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By-the-wind sailor

Distribution : Mediterranean · Atlantic Ocean · Indian Ocean · Pacific Ocean · Caribbean Sea

A crown that heralds bonito: that is the association preserved in the Japanese name katsuo no kanmuri. Along Japan’s coasts, the arrival of the by-the-wind sailor has traditionally been linked to the approach of warm waters favourable to bonito fishing. In 1970, Robert Bieri described this connection in an article based on observations at Shirahama, where sailors working on glass-bottom boats had also helped him. The common name preserves a way of reading signs at sea, quite unlike the “little sailing boat” names found along European coasts.

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Habitat of By-the-wind sailor Habitat
Open water
Depth range of By-the-wind sailor Depth
0-0 m
Biological group of By-the-wind sailor Group
Ecological role of By-the-wind sailor Role
Predator

Average size

5 cm

WHAT DOES IT LOOK LIKE?

An angled sail rises above the flat, translucent blue base of the by-the-wind sailor (Velella velella). Its thin rigid wall gives the whole structure the outline of a little sailboat.

This form brings together a colony of small animals. It generally measures 2 to 7 cm.

WHERE DOES IT LIVE?

It lives at the surface in the open sea, carried by winds and currents. It occurs in many temperate areas, particularly the Mediterranean. Under favourable conditions, it may be brought towards the coast in large numbers, sometimes washing ashore en masse.

WHAT DOES IT EAT?

The sail is the by-the-wind sailor’s most conspicuous feature, but capture occurs below the float. Peripheral polyps carry tentacles armed with stinging cells. They take copepods, small gelatinous animals called appendicularians and fish eggs. Catches are passed to the central feeding polyp. The colony also receives organic material produced in light by its symbiotic microalgae. Prey capture and photosynthetic supply provide complementary routes of nutrition.

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By-the-wind sailor

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DEPTH HABITAT PHYLA ECOLOGICAL ROLE