Some of the most astonishing life on Earth can also be some of the most dangerous. For instance, blue dragons, also known as sea swallows, blue angels, and blue ocean slugs, are a type of mollusk known as a nudibranch. These little creatures are extraordinary to look at, but don't touch: one sting can send you straight to the hospital.
De George, A. (2021). The Blue Dragon Nudibranch [Photograph]. The Illawarra Flame. https://www.theillawarraflame.com.au/science--nature/backyard-zoology-look-out-for-blue-dragons
Blue dragons can be found on the surface of the Atlantic, Pacific, and Indian oceans in temperate and tropical waters throughout the world. They spend most of their life floating upside along the surface, staying afloat by storing air bubbles in their stomach. The blue side of their body acts as camouflage against the backdrop of the ocean’s waves, while the pearlized silver side blends in with the bright ocean surface, hiding it from predators below. The bright colors of the blue dragon are an example of a phenomenon called countershading. These beautiful slugs stay very small, rarely growing larger than three centimeters long, or just over an inch.
Blue dragons are not born with their venomous traits, they actually obtain them from feeding on the extremely dangerous, Portuguese man o’ war. When the blue dragon eats the Portuguese man o’ war, it siphons off the man o’ war’s stinging cells, called nematocysts, and concentrates them in its own finger-like appendages. They can gather a large number of these cells which, making the blue dragons a greater threat to humans than the man o’ war. One sting can lead to nausea, pain, vomiting, acute allergic contact dermatitis, and post-inflammatory hyperpigmentation. The blue dragon also feeds on venomous siphonophores, the blue button, and the violet snail.
Perrine, D. (2019). Blue dragon sea slug (Glaucus atlanticus) and Portuguese man o’ war (Physalia physalis) [Photograph]. bioGraphic. https://www.biographic.com/deathly-beautiful/
Due to the blue dragon’s small size, little is known about its conservation status, but there are some factors that may be weakening their population. Researchers have said the exotic pet trade, pollution, and ocean acidification could all be affecting the blue dragon population. These factors would also affect their prey, which in turn affects the blue dragon.
Blue dragons travel together in groups called “fleets”, which helps them find mates and food. However, this makes them vulnerable to ocean winds, which can push them to the shore where they’ll die unless they get pulled back out by the tide. The blue dragon is a simultaneous hermaphrodite, meaning each individual has both male and female reproductive organs. After a pair mates, they will lay a string of about 16 eggs in the water, which will then take about three days to hatch into larvae.
Blue dragons are very astonishing creatures, with a small size and beautiful colors, but they can also be extremely dangerous and even fatal. Just remember, if you see a small sea dragon floating upside down along the ocean surface, don’t touch it!
About the Author
Laney is a sophomore at Northwood High School and is a member of their track and field team, mix up club, and unified club. She loves working with kids, being outside, and hanging out with friends and family.
Sources
“5 Interesting Things You Should Know about Blue Dragons.” Free the Ocean,
Kelly, Aidan. “Featured Creature: Blue Dragon | Blog | Nature | PBS.” Nature, 7 Aug. 2014,
Sargent, Channing. “Species of the Week: Blue Dragon.” One Earth,
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