Glaucus atlanticus

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I chose to write my blog about animals that I find cool. The first animal that I have chosen to write about is the Glaucus atlanticus. The more common name for this species is the blue sea slug or the blue dragon. Being an invertebrate means that it has no bone structure. given that it lives in the water which is denser than air gives support to its softer body type. It spends its life floating upside down on the surface of the ocean. It feeds mostly on other invertebrates floating in the water but will occasionally eat from its own species. It floats upside down in the water because of its coloration which acts as camouflage. The blue dragon is blue and white on its belly to blend in with the sea to hide from top side predators such as sea birds and silvery on its dorsal side to hid from other fish below. The blue dragon has another defense mechanism to protect it from predators in the form of venom. The blue dragon stores poison from its prey such as the Portuguese man of war in its own tissues that stick out form its body so that it can sting predators. It is able to eat such poisonous prey because it is completely immune to the poison The way that the blue dragon is able to stay on the surface of water is with an air bubble that it has in its stomach. The blue dragon does not swim but is carried along by currents and wind. It has some ability to direct itself towards prey but mostly just goes along for the ride. The blue dragon is found in the tropical waters of the atlantic, pacific, and indian oceans. It can grow to be about three centimeters long. The blue dragon also has both male and female reproductive organs. Both organisms involved in mating will lay eggs that float along the surface. The larva of the blue dragon has a shell, but eventually loses it.  The blue dragon is not seen often, but can wash up close to shore, and their sting can affect humans. The sting can cause problems with the heart and lungs, fever, and shock, and in severe cases death.


Jameson-Gould, J. (2011, July 13). Blue sea slug. Retrieved September 8, 2016, from

Glaucus atlanticus- the blue dragon. (2013, April 15). Retrieved September 8, 2016, from

2 thoughts on “Glaucus atlanticus

    dss2000 said:
    September 22, 2016 at 2:00 am

    I found this very interesting as I have never seen a sea creature with such color and abilities. Do you know where in the world they are most common and how long they have exsisted? Also, how long is their life spans?

      jmm1054 responded:
      September 26, 2016 at 3:20 pm

      It is most common in the Atlantic, Pacific, and Indian oceans. It was discovered in 1777. They can live up to a year.

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