Glaucus atlanticus

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Glaucus atlanticus
Glaucus atlanticus 1 cropped.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Nudibranchia
Suborder: Cladobranchia
Family: Glaucidae
Genus: Glaucus
Species:
G. atlanticus
Binomial name
Glaucus atlanticus
Forster, 1777
Synonyms [1]
  • Doris radiataGmelin, 1791 (synonym)
  • Glaucus distichoicusd'Orbigny, 1837
  • Glaucus flagellumBlumenblach, 1803 (synonym)
  • Glaucus hexapterigiusCuvier, 1805 (synonym)
  • Glaucus lineatusReinhardt & Bergh, 1864
  • Glaucus longicirrhusReinhardt & Bergh, 1864

Glaucus atlanticus (common names include the blue sea dragon, sea swallow, blue angel, blue glaucus, dragon slug, blue dragon, blue sea slug, and blue ocean slug) is a species of sea slug in the family Glaucidae. [2]

Contents

These sea slugs live in the pelagic zone (open ocean), where they float upside-down by using the surface tension of the water to stay afloat. They are carried along by the winds and ocean currents. G. atlanticus makes use of countershading; the blue side of their bodies faces upwards, blending in with the blue of the water. The silver/grey side of the sea slug faces downwards, blending in with the sunlight reflecting on the ocean's surface when viewed from below the surface of the water.

G. atlanticus feeds on other pelagic creatures, including the Portuguese man o' war and other venomous siphonophores. This sea slug stores stinging nematocysts from the siphonophores within its own tissues as defence against predators. Humans handling the slug may receive a very painful and potentially dangerous sting.

Taxonomy

This species looks similar to, and is closely related to, G. marginatus , which is now understood to be not one species, but a cryptic species complex of four separate species that live in the Indian and Pacific Oceans. [1] [3] It shares the common name "blue dragon" with Pteraeolidia ianthina [4] and G. marginatus. [5]

Description

At maturity, G. atlanticus is usually around 3 cm (1.2 in) in length, [6] though larger specimens have been found. [7] It can live up to a year under the right conditions. [8] It is silvery grey on its dorsal side and dark and pale blue ventrally. It has dark blue stripes on its head. It has a flat, tapering body and six appendages that branch out into rayed, finger-like cerata. [9]

Cerata, also known as papillae, extend laterally from three different pairs of peduncles. The papillae are placed in a single row (uniseriate) and may number up to 84 in total. [10]

G. atlanticus is usually found in tropical/subtropical areas, floating at the ocean's surface due to the stored gulped air inside its stomach. It usually feeds on cnidarians, which can be noisy due to air escaping its stomach as it feeds. [11] [12] [13]

The radula of this species bears serrated teeth, [14] which paired with a strong jaw and denticles, allows it to grasp and "chip down" parts of its prey. [8]

Buoyancy and coloration

With the aid of a gas-filled sac in its stomach, G. atlanticus floats at the surface. Due to the location of the gas sac, this species floats upside down. The upper surface is actually the foot (the underside in other slugs and snails), and this has either a blue or blue-white coloration. The true dorsal surface (carried downwards in G. atlanticus) is completely silver-grey. This coloration is an example of countershading, which helps protect it from predators that might attack from below and from above. [15] The blue coloration is also thought to reflect harmful ultraviolet sunlight.

Distribution and habitat

Glaucus atlanticus is the blue sea slug shown here out of water on a beach, and thus collapsed; however, touching the animal directly with your skin can result in a painful sting, with symptoms similar to those caused by the Portuguese man o' war Glaucus atlant..jpg
Glaucus atlanticus is the blue sea slug shown here out of water on a beach, and thus collapsed; however, touching the animal directly with your skin can result in a painful sting, with symptoms similar to those caused by the Portuguese man o' war
The slug in the water Blue dragon-glaucus atlanticus (8599051974).jpg
The slug in the water

This nudibranch is pelagic, and some evidence indicates that it occurs throughout the world's oceans, in temperate and tropical waters. It has been recorded from the east and south coasts of South Africa, European waters, the east coast of Australia, and Mozambique. [3] Observations in 2015 and 2016 suggested that the G. atlanticus species' geographical range had increased northward by 150 km in the Gulf of California compared with previous sightings. [16]

Since the middle of the 19th century, records of this species have been reported on the Azores. [7]

G. atlanticus was recently found in the Humboldt Current ecosystem in Peru in 2013, and off Andhra Pradesh in India in 2012. This is in line with the known habitat characteristics of the species; they thrive in warm, temperate climates in the Southern Pacific, and in circumtropical and Lusitanian environments. Before finding G. atlanticus off Andhra Pradesh, these nudibranchs were documented as having been seen in the Bay of Bengal and off the coast of Tamil Nadu, India, over 677 km apart. [17] G. atlanticus was also recently found off Bermuda in January 2016, [18] and uncommonly washes ashore on east coast beaches at Barbados, Lesser Antilles.

