Total confusion in California over mysterious blue creatures that have covered the state's beaches

Temperatures are beginning to ease and there are some brave souls who have already gone to enjoy the beach. In California, upon arriving at the sea, some bathers have noticed something quite strange. The shores have been filled with mysterious blue creatures, known as by-the-wind sailors.

The truth is that bathers are not used to seeing these species, but they are more common than you might think. Their presence on the shoreline is due to seasonal changes and ocean currents. Moving as a colony of hundreds of polyps, their presence has taken over almost all the seas of California. This species is known as Velella velella.

How do Velella velella reach the surface?

Although they look very similar to ordinary jellyfish, they are more closely related to the Portuguese man o' war family. They can grow up to 10 centimetres in length and move through the seas by wind power. Their feeding habits are also quite peculiar. Below the surface, they use small tentacles to capture small prey in the water.

Scientists believe that this number of sightings can only be related to the upwelling season. This is the way experts refer to the oceanographic phenomenon that moves cold water and nutrients from the depths of the ocean to the surface, causing species to also follow this path.

"The true start or end of that season changes each year based on a broad set of variables, but the presence of Velellas indicates a change in winds and currents, and the Velellas, driven by the current, head for the beaches,"explains Jennifer Stock, education specialist at the Greater Farallones National Marine Sanctuary