GOD MADE THEM ALL: THE BLUE GLAUCUS

 

THE GLAUCUS ATLANTICUS

Glaucus atlanticus, commonly called the blue sea dragon, sea swallow, blue angel, blue glaucus, dragon slug, blue dragon, blue sea slug or blue ocean slug,  is a species of small, blue sea slug, a pelagic (open-ocean) aeolid nudibranch, a shell-less gastropod mollusk in the family Glaucidae.

These sea slugs are pelagic; they float upside down by using the surface tension of the water to stay up, where they are carried along by the winds and ocean currents. The Glaucus Atlanticus makes use of countershading. The blue side of their body faces upwards, blending in with the blue of the water. The silver/grey side of the sea slugs faces downwards, blending in with the sunlight reflecting on the ocean's surface when viewed facing upwards underwater.

Glaucus 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.

 

At maturity G. atlanticus can be up to 3 cm (1.2 in) in length, though larger specimens have been found. It can live up to a year under the right conditions. 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. Cerata, also known as papillae, extend laterally from three different pairs of peduncles. The papillae are placed in a single row and may be up to 84 inches total.

Glaucus atlanticus is usually found in tropical/subtropical areas, floating at the ocean's surface due to the stored gulped air inside their stomachs. They usually feed on cnidarians, which can be noisy due to air escaping their stomachs as they feed.

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

 

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 snail), and this has either a blue or blue-white coloration. The true dorsal surface 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. The blue coloration is also thought to be harmful.

 

This nudibranch is pelagic, and there is some evidence 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. Since the middle of the 19th century, records of this species have been reported on the Azores.

Glaucus atlanticus was 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 kilometers apart.

Glaucus atlanticus was also recently found off Bermuda in January 2016, 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, and therefore they may be found on beaches. In April 2022, specimens were found in the Gulf of Mexico along the Texas coast. 

 

Glaucus atlanticus is able to swallow the venomous nematocysts from siphonophores such as the Portuguese man o' war, and store them in the extremities of its finger-like cerata. Picking up the animal can result in a painful sting, with symptoms similar to those caused by the Portuguese man o' war. 

The symptoms that may appear after being stung are nausea, pain, vomiting, acute allergic contact dermatitis, erythema, urticarial papules, potential vesicle formation and post-inflammatory hyperpigmentation.