Blue Dragon of sea
Kingdom:
Animalia
Phylum:
Mollusca
Class:
Gastropoda
Order:
Nudibranchia
Family:
Glaucidae
Super
family: Aeolidioidea
Genus:
Glaucus
Species
:G. atlanticus
Author:
(Forster, 1777)
The term Nudibranch is derived from two ancient
words namely - Nudus (naked) in Latin and
brankia (gillsGreek). They are shelless mollusc belonging to order
Nudibrachia . There are around 3000 species of nudibranchs are in the world. Glaucus atlanticus is one among them
belonging to the family Galucidae . They
are commonly termed as sea swallows, blue dragon, blue sea slugs based on its
floating capacity on pealgic water and appearance. Glaucus is the only genus with two species in the family Glaucidae
.They live in pelagic waters and are distributed in both tropical and temperate
regions all around the world . They
float upside down in the pelagic surface due to the location of air sac on the ventral side. Dorsal side of the
mollusc is silvery white or grey colour and ventral side is dark blue which
gives a counter shading property when the mollusc swims upside down. Average
size of this mollusc varies from 35mm to 43 mm.
It has a blunt head, elongated
and tapered body with 3 pairs of appendages . Finger like projections
rise from appendages called “cerata”. These creatures move in water by rowing
the cerata in the appendages and moving their body up and down. Glaucus are hermaphroditic in nature
(both male and female sex organs are present in the same animal). Egg strings
are produced and each egg is 60-75 mm wide and 75-97 mm long. Within 48-60
hours trochophore larva is formed, followed by veliger with larval shell after
3 days. These shelless molluscs contain shells during their veliger stage and
sheds it when it grows as adult. Like
other Nudibranchs, blue sea slugs are also carnivores feeding on a variety of
pelagic organisms including the
dangerous Portuguese Man O’ War, Physalia physalis; the ‘by-the-wind-sailor’Velella velella ; the
blue button, Porpita porpita ;
and the violet snail, Janthina
janthina . One peculiar character of this tiny creature is separation of
stinging cells (Nematocysts) of hydroids in digestive system after feeding. It
stores the nematocysts in minute sac like structure called “cnidosacs” present
in the tip of each cerata and uses for defence and predation. Since, it stores
more nematocysts it can cause more damage than the hydroids.
Acknowledgements
:
Pictures were collected from following links
Pictures were collected from following links
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