Drifting through the icy waters of the Arctic Ocean, there is an angelic creature to be found.
A sea angel, a form of pteropod that will spend its entire life
swimming in the frigid seas without ever touching the bottom.
With its translucent fragile body and graceful wings, it's easy to see where it got its name.
Occasionally, their graceful mating dance can be seen,
which can last up to four hours as the pair drift together, connected to one another.
And when more of them gather, they become known as a Chorus of Sea Angels.
What's interesting is that neither one is really male or female, they are protandrous
hermaphrodites, meaning they are both male and female at different stages of their life cycles.
Despite their name and ghostly appearance, sea angels are a variety of shell-less sea snails
that slowly beat their adapted wing-like parapodia to get around in the water column.
And they are predators - feeding on fellow pteropods and sea butterflies.
This tiny pteropod variety builds a gigantic net structure made of mucus around itself,
in order to capture particles of another festive feature of the deep sea. Marine snow.
Yes, it snows in the deep sea too, but all-year-round as it has done uninterrupted
for thousands of years. Though here, it is in the form of a constant stream of organic matter,
including tiny particles of faeces, dead animals,
silt, and sand. You might want to think twice before attempting to catch these
snowflakes on your tongue - but for many inhabitants of the deep sea, it is their
only option. This snowfall of particles is energy-rich, and the deep sea relies almost
entirely on this phenomenon to bring nutrients down from the more productive shallower waters.
This is because the lack of sunlight in the depths makes photosynthesis
impossible - so nutrient production is confined to rare hydrothermal vents,
brine pools, and whale-fall ecosystems, where chemosynthetic bacteria produce energy for life.
Some organisms will go to extraordinary lengths to get their share of this
festive feast. The diet of the vampire squid consists largely of marine snow. They can be
seen filtering the particles out of the water - with their specially adapted filamentous tentacles
extending into the snowfall, to gather debris and bring it back to their mouths.
In the dark of the deep sea, their bioluminescent tentacles shine like
Christmas lights, as do many other deep sea creatures, like the firefly squid.
This phenomenon results from chemical reactions within the organisms.
Much marine bioluminescence found down here is expressed in the blue-green part
of the visible light spectrum - colours that are most visible in the deep sea.
Returning to the shallows, tropical reefs are also dressed up for Christmas.
Adorning colourful corals, we find a forest of Christmas tree worms, a form of polychaete worm,
each with two brightly coloured crowns that emerge from a tube-like body. The fir tree-like
hairs that radiate from the tubes are appendages used for catching plankton floating in the water.
So there you have it. A few festive reminders from the ocean,
a wondrous but delicate ecosystem. If we aren't careful, we may lose them forever.
Merry Christmas, and a happy new year from natural world facts. See you soon.