Although these sea slugs live on the open ocean, they sometimes accidentally wash up onto the shore, so they may be found on beaches. [10] In April 2022, specimens were found in the Gulf of Mexico along the Texas coast. [19] On August 31, 2023, blue sea slugs were reported to be found along Karon Beach, Phuket, Thailand. [20] [21]

Life history and behavior

G. atlanticus preys on other larger pelagic organisms. The sea slugs can move toward prey or mates by using their cerata, the thin feather-like "fingers" on its body, to make slow swimming movements. [10] [22] They are known to prey on the dangerously venomous Portuguese man o' war ( Physalia physalis ), the by-the-wind-sailor ( Velella velella ), the blue button ( Porpita porpita ), and the violet snail, Janthina janthina . Occasionally, individuals attack and eat other individuals in captivity.

The species is able to feed on the Portuguese man o' war due to its immunity to the venomous nematocysts. The slug consumes chunks of the organism and appears to select and store the most venomous nematocysts for its own use against future prey. [23] The nematocysts are collected in specialized sacs (cnidosacs) at the tip of the animal's cerata. Because G. atlanticus concentrates the venom, it can produce a more powerful and deadly sting than the man o' war on which it feeds. [24]

Like almost all heterobranchs, blue dragons are hermaphrodites and their male reproductive organs have evolved to be especially large and hooked to avoid their partner's venomous cerata. [8] Unlike most nudibranchs, which mate with their right sides facing, sea swallows mate with ventral sides facing. [25] After mating, both individuals are able to lay eggs and can release up to 20 on an egg string, often laying them in wood pieces or carcasses. [8] On average, G. atlanticus can lay 55 egg strings per hour. [12] G. atlanticus is not globally panmictic, but is localized within ocean basins. Gene flow among Afro-Eurasian and American populations is thus hindered by physical obstructions and water temperatures in the Arctic and Southern Oceans. [11]

Sting

G. atlanticus can swallow the venomous nematocysts from siphonophores, such as the Portuguese man o' war, and store them in the extremities of its finger-like cerata. [24] Picking up the animal can result in a painful sting, with symptoms similar to those caused by the Portuguese man o' war. [26] The symptoms that may appear after being stung are nausea, pain, vomiting, acute allergic contact dermatitis, erythema, urticarial papules, potential vesicle formation and postinflammatory hyperpigmentation. [13]

In 2023, Julian Obayd, a TikTok user whose videos focus on marine life, went viral after going to the hospital for several Blue Dragon stings. In the viral video, Obayd claimed he had been stung when moving a group of Blue Dragons drying out in the sand and warned viewers about the risk of being stung. [27]

Related Research Articles

<span class="mw-page-title-main">Portuguese man o' war</span> Marine invertebrate

The Portuguese man o' war, also known as the man-of-war or bluebottle, is a marine hydrozoan found in the Atlantic Ocean and the Indian Ocean. It is considered to be the same species as the Pacific man o' war or bluebottle, which is found mainly in the Pacific Ocean. The Portuguese man o' war is the only species in the genus Physalia, which in turn is the only genus in the family Physaliidae.

<span class="mw-page-title-main">Nudibranch</span> Order of gastropods

Nudibranchs belong to the order Nudibranchia, a group of soft-bodied marine gastropod molluscs that shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to match, such as "clown", "marigold", "splendid", "dancer", "dragon", and "sea rabbit". Currently, about 3,000 valid species of nudibranchs are known.

<span class="mw-page-title-main">Sea slug</span> Group of marine gastropods

Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails that, over evolutionary time, have either entirely lost their shells or have seemingly lost their shells due to having a significantly reduced or internal shell. The name "sea slug" is often applied to nudibranchs and a paraphyletic set of other marine gastropods without apparent shells.

