pteraeolidia

The curiosities of the Blue dragon nudibranch

Commonly referred to as the Blue dragon nudibranch, Pteraeolidia ianthina (Nudibranchia - Facelinidae), is a remarkable species of sea slug native to the Indo-Pacific region.

This is an extremely elongate species up to 5cm long, with large, curved arches of cerata (the projections on the upper surfaces of the body) along the length of the body. The cephalic tentacles have two distinctive dark purple (or blue) bands.

Although the body color of this nudibranch is translucent tan, the cerata, which are mostly blue or dark purple, lavender or golden brown, give the nudibranch most of its apparent color.

The Blue dragon nudibranch has many amazing survival strategies. When touched, the nudibranch will “flare” its cerata and the nematocysts will discharge on contact (it is one of the few nudibranchs with a sting strong enough to be felt by humans though usually not in areas with thicker skin such as the palm of the hand).

It is also able to autotomize (lose or detach) the posterior part of its body in order to distract, or free itself from, a potential predator. Later, the missing portion can be regenerated.

Another curiosity of this species is that the cerata contain zooxanthellae of the genus Symbiodinium that exhibit the capacity for photosynthesis, and they grow while reside in the sea slug. This symbiotic relationship with the algae helps the adult nudibranch to overcome a period of food shortage by getting photosynthetic products.

References: [1] - [2] - [3] - [4]

Photo credit: ©Sylke Rohrlach

Locality: New South Wales, Australia

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Pteraeolidia ianthina

…a strikingly marked species of of Facelinid nudibranch which is known to occur among shallow coral reefs throughout the Western Pacific Ocean, from Hawaii to the Philippines, to the waters of northeast Australia and parts of New Zealand. It is also known from the Red Sea. P. iathina is known to feed almost exclusively on hydroids, generally those which contain Symbiodinium spp. These dinoflagellates are “farmed” in the digestive diverticula of P. iathina allowing the sugars they photosynthesize to be used. 

Classification

Animalia-Mollusca-Gastropoda-Heterobranchia-Euthynerua-Nudipleura-Nudibranchia-Dexiarchia-Cladobranchia-Aeolidida-Aeolidioidea-Facelinidae-Pteraeolidia-P. ianthina 

Image: Richard Ling

A pair of Blue Dragon Nudibranchs | Pteraeolidia ianthina

“Pteraeolidia has evolved a method of capturing and farming microscopic plants (zooxanthellae) in its own body. The plants flourish in this protected environment and as they convert the sun’s energy into sugars, they pass a significant proportion on to the nudibranch for its own use. Adults can last some time without feeding, presumably obtaining sufficient nourishment from their zooxanthellae gardens.”   - 

(by Mick’s wet)

3

The sea dragon slug (Pteraeolidia ianthina): steals stinging cells and photosynthetic symbionts from its prey – while looking super fancy!

http://en.wikipedia.org/wiki/Pteraeolidia_ianthina

Pteraeolidia ianthina, one of the most common aeolids found, is often called a "blue dragon” by Eastern Australian divers because of its close resemblance to a Chinese dragon.[4] It is one of the most common aeolid nudibranchs found in Eastern Australia. It can inflict a painful sting to humans.

The slug is very elongated (7 cm) with many clusters of medium-large sized cerata along the length of the body. The fat rhinophores and the long cephalic tentacles have at least two dark purple bands that stand out. The tips of the cerata contain nematocysts.

Symbiotic zooxanthellae continue to photosynthesise inside the body and give rise to brown and green pigments. The zooxanthellae, together with the nematocysts, are presumed to be derived from coelenterate prey. These zooxanthellae occur within vacuoles in host cells derived from the endoderm.[5]

"This sea slug has evolved the ability to harness the sun’s energy for its own use. This is possible because the slug feeds on hydroids which contain symbiotic zooxanthellae, microscopic dinoflagellates that are photosynthetic — in other words that have the capability to make sugars from sunshine. The nudibranch farms these zooxanthellae within its own digestive diverticula. The zooxanthellae then convert the sun’s energy into sugars. The sugars are used by the slug.[7]

Image 1: Blue Dragon - Pteraeolidia ianthina

Tooth Brush Island. Flickr user billunder, 2009: http://www.flickriver.com/photos/12499727@N04/4230026282/

Image 2: Blue Dragon - Pteraeolidia ianthina

Flickr user billunder, Australia, 2009: http://www.flickriver.com/photos/12499727@N04/4232772648/

Blue Dragon - Pteraeolidia ianthina

Image 3: Sea dragon slug (Pteraeolidia ianthina), GBR, Australia

Photo by Arthur Anker: http://www.flickr.com/photos/artour_a/3385581613/in/set-72157623477677107

Pteraeolidia ianthina - Anilao, Philippines | ©Carlos Fernandez-Cid

Pteraeolidia ianthina, commonly known as the ‘Blue Dragon’, is one of a group of remarkable aeolid nudibranchs which are way ahead of man in harnessing solar energy.

This nudibranch has evolved a method of capturing and farming microscopic plants (zooxanthellae) in its own body. The plants flourish in this protected environment and as they convert the sun’s energy into sugars, they pass a significant proportion on to the nudibranch for its own use.

White animals are juveniles which as not yet developed their crop of zooxanthellae. If this species is similar to others that have been studied then they must obtain its first “injection” of zooxanthellae by feeding on a hydroid with symbiotic zooxanthellae. White juveniles are usually found in lush growths of short “turfing” hydroids, but until now no sign of zooxanthellae has been found in the hydroids.

Adults can last some time without feeding, presumably obtaining sufficient nourishment from their zooxanthellae gardens. The large solitary hydroid is the preferred adult food.

[Source and more information]

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On that topic, people often think that Goodra is partly based on this blue sea dragon sea slug, Glaucus atlanticus

but that looks nothing like Goodra

Understandably, It’s probably because the Glaucus atlanticus is really well known, i.e. it IS the dragon slug you first think of when you hear the words dragon + slug.

However, confusingly (and wonderfully)  there is another group of aeolid nudibranch sea slugs called blue dragons, the Pteraeolidia 

Which not only match Goodra’s colour scheme excellent but are called dragon sea slugs too!

Another closely related group also looks like our fave gooey dragon, the Phyllodesmium sp.

Anyway nudibranchs are SUPER COOL BRO

flickr

Dali moustache - Pteraeolidia ianthina - Blue dragon #marineexplorer by John Turnbull
Via Flickr:
Bare Island