Thousands of bright blue sea creatures, which look like a little jellyfish and are known as velella velellas, are getting washed ashore on beaches and lakes across the West Coast in the US.

The invertebrates are known as by-the-wind sailors because part of their body look likes a sail sticking above the water. The eye-catching color has increased the interest of beachgoers.

Vicky Waters, Deputy Director for Public Affairs with California State Parks, said that these numbers have been sufficient over the past various weeks to get people's attention.

According to Doctor Kevin Raskoff, biology professor at Biology Department at Monterey Peninsula College, the appearance of the velella group is somewhat repetitive. Usually these creatures live in a big group far from the shore.

"The numbers, if you extrapolate, are awe inspiring. With some of my students we counted more than a thousand per meter. The numbers get astronomical pretty fast", Kevin Raskoff told Southern California Public Radio.

These were first seen in Northern California last month. According to researchers, they feed on zooplankton and fish, and their natural predators are snails.

Raskoff said that images from beaches in San Pedro, California, and La Push, Washington, demonstrate the number of jellyfish carcasses splayed out on the sand. There is not an instant need for safety because their stingers are weak to stab skin of human.

Jellyfish swim on their own using their bell-shaped top as a propeller. If the ocean current and winds are strong then it can push the jellyfish together which will cause an apparent bloom, according to the magazine reports.

The tiny round creatures are dying on beaches in California, Oregon, Washington and even the UK, according to scientists.