How did you do with April’s mystery creature? It was a bit deceptive because it looked like a jellyfish but it is not actually one… it is the Velella velella and here are five facts all about it!
Image credit: Wilson44691 - Own work, CC0
So good they named it twice
The Velella velella is the only known species in its genus, therefore it is often referred to as just velella. It goes by other names too, the most common one is ‘by the wind sailor’ but it is sometimes also called the ‘purple sail’ or ‘little sail’. I think we can agree that sailing is a common theme here! And it is no wonder, it looks quite like a mini sail boat. It is deep blue/purple in colour with a translucent stiff, ridged sail along the mid line.
Looks like a jellyfish but…
It is not a jellyfish – it is actually a hydroid colony; it is made up of hundreds of small organisms, each with their own different function. Each colony is considered all male or all female. They are only about 7cm in diameter.
At the mercy of the winds
There is no way for the velella to propel itself around in the open oceans in which it is found. Instead it is at the mercy of the winds, moving in whatever direction the prevailing wind takes it. This is why, under certain weather conditions, large numbers of these are washed ashore, particularly after stormy conditions and high winds.
Image credit: Dan from United Kingdom - Flickr.com - image description page, CC BY 2.0, Link
Valella can be found all over the world but mostly in tropical or subtropical waters. They are pleuston – organisms that live partly in and partly above water.
Eat or be eaten
Velella are typically eaten by specialized gastropods (mollusks) such as certain nudibranches. They are carnivorous themselves, feeding on plankton. The short tentacles that reach into the water contain toxins to stun their prey.
Although that are not considered a threat to humans, these toxins could possibly cause some mild skin or eye irritation, if handled.
Division of labour
The various life forms that make up the colony have specialised functions; some are involved in defence, some feeding, others reproduction etc. Any nutrients ingested from feeding are distributed among all the life forms of the colony.
Reproduction is by asexual budding (meaning that tiny new organisms , called medusa, are formed from little nodes that bud from the adult; these buds grown and eventually break away. This process of reproduction can produce thousands of these tiny medusa, each only 1mm in diameter.
Check back tomorrow for another mystery creature for you to solve!