Girish Mahajan (Editor)

Janthina janthina

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Kingdom
  
Family
  
Janthinidae

Scientific name
  
Janthina janthina

Higher classification
  
Janthina

Superfamily
  
Genus
  
Janthina

Phylum
  
Rank
  
Species

Janthina janthina PROSOBRANCHIA Janthina janthina

Similar
  
Janthina, Janthinidae, Porpita porpita, Velella, Glaucus

Janthina janthina, common name the violet sea-snail or common violet snail, is a species of holoplanktonic sea snail, a marine gastropod mollusk in the family Janthinidae, the violet snails or purple storm snails.

Contents

Janthina janthina Janthina janthina violet snail

Distribution

Janthina janthina Pictures How BubbleRafting Snails Evolved

This species is found worldwide in the warm waters of tropical and temperate seas, floating at the surface. They are often found in large groups and sometimes become stranded on beaches when they are blown ashore by strong winds.

Janthina janthina httpsuploadwikimediaorgwikipediacommonsthu

These snails are a unique part of the pleuston, organisms living on or at the very surface of the water, because of their relatively large size. They have veliger or free swimming larvae, but the adults do not swim and cannot create their rafts except at the surface where air bubbles are available.

Habitat

Janthina janthina Janthina Janthina exigua

These snails are pelagic, drifting on the surface of the ocean, where they feed upon pelagic hydrozoans, especially the by-the-wind sailor Velella velella and the Portuguese man o' war Physalia physalis.

Description

Janthina janthina is a member of the Janthinidae family, snails that trap air bubbles with a layer of clear chitin to maintain their positions at the surface of the ocean where they are predatious on the hydrozoans. In addition to the bubble raft, only the veliger, or larval stage, has an operculum, and the shell is paper-thin to allow the animal to float upside down at the surface.

The snail's shell is reverse countershaded, because of its upside-down position in the water column. There is a light purple shade on the spire of the shell, and a darker purple on the ventral side. The animal has a large head on a very flexible neck. The eyes are small and are situated at the base of its tentacles.

The snail begins life as a male and later changes to the female of the species. The eggs are held by the female until they develop into a larval form.

The shell is almost smooth with a slightly depressed-globose shape. It is thin and delicate, and is without an operculum. The colour of the shell is violet, with a paler upper surface. The height of the species shell is up to 38 mm, the width to 40 mm.

References

Janthina janthina Wikipedia