Unusual blue sea swallow spotted on Cape beach

Posted by Anita Froneman on 18 November 2020

The ocean is home to a myriad weird and wonderful creatures, many of whom we don’t often get a glimpse at. Cape Town resident Maria Wagener captured a special sighting of a blue sea swallow that washed up on Fish Hoek beach.

The blue sea slug (Glaucus atlanticus) is a species of small shell-less gastropod mollusc. These animals are pelagic, meaning they float upside down by using the surface tension of the water to stay up, where they are carried along by the winds and ocean currents.

Also sometimes called blue dragons or blue angels, these tiny slugs are only about 3cm in length. Interestingly, they are not poisonous themselves but can store the poison of their prey and release them at a later time as a defence mechanism.

According to Oceana, they retain the toxins or stinging cells of other creatures they consume like bluebottles in their own skin, with which they can then deliver painful stings when threatened or stressed.

Fact: A group of blue glaucuses floating together is called a ‘blue fleet’!

Take a look at these fascinating pictures:


It seems blue is the colour of the day as Wagener also spotted a Columbus’ crab (Planes minutus);

as well as what appears to be a violet sea snail.

Pictures: Fish Hoek Beach/Maria Wagener

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