The blue dragon sea slug, Glaucus atlanticus, is a striking marine creature known for its vibrant coloration and unique appearance. Despite its captivating beauty, this small sea slug harbors a potent defense mechanism that can deliver a painful sting to unsuspecting humans. Encountering these creatures, especially when they wash ashore, often prompts questions about their potential danger.
Meet the Blue Dragon
The blue dragon is a type of nudibranch, a shell-less marine gastropod mollusk, also known as the blue glaucus or sea swallow. It typically measures around 3 centimeters (1.2 inches) in length, though some individuals can grow slightly larger. Its distinctive appearance features a flat, tapering body with six appendages that branch into rayed, finger-like cerata. The slug displays a brilliant blue and silver coloration, with its blue side facing upwards to blend with the ocean’s surface, and its silvery-grey side facing downwards to camouflage against the sunlight when viewed from below.
This creature lives in the pelagic zone, meaning the open ocean, where it floats upside down on the water’s surface. It maintains its buoyancy using a gas bubble stored in its stomach. Blue dragons are carried along by winds and ocean currents, which can sometimes lead to them washing ashore on beaches worldwide, particularly in tropical and temperate waters of the Atlantic, Pacific, and Indian Oceans.
How They Become Dangerous
The blue dragon’s danger stems from its specialized diet and a process called kleptocnidae. This sea slug primarily preys on other venomous marine organisms, most notably the Portuguese Man O’ War. Unlike many other creatures, the blue dragon does not produce its own venom. Instead, it consumes its prey and ingests their undischarged stinging cells, known as nematocysts, without being harmed.
The blue dragon then stores these collected nematocysts in specialized sacs, called cnidosacs, located at the tips of its finger-like cerata. By concentrating these stinging cells, the blue dragon can deliver a sting more potent and painful than that of the Portuguese Man O’ War. When threatened, the blue dragon releases these concentrated stinging cells, making direct contact a risky proposition.
What to Do If Stung
A blue dragon sting can cause discomfort and a range of symptoms. Common reactions include intense pain, burning, nausea, and vomiting. Skin irritation, such as redness, bumps (papules), blisters, and allergic contact dermatitis, may also occur. Dizziness or post-inflammatory hyperpigmentation, a darkening of the skin that can persist for weeks, are also possible.
If stung, rinse the affected area with seawater, not fresh water, as freshwater can cause more stinging cells to discharge. Carefully remove any visible stinging cells or pieces of the slug using tweezers or the edge of a card, avoiding direct contact. Applying heat to the sting site can help alleviate pain by denaturing the venom; immerse the area in hot water (42-45°C or 110-113°F) for 20-45 minutes, or use a hot pack if water is unavailable. Seek medical attention if symptoms are severe, such as difficulty breathing, widespread rash, dizziness, or if the pain persists or worsens.
Safe Encounters
Observing blue dragons from a safe distance is the most effective way to avoid a sting. If these creatures are encountered on a beach or in the water, refrain from touching them. Even if a blue dragon appears dead, its stinging cells can remain active and deliver a painful sting.
Awareness of ocean conditions and local warnings is also beneficial, especially during times when marine life might be washing ashore due to winds or currents. Blue dragons are captivating, but their defense mechanism necessitates caution. Admire their unique beauty without direct contact.