In the diverse world of the ocean, every species plays its own role in maintaining ecological balance. However, when a species grows beyond its natural threshold, it can quickly turn into a threat to the entire ecosystem. The Drupella cornus snail—small and unassuming—is a clear example. Despite its tiny size, this coral-eating snail can cause serious damage to coral reefs when its population is not controlled.
MAIN CONTENTS
1. Drupella Cornus Through the Lens of Marine Ecology
Drupella cornus belongs to the Muricidae family—a group of spiny marine snails widely distributed across the Indo-Pacific region, including Vietnam’s coastal waters. Measuring only 1.5–4 cm, Drupella has a thick shell covered in sharp spines, with colors ranging from grey, pink, green to brown, allowing it to blend seamlessly among coral branches.
This species is most active at night. Using a tube-like mouthpart, Drupella scrapes and feeds on live coral tissue, leaving behind pale, exposed skeletons—an unmistakable sign of predation. When gathered in groups, they can strip an entire coral cluster in a short time, especially on fragile or environmentally stressed reefs.
Drupella’s natural predators include Wrasses, Pufferfish, Triggerfish, Emperor fish, and some large crabs. However, when these predator populations decline due to overfishing or ecosystem imbalance, Drupella can multiply rapidly—leading to what scientists call a Drupella outbreak.
2. When Coral Reefs Grow Weaker – Drupella Takes Over
During OnBird’s reef monitoring around Phu Quoc, our team encountered traces of Drupella presence. Normally, a healthy reef can tolerate small numbers of Drupella without significant damage. But when environmental changes occur—warming seas, pollution, sedimentation, or coral bleaching—the coral’s protective mucus layer becomes weakened. This creates ideal conditions for Drupella to attach, reproduce quickly, and form dense aggregations.
Drupella can feed on most coral species, but delicate branching corals such as Acropora and Pocillopora are among its preferred targets.
In Phu Quoc, early signs of Drupella predation have been observed in areas involved in coral restoration projects—such as Coral Nursery and Transplantation Sites managed by OnBird. While the damage has not yet escalated, Drupella could become a serious threat to young, developing coral colonies if not addressed in time.
Early detection and population control are therefore essential parts of OnBird’s routine reef monitoring efforts—helping protect the Coral Nursery and maintain ecological balance across the restoration zones.
3. Drupella Control Efforts at OnBird Phu Quoc
Regular surveys and monitoring
Our team is trained to quickly identify Drupella signs and assess their density during reef surveys. These observations are recorded regularly to track population trends and pinpoint areas at risk of outbreaks.
Careful, manual removal
When Drupella densities exceed safe thresholds, our divers conduct manual removal. This requires advanced skill, as the snails often hide deep within coral branches. The goal is to remove them completely while minimizing disturbance to young or fragile coral structures.
Protecting predators and maintaining a healthy food chain
An essential part of Drupella control is protecting its natural predators—especially Wrasses and Triggerfish. OnBird encourages visitors not to feed or disturb reef fish and never to harvest species that play a key ecological role.
By helping guests understand the function of each organism—including those perceived as harmful—we foster deeper appreciation and more responsible interaction with the ocean.
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4. Working Toward Natural Balance
Drupella is not the “enemy” of the sea. In a healthy ecosystem, they are part of the natural cycle of coral growth and decomposition. It is only when the environment becomes imbalanced—weak coral, loss of predators, or rising sea temperatures—that Drupella turns into a threat.
This is why every small effort matters — from simple safety reminders, daily sea-weather monitoring, and careful risk management to the awareness each visitor brings — collectively make a meaningful difference. Together, they help sustain a more balanced, resilient, and vibrant ocean.
We hope this article provides you with a deeper and more interesting perspective on the ocean. Follow OnBird – Soft-Adventure Journeys to discover more marine species that keep Phu Quoc’s underwater world alive and ever-evolving!
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