<span class="mw-page-title-main">Siphonophorae</span> Order of colonial hydrozoans with differentiated zooids

Siphonophorae is an order within Hydrozoa, which is a class of marine organisms within the phylum Cnidaria. According to the World Register of Marine Species, the order contains 175 species described thus far.

<i>Physalia</i> Genus of hydrozoans

Physalia is a genus of the order Siphonophorae, colonies of four specialized polyps and medusoids that drift on the surface of the Atlantic, Indian and Pacific oceans. Although these organisms look like a single multicellular organism, each specimen is actually a colony of minute organisms called zooids that have to work together for survival. A gas-filled bladder resembling a blue bottle provides buoyancy, and long tentacles of venomous cnidocytes provide a means of capturing prey. A sail on the float, which may be left or right-handed, propels Physalia about the sea, often in groups. These siphonophores sometimes become stranded on beaches, where their toxic nematocysts can remain potent for weeks or months in moist conditions. Both species of this siphonophore resemble a jellyfish in appearance, with their gas-filled float and cluster of polyps beneath, which can hang up to 30 or 165 ft below the surface of the sea.

<i>Velella</i> Species of cnidarian

Velella is a monospecific genus of hydrozoa in the Porpitidae family. Its only known species is Velella velella, a cosmopolitan free-floating hydrozoan that lives on the surface of the open ocean. It is commonly known by the names sea raft, by-the-wind sailor, purple sail, little sail, or simply Velella.

<i>Glaucus marginatus</i> Species of gastropod

Glaucus marginatus is a species of small, floating, blue sea slug; a pelagic (open-ocean) aeolid nudibranch; a marine opisthobranch gastropod mollusc in the family Glaucidae. This species is closely related to Glaucus atlanticus, and is part of a species complex along with Glaucus bennettae, Glaucus thompsoni, and Glaucus mcfarlanei. Like Glaucus atlanticus, it is commonly known as a blue dragon.

<span class="mw-page-title-main">Cerata</span> Anatomical structures found in nudibranch sea slugs

Cerata, singular ceras, are anatomical structures found externally in nudibranch sea slugs, especially in aeolid nudibranchs, marine opisthobranch gastropod mollusks in the clade Aeolidida. The word ceras comes from the Greek word "κέρας", meaning "horn", a reference to the shape of these structures.

<i>Fiona pinnata</i> Species of gastropod

Fiona pinnata, common name Fiona, is a species of small pelagic nudibranch, a marine gastropod mollusk in the superfamily Fionoidea. This nudibranch species lives worldwide on floating objects on seas, and feeds mainly on barnacles, specifically goose barnacles in the genus Lepas.

<i>Aeolidia papillosa</i> Species of gastropod

Aeolidia papillosa, known as the common grey sea slug, is a species of nudibranch in the family Aeolidiidae.

<i>Janthina janthina</i> Species of gastropod

Janthina janthina is a species of holoplanktonic sea snail, a marine gastropod mollusk in the family Epitoniidae. Its common names include violet sea-snail, common violet snail, large violet snail and purple storm snail.

<i>Porpita porpita</i> Species of hydrozoan

Porpita porpita, or the blue button, is a marine organism consisting of a colony of hydroids found in the warmer, tropical and sub-tropical waters of the Pacific, Atlantic, and Indian oceans, as well as the Mediterranean Sea and eastern Arabian Sea. It was first identified by Carl Linnaeus in 1758, under the basionym Medusa porpita. In addition, it is one of the two genera under the suborder Chondrophora, which is a group of cnidarians that also includes Velella. The chondrophores are similar to the better-known siphonophores, which includes the Portuguese man o' war, or Physalia physalis. Although it is superficially similar to a jellyfish, each apparent individual is actually a colony of hydrozoan polyps. The taxonomic class, Hydrozoa, falls under the phylum Cnidaria, which includes anemones, corals, and jellyfish, which explains their similar appearances.

<i>Paraflabellina funeka</i> Species of gastropod

The purple lady nudibranch, Paraflabellina funeka, is a species of aeolid nudibranch, and is a very colourful sea slug. It is a marine gastropod mollusc in the family Flabellinidae.

<i>Phyllodesmium</i> Genus of gastropods

Phyllodesmium is a genus of predatory sea slugs, aeolid nudibranchs, marine gastropod molluscs in the family Myrrhinidae.

