Blue Glaucus

Laney Herman

Kingdom: Animalia

Phylum: Mollusca

Class: Gastropoda

Order: Nudibranchia

Family: Glaucidae

Genus: Glaucus

Species: Atlanticus

Introduction

The Glaucus atlanticus is known by many names such as the blue dragon, sea swallow, or blue angel. This species is a type of sea slug (nudibranch) and is easily recognizable due to its bright and vibrant blue coloring. Even though these animals rarely grow up to 3 cm long, they can pack a punch with their venom. They have the ability to swallow air and keep an air bubble in their stomachs to stay afloat. Blue dragons have a tendency to float upside down on their back as a camouflage tactic to avoid predators from above and below. The brightly colored blue and white underbelly blends in with the ocean and the greyish backside of the animal looks like the reflective light from below.

Physical Characteristics

This species has 6 appendages that feather out into finger like cerata at the ends with a tapered flattened body. These cerata do most of the stinging when threatened or finding prey. They also have serrated radular teeth for feeding on their large prey. Usually they like to just float and rely on the ocean waves and currents for movement but when needed they can also swim around on their own very slowly.

Habitat and Diet

Blue dragons can be located all over the world and inhabit the Atlantic, Pacific, and Indian oceans. They are also a pelagic species which means they don't dwell at the ocean surface or the ocean bottom but in open waters. Due to recent reports and sightings, it seems they have expanded past their normal habitat and have been seen in places such as the Australian east coast, European waters, and the east and south coasts of Africa.

Despite their very small size, their usual prey is much larger than they are. They are a foraging predatory species and their favorite meal is the very venomous Portuguese man o' war. Other prey includes the blue button jellyfish and they even are commonly known to resort to cannibalism when needed.

Venom

The Blue glaucus is an extremely venomous and deadly species. They don't create their own venom but they gain it from their prey. To do this they store and then concentrate the stinging nematocytes and toxic chemicals from the man o' war's long tentacles which can reach up to 30 ft long. There are hard discs located in their skin along with a protective layer of mucus to protect them from their prey's sting. When a predator comes along they can utilize their stored venom to deliver a strong and effective sting that is even stronger than the man o' war's. Symptoms of their sting include immediate and severe pain, nausea, and vomiting. Because of their free-floating nature and very small size, humans should stay cautious near oceans to avoid contact. Even after they die their venom still is present and active on their skin.

Reproduction and Lifespan

The lifespan of a Blue glaucus ranges from a month to a year. Similar to all nudibranchs, blue dragons are hermaphrodites so they produce sperm and eggs. They cannot however fertilize their own eggs. A mate is needed to create viable eggs for reproduction. Their white-colored eggs have an elongated spiral shape and are typically left to float freely or on other free-floating surfaces. They are also known to usually lay their eggs on the carcasses of their prey. Individuals will typically lay strings of 12 to 20 eggs. When mating they have to be careful of stinging each other so to help prevent this they have S-shaped penises.

Threats to the Species

Due to their growing popularity, especially on the internet, humans have started to become a huge problem for this species. Their vibrant, attractive look and color have increased the exotic pet trade for them as more and more people want them in their aquariums at home. Because they have a specific diet of mostly Portuguese man o' war, which are nearly impossible to obtain, they often are starved or aren't given the right nutrition or care.

Other large threats to the species are global warming and water pollution. Ocean acidification caused by the increase of CO2 in the atmosphere is a huge problem that commonly affects many marine species. Following the food chain, many species that the man o' war mainly feeds on have rapidly decreased in numbers which directly affects the Blue glaucus populations. This species' cannibalistic behaviors when other food sources are low can also contribute to the decrease in population. Pollution also has a prominent presence in threatening this species. The foreign objects and toxins from trash thrown in the ocean can also be fatal for many species.

The conservation of this animal is very difficult to organize because of its pelagic nature. Little information about their population numbers and threat impacts makes it hard to assess the status of their species and individual populations worldwide.

Works Cited

“Blue Glaucus.” Oceana, 14 July 2022, https://oceana.org/marine-life/blue-glaucus/.

Pinotti, Raphael M., et al. “On the Occurrence and Ecology of Glaucus Atlanticus Forster, 1777 (Mollusca: Nudibranchia) along the Southwestern Atlantic Coast.” Anais Da Academia Brasileira De Ciências, Academia Brasileira De Ciências, 8 Apr. 2019, https://www.scielo.br/j/aabc/a/RRQPD6w8XGtXPNFcqQG635g/?lang=en.

Fiene, Cory Pittman & Pauline. “Glaucus Atlanticus Forster, 1777.” Glaucus Atlanticus: Main Page, 25 Nov. 2010, http://seaslugsofhawaii.com/species/Glaucus-atlanticus-a.html.

Emmit, et al. “Blue Glaucus Facts & Information Guide .” American Oceans, 20 May 2022, https://www.americanoceans.org/species/blue-glaucus/.

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