Glaucus atlanticus

Taxobox
name = "Glaucus atlanticus"

---

image_width = 300px
image_caption = "Glaucus atlanticus" (left) and its close relative "Glaucilla marginata" (right)
regnum = Animalia
phylum = Mollusca
classis = Gastropoda
ordo = Opisthobranchia
subordo = Nudibranchia
superfamilia = Aeolidioidea
familia = Glaucidae
genus = "Glaucus"
species = "G. atlanticus"
binomial = "Glaucus atlanticus"
binomial_authority = Forster, 1777

"Glaucus atlanticus" (or Blue Glaucus) is a species of medium-sized, floating, blue sea slug, a pelagic aeolid nudibranch, a marine opisthobranch gastropod mollusk in the family Glaucidae. It is the only species in the genus "Glaucus", but is closely related to "Glaucilla marginata", another member of the family Glaucidae.

"G. atlanticus" has many common names, including: Blue sea slug, Blue ocean slug, Blue dragon and Sea lizard.

Description

This species typically grows to 6 cm in length. It is dark blue in color.

Distribution

This nudibranch is pelagic, and is distributed throughout the world's oceans, in temperate and tropical waters.

Habitat

This species floats upside down on the surface tension of the ocean water.

Life habits

"G. atlanticus" preys on other larger pelagic organisms: 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, as in many other nudibranchs, individual "Glaucus" will cannibalize each other if given the opportunity.

"G. atlanticus" is able to feed on "P. physalis" due to its immunity to the venomous nematocysts. The blue sea slug will consume the entire organism. After consumption it will select the most venomous nematocysts and [http://www.seaslugforum.net/factsheet.cfm?base=glauatla use them for defense] . "G. atlanticus" stores the venom in its cnidosacs, specialized sacs on the tip of their cerata, the thin feather-like "fingers" on its body. Because "Glaucus" stores the venom, it can produce a more powerful and deadly sting than the Man o' War upon which it feeds.

With the aid of a gas-filled sac located in its stomach, "G. atlanticus" is able to stay afloat at the surface. Due to the location of the gas sac the blue sea slug actually floats upside down. The dorsal surface, actually the foot and underside, has either a blue or blue-white coloration. The true dorsal surface is completely silver-grey. This coloration is an example of counter-shading, which helps protect "G. atlanticus" from predators from below,sides and above.

Scientists have often argued over whether "G. atlanticus" moves on its own or depends on the wind for locomotion.

"Glaucus" is, like most sea slugs, a hermaphrodite, meaning it contains both male and female reproductive organs. After mating, both slugs will produce egg strings.

External links

* [http://educatedearth.net/video.php?id=3029 Video of the Glaucus Atlanticus.]
* [http://www.seaslugforum.net/factsheet.cfm?base=glauatla Sea Slug Forum]
*cite journal |last=Valdés |first=Ágel |coauthors=Orso Angulo Campillo |year=2003 |month=November |title=Systematics of Pelagic Aeolid Nudibranchs Of The Family Glaucidae (Mollusca, Gastropoda) |journal= Bulletin of Marine Science |volume=75 |issue=3 |pages=381–389 |url=http://www.ingentaconnect.com/content/umrsmas/bullmar/2004/00000075/00000003/art00003 |accessdate= 2008-03-04
*eol|16852031