Discoveries in ocean biodiversity ruled the 19th century. Circa 1890, Leopold and Rudolf Blaschka were rapidly crafting astounding masterpieces in glass, with an eventual output of over 10,000 models. In my book, A Sea of Glass, I chronicle my quest to find the living matches to the glass models. One of the most beautiful of these is the blue dragon; an absolutely tiny, ¼ inch long seaslug that swims the open ocean in search of its prey. It selectively hunts and eats the huge and lethal, Portuguese man of war, a jellyfish relative. It not only eats it, but also ingests and re-uses the tiny, immature cells of the stinging organelles known as nematocysts that will grow into lethal, venom-filled harpoons that can kill humans.
Glaucus atlanticus, the living match (Caption 2) to the Blaschka’s blue dragon, sails the seas with what Sir Alistair Hardy famously described many years ago as “The Blue Fleet.” This unusual fleet is comprised of three species of the blue-pigmented siphonophore jellyfish: Physalia, Velella, and Porpita. Amazingly, all of them were also crafted in glass by the Blaschkas and I show them below in glass (Caption 3). These pelagic travelers float on the surface of the ocean being carried by the currents and the winds.
Glaucus feeds only on this group of jellyfish, and as Tom Thompson and Isobel Bennett reported some years ago, it appears that they are able to select the most venomous of Physalia’s stinging nematocysts for their own use. Like most aeolid nudibranchs, their digestive systems extend into the flap-like projections off their backs (cerata), where they can store the consumed and still dangerous nematocysts in special sacs (cnidosacs).
At around the same time in late 1890, Prince Albert I of Monaco, who founded Monaco’s Musee Oceanographique, was leading expeditions to discover the riches of the oceans aboard his sailing ship, The Princess Alice. Not only is the blue dragon stunningly portrayed in both glass and water color by the Blaschkas, it is also sketched in watercolor by Prince Albert I’s artist, Le Roux Jeanne. When I visited the amazing exhibition about Prince Albert I’s expeditions in Musee Oceanographique this fall, I took a picture of the watercolor of the blue dragon shown along side the actual specimen collected aboard the Princess Alice in 1896 (Caption 4). Collecting notes from the expedition, kindly provided by Dr Nadia Ounais (Musee Oceanographique) describes observing them on 13 July in 1895. ““En 1895, 2 exemplaires typiques de cette espèce ont été pêchés le 13 juillet à la surface de la mer et la face ventrale d’un exemplaire a été figurée à l’état vivant avec ses couleurs (Pl.II, fig. II) et de grandeur naturelle…” which translates as “In 1895, 2 typical specimens of this species were caught on July 13 on the surface of the sea and the ventral side of a copy has been figured in the living state with its colors and of natural size…”
This juxtaposition of the brilliant blue watercolor and the actual diminutive, ¼-inch long, limp, bleached white preserved animal highlights the WHY underlying the work of the Blaschkas that has persisted the past 150 years; preserved specimens lacked vibrancy, colors and correct form, and though watercolors were both animated and aesthetically accurate, the meticulously rendered glass pieces brought the sensational forms and colors to life.
Amazingly enough, the discovery and naming of the Blue Dragon predates even these historic expeditions and dates back to the Forster Expeditions of 1772.
” Monday 14 Sept, 1772
This day we caught several dolphins, and a flying fish one foot long fell on the quarter- deck. ….. We had also at various intervals, found the sea covered with animals belonging to the class of mollusca, one of which, of a blue colour, in shape like a snail, with four arms, divided into many branches, was named Glaucus atlanticus; … ” (Forster, 1777: p. 49).
How could any of them know what was to become of the ocean’s 150 years later? They would all be stunned by the changes in ocean health and the global impacts of high carbon dioxide on ocean warming and ocean acidification.
Other historical work on Glaucus atlanticus.
- Bergh, S.R. (1884) Report on the Nudibranchiata dredged by H.M.S. Challengerduring the years 1873-1876. Report of the Scientific Results of the Voyage of H.M.S. Challenger during the years 1873-76, … Zoology, 10(26): 1- 154, pls. 1-14. [Glaucus: p.10-16]
- Forster, (1777) A voyage round the world in His Britannic Majesty’s sloop, Resolution, commanded by Capt. James Cook, during the years 1772, 3, 4, and 5 by George Forster. Vol 1: p49. (White, Robson, Elmsly & Robinson: London)
- Thompson,TE. & Bennett,I., Physalia nematocysts: Utilised by mollusks for defense. Science, 166: 1532-1533.
- Thompson,TE. & Bennett,I., Observations on Australian Glaucidae (Mollusca: Opisthobranchia). Zoological Journal of the Linnean Society, 49: 187-197.