Meet the deeply fabulous Blue Glaucus, or Glaucus atlanticus... aka Blue Dragon, Sea Swallow, Blue Angel, Blue Sea Slug, Blue Ocean Slug and Lizard Nudibranch!
They are found in temperate and tropical ocean waters worldwide, specifically the Atlantic, Pacific, and Indian oceans!
Although they have been found east and south coasts of South Africa, in European waters, near Mozambique, and off Australia’s east coast.
It's beautiful colouring help them to camouflage with the ocean and sky!
Their body has a form of coloration known as countershading. The dorsal side (facing downward) is silvery grey, camouflaging it against the seas bright surface. While the ventral area (facing upwards) is dark and pale blue, and its head is covered with dark blue stripes, camouflaging against the seas blue colour!
They are voracious predators, their favoured prey is the Portuguese man o’ war. This looks like a jellyfish, but is actually a cnidarian and has numerous stinging cells (nematocysts) in its tentacles
Portuguese man o' war (Physalia physalis
Photo by Helene Hoffman
They transfer undigested nematocysts (stinging cells) from their prey to the cerata to use them to sting when hunting, or if it feels threatened!
Sexual reproduction could be problematic for a creature with a deadly sting....Fortunately, they have long, curved S-shape bends in their penises to avoid injury!
Also: you are usually seeing pictures of their bellies. This is because their bellies have that wonderful blue, while their backs are a more boring silver-grey, so their tummies are more photogenic.
They're colored this way because they live along the air-water surface tension... but from underneath, so they are always belly-up. The blue belly camouflages them from the air, and makes them look like water; their gray backs camouflage them from beneath, making them look like the air.
They live their lives upside-down, the air is their ground, and when they look "up" it's toward the ocean depths.
Such wonderful, fascinating creatures! Glaucus atlanticus is probably the most famous, and for a good reason: they look like beautiful little sea angels.
Sea angels that can kill you. Cute, little, blue, murder-angels!!
A lot of nudis seem to be cannibals, I don't know whether this is from preference or accidentally hoovering up the much smaller ones, probably worth investigating
Also the man o wars definitely need a post of their own, I love how some sea creatures look like individuals but are giant colonies... then again we have slime molds terrestrially and us humans, and we're a bit like a giant colony of bacteria wearing a person trench coat
I'm glad to have learned a bit about your favourite nudi, they're stunning creatures in every way (btw I have a special nudi post for Halloween, something fun and not very serious) 😀