By-the-wind Sailor

By-the-wind Sailor by Vikki Muldowney


Scientific name: Velella vellela
These mysterious and beautiful creatures rely on warm ocean currents to ‘sail’ them around the world... not a bad life?

Species information


Oval float up to 10 cm in length but usually smaller

Conservation status

Commonly found floating on the surface of the warmer waters of the world’s oceans, but very little is known about their lives.

When to see

September to March


This incredibly strange and beautiful species is known as a colonial hydroid. They are similar to the Portuguese man o war as they are made up of a colony of tiny individual animals. They are not true jellyfish.

Its characteristic sail gives the animal its name, 'by-the-wind-sailor'. The sail allows the organism to catch the wind and travel on ocean currents, using its stinging tentacles to prey on young fish and other small animals while it travels. They are at the mercy of the winds and so are usually found washed up in their hundreds, or sometimes even thousands, after stormy winter weather.

How to identify

These small organisms consist of a deep bluey purple oval disc, known as a float. A thin, semi-circular fin (sail) attaches diagonally across the top of the float and tiny short tentacles hang down from the float into the water below.


A pelagic (open ocean) species commonly recorded around British and Irish coasts in the autumn and winter-time when storms are most common.

Did you know?

The direction of the sail along the float determines which way the by-the-wind-sailor will travel. If the sail runs north-west to south-east along the float it will drift left of the wind direction, if the sail runs south-west to north-east it will drift right of the wind direction!

As a charity we rely on memberships

Memberships help us campaign for better protection and management of our seas.

Join today

Seas in crisis

Plastic-strewn beaches, fisheries on the verge of collapse and the ever growing effects of global climate change.

What The Wildlife Trusts are doing

Mark Hamblin/2020VISION