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 take a close look at different Glaucus, as once you spot the difference they are easy to tell apart, even at a quick glance. Below is a photo with both of them so you can see easily the differences. What is showing is the underside of the creature, but this is what is seen from the top of the water.

Right: Glaucus atlanticus Left: Glaucilla bennettae

Most of Blue Fleet Welcomes Me Home is a journal post I have done about these.

Physalia physalis which we have been using to ID the blueblottles found here does not exist here. Those are an animal that grows to 30 cm, a near full crest, and a large number of tentacles that can extend to 50 m and I am sure we will all agree that we have not seen anything that large in all of our bluebottle obs.

So what do we call ours? Well there seems to be four possible ID's for our ones.

Physalia utriculus (top left) has a single main fishing tentacle, a float with a high crest in the middle half of the float and long, cylindrical, tapering, posterior extension (right hand side). They can also have a bloated float.

Crested Bluebottle - Physalia sp1 (full crest) (top right) has one single main fishing tentacle, and a prominent crest along the full length of the float which does not stand up high like the Physalia utriculus crest, instead it shows more as "joins" as seen in the sample photo.

Barrel Bluebottle Physalia sp2 (no crest) (bottom left) has a single main fishing tentacle and no crest. The float is also smooth without any "joins" but you must turn the float to make sure that the "join" was not sand down.

Irukanji Bluebottle - Physalia sp3 (multi-tentacled) (bottom right) which has multiple main fishing tentacles. These are the long ones and we can see in the photo that there are at least 2 long ones.

The crest is the main thing to look at as what it is will eliminate most of the other species. Next would be the number of main fishing lines although it is really obvious when there is more than one.

Further Reading
This Obs with lots of korero
Flag for Physalia Genus
Photographing Bluebottles
Bluebottle Guide - Coming Soon