<i>Glaucus</i> (gastropod) Genus of gastropods

Glaucus is a genus of small blue pelagic sea slugs. They are aeolid nudibranchs, ranging in size from 20 to 40 mm. They feed on colonial cnidarians such as Portuguese man o' wars, blue buttons, and purple sails. They can produce painful and potentially dangerous stings when handled, as they store the venomous nematocysts of their prey. Glaucus is the only genus in the family Glaucidae. It includes five species.

<i>Pteraeolidia ianthina</i> Species of gastropod

Pteraeolidia ianthina is a sea slug, an aeolid nudibranch in the family Facelinidae. It is known as a blue dragon, a name it shares with Glaucus atlanticus and Glaucus marginatus.

<i>Janthina globosa</i> Species of gastropod

Janthina globosa is a species of holoplanktonic sea snail, a marine gastropod mollusk in the family Epitoniidae, the violet snails or purple storm snails.

<i>Coryphella verrucosa</i> Species of gastropod

Coryphella verrucosa, is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusc in the family Coryphellidae.

<span class="mw-page-title-main">Cnidosac</span>

A cnidosac is an anatomical feature that is found in the group of sea slugs known as aeolid nudibranchs, a clade of marine opisthobranch gastropod molluscs. A cnidosac contains cnidocytes, stinging cells that are also known as cnidoblasts or nematocysts. These stinging cells are not made by the nudibranch, but by the species that it feeds upon. However, once the nudibranch is armed with these stinging cells, they are used in its own defense.

<span class="mw-page-title-main">Ocean surface ecosystem</span>

Organisms that live freely at the ocean surface, termed neuston, include keystone organisms like the golden seaweed Sargassum that makes up the Sargasso Sea, floating barnacles, marine snails, nudibranchs, and cnidarians. Many ecologically and economically important fish species live as or rely upon neuston. Species at the surface are not distributed uniformly; the ocean's surface provides habitat for unique neustonic communities and ecoregions found at only certain latitudes and only in specific ocean basins. But the surface is also on the front line of climate change and pollution. Life on the ocean's surface connects worlds. From shallow waters to the deep sea, the open ocean to rivers and lakes, numerous terrestrial and marine species depend on the surface ecosystem and the organisms found there.

