitt.

Discovered and named in 2008, the Opisthostoma vermiculum is the only snail known to grow a shell that turns around four axes. All other snails grow shells with fewer axes.

How a snail grows a twisted shell

The snail sent surprised experts into a pleasant spiral. They named O. vermiculum one of the most wonderful discoveries in 2008/2009.

Junn Kitt describes the impact that O. vermiculum made.

Unexpected twists in a shell

The snail was discovered in Gunung Rapat, near Ipoh, Malaysia. It has not been found elsewhere, despite “vigorous attempts”, says Junn Kitt.

Such rarity and uniqueness should crown O. vermiculum a Perak state treasure, if not a national one. But how many Malaysians know about it?

The snail came to light when biologist Dr Reuben Clements sifted through leaf litter in the grounds of a temple at the foot of limestone hills at Gunung Rapat. Reuben found only shells.

Junn Kitt recalls Reuben’s discovery.

Treasure in the dirt

Live O. vermiculum was found in the same site years later by snail expert Dr Liew Thor Seng. The snail likely feeds on fungi and other organic matter in the leaf litter. Other members of Opisthostoma grow from egg into adult in two weeks.

Junn Kitt describes how finding tiny snails can get bloody at times.

When snail-hunting becomes a feast for mosquitoes

The snail is categorised as Critically Endangered in the IUCN Red List. That’s mainly because it’s found in only one place. So far, the temple ground is a haven for the snail, says Junn Kitt.

However, that might not always be the case. Numerous quarry operators nearby mine limestone hills.

This is of concern, as aside from the structure of its shell, we know almost nothing about O. vermiculum.

An important next step is to study the snail in the wild. That would lead us to an understanding of not just the snail’s biology and evolutionary history, but also the ecosystem it lives in.

The last point is pertinent because snails are important players in ecosystems, says Junn Kitt. As detritivores, snails break down organic matter and help move nutrients in the environment.

Further Reading

G.R. Clements et al. 2008. Further twists in gastropod shell evolution. Biology Letters 4: 179-182.

J.K. Foon et al. 2017. Diversity and biogeography of land snails (Mollusca, Gastropoda) in the limestone hills of Perak, Peninsular Malaysia. ZooKeys 682: 1-94.

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