Distinguishing Glaucus atlanticus and Glaucilla bennettae

There are two species of Glaucus / Glaucilla that wash up on our shores and in some ways they are the stars of the blue fleet as they are not seen as much as the other members.

These float upside down, so what is visable when looking down into the water is actually the underside, while what is seen from being in the water looking up - usually just white / blue without the colour variations - is actually the dorsal, or top.

The sea swallow - Glaucus atlanticus can be identified by the two dark stripes with a silver strip inside them visable when they are floating in to water - this is the foot. G.atlanticus is larger, up to about 30mm, and also has a longer tail.

Glaucilla bennettae (old name Glaucus bennettae) has two dark stripes that are have a blue strip inside them, instead of silver . G.bennettae is smaller - about 12-15mm and the tail blends in with the "frilly bits". This species tends to have a "glitter look".

If you ever come across a washup ...more ↓

Posted on February 08, 2019 02:50 AM by tangatawhenua tangatawhenua | 0 comments | Leave a comment
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We know that the whole of the blue fleet landed in NZ Feb 2016 so this project is for recording other Blue Fleet critter sightings so we can monitor when the whole fleet lands again.

Mini tangatawhenua created this project on October 08, 2017

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