References

  1. 1 2 "Glaucus". WoRMS. World Register of Marine Species . Retrieved 5 August 2012.
  2. ↑ Lalli, C. M.; Gilmer, R. W. (1989). Pelagic snails: the biology of holoplanktonic gastropod mollusks. Stanford University Press. p. 224. ISBN   978-0-8047-1490-7.
  3. 1 2 Churchill, Celia K. C.; Valdés, Ángel; ó Foighil, Diarmaid (2014). "Molecular and morphological systematics of neustonic nudibranchs (Mollusca: Gastropoda: Glaucidae: Glaucus), with descriptions of three new cryptic species". Invertebrate Systematics. 28 (2): 174. doi:10.1071/IS13038. S2CID   84010907.
  4. ↑ Rudman, W. B. (15 July 2010). "Pteraeolidia ianthina (Angas,1864)". The Sea Slug Forum. Australian Museum . Retrieved 13 February 2021.
  5. ↑ Salleh, Anna (12 February 2021). "Bizarre 'blue fleet' blows onto Australia's east coast". ABC News. Australian Broadcasting Corporation . Retrieved 13 February 2021.
  6. ↑ "Glaucus atlanticus (blue sea slug)". The Natural History Museum. Archived from the original on 27 June 2015. Retrieved 13 April 2013.
  7. 1 2 "Dragão Azul do Mar". RTP. Archived from the original on 17 November 2021. Retrieved 14 November 2020.
  8. 1 2 3 4 "Blue Dragons of the Sea". Smithsonian Museum of Natural History . Retrieved 14 November 2020.
  9. ↑ Piper, R. (2007). Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals. Greenwood Publishing Group. pp.  42–43. ISBN   978-0-313-33922-6.
  10. 1 2 3 Srinivasulu, Bhargavi; Srinivasulu, C.; Kumar, G. Chethan (2012). "First record of the blue sea slug (Glaucus atlanticus) from Andhra Pradesh–India". Taprobanica: The Journal of Asian Biodiversity. 4 (1): 52–53. doi: 10.4038/tapro.v4i1.4386 .
  11. 1 2 Churchill, Celia K. C.; Valdés, Ángel; Ó Foighil, Diarmaid (1 April 2014). "Afro-Eurasia and the Americas present barriers to gene flow for the cosmopolitan neustonic nudibranch Glaucus atlanticus". Marine Biology. 161 (4): 899–910. Bibcode:2014MarBi.161..899C. doi:10.1007/s00227-014-2389-7. S2CID   84153330.
  12. 1 2 Helm, Rebecca R. (14 December 2021). "Natural history of neustonic animals in the Sargasso Sea: reproduction, predation, and behavior of Glaucus atlanticus, Velella velella, and Janthina spp". Marine Biodiversity. 51 (6): 99. Bibcode:2021MarBd..51...99H. doi: 10.1007/s12526-021-01233-5 . S2CID   245186096.
  13. 1 2 Pinotti, Raphael M.; Bom, Fabio C.; Muxagata, Erik (8 April 2019). "On the occurrence and ecology of Glaucus atlanticus Forster, 1777 (Mollusca: Nudibranchia) along the Southwestern Atlantic coast". Anais da Academia Brasileira de Ciências. 91 (1): e20180154. doi: 10.1590/0001-3765201920180154 . PMID   30994760. S2CID   119501907.
  14. ↑ Thompson, T. E.; McFarlane, I. D. (2008). "Observations on a collection of Glaucus from the Gulf of Aden with a critical review of published records of Glaucidae (Gastropoda, Opisthobranchia)". Proceedings of the Linnean Society of London. 178 (2): 107–123. doi:10.1111/j.1095-8312.1967.tb00967.x.
  15. ↑ "Habitat – Glaucus Atlanticus". Bluedragonslug.weebly.com. Retrieved 14 March 2018.
  16. ↑ Hernández, Luis; Munguía-Vega, Adrián; Pérez-Alarcón, Fernanda; Fernández-Rivera-Melo, Francisco J.; Angulo-Campillo, Orso (2018). "Occurrence of Glaucus atlanticus in the Midriff Islands Region, Gulf of California, Mexico". American Malacological Bulletin. 36: 145–149. doi:10.4003/006.036.0113. S2CID   89794645.
  17. ↑ Uribe, Roberto A.; Nakamura, Katia; Indacochea, Aldo; Pacheco, Aldo S.; Hooker, Yuri; Schrödl, Michael (September 2013). "A review on the diversity and distribution of opisthobranch gastropods from Peru, with the addition of three new records". Spixiana. 36 (341–8391): 43–60. Retrieved 24 October 2014.
  18. ↑ Johnston-Barnes, Owain (25 January 2016). "Diver finds 'blue dragons' at Spittal Pond". The Royal Gazette.
  19. ↑ Patton, Mary Claire (11 April 2022). "Don't Touch: Rare blue dragons are showing up on Texas beaches again". KSAT 12.
  20. ↑ "Venomous 'blue dragon' found on Phuket beach". Bangkok Post. Retrieved 1 September 2023.
  21. ↑ Petpailin, Petch (31 August 2023). "Beach warning: Venomous blue dragon sea slug spotted in Phuket". Thaiger. Retrieved 1 September 2023.
  22. ↑ MacLellan, Amelia "Glaucus atlanticus (blue sea slug)". The Natural History Museum. Retrieved 2013-04-13
  23. ↑ Asmelash, Leah (9 May 2020). "Rare blue dragons are washing up on the Padre Island National Seashore". CNN. Retrieved 11 May 2020.
  24. 1 2 Rudman, W. B. (6 November 1998). "Glaucus atlanticus Forster, 1777". Sea Slug Forum. Retrieved 26 February 2011.
  25. ↑ Debelius, H.; Kuiter, R. H. (2007). Nudibranchs of the world. IKAN-Unterwasserarchiv. ISBN   978-3-939767-06-0.
  26. ↑ Ottuso, Patrick Thomas (May 2009). "Aquatic antagonists: Indirect nematocyst envenomation and acute allergic contact dermatitis due to nudibranchs" (PDF). Cutis. Vol. 83. Archived from the original (PDF) on 23 July 2021. Retrieved 27 April 2015.
  27. ↑ Dahlstrom, Michael (10 February 2023). "Man's warning after 'incredibly dangerous' stunt at Aussie beach goes viral". Yahoo! News Australia.

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