How to Distinguish from Similar Species: There are no similar species. The attached colonial hydrozoan Tubularia has a similarly structured (though much smaller) polyp but would not be mistaken for this species. The 'bluebottle' found for example in Australia is a similar color of blue but has an inflated float like a Portuguese man-of-war.
Geographical Range: The species is pelagic and usually offshore, though thousands may be blown ashore by strong onshore winds (especially during El Nino), mostly during late spring and early summer. It occurs worldwide in temperate and tropical seas.
Depth Range: Float on surface (pleuston).
Habitat: Worldwide in temperate and tropical seas. Oceanic
History: This species
is a puzzling one. It has long been regarded by many as a
pelagic colony of hydrozoan
polyps similar to Physalia, the Portuguese
study suggests that, instead, it is a single very large hydrozoan polyp
(Order Chondrophora), floating mouth downward and with a chitinous
and sail instead of a column.
If so, it is an extremely large polyp
for a hydrozoan. At any rate, the underside also includes
that bud off
small medusae. The medusae (up to 1.5 mm tall) sink to as far
2000m depth and produce gametes. The developing embryos
and rise back to the surface. This species is oceanic, being
found far offshore. The angled sail makes it sail at 45
the prevailing wind. Some have a sail angled to the left,
to the right. Off California the right-angled form
and these remain offshore in the prevailing northerly winds.
southerly or westerly winds, however, may bring huge aggregations
Velella have symbiotic algae (zooxanthellae)
their tissues, and
also feed on zooplankton. They are eaten by pelagic
as some nudibranchs and bubble-rafting snails. The pelagic
barnacle Lepas anatifera occasionally attaches to
the dead chitinous
floats. This species has many nematocysts
and a few people have reported feeling a sting, but I have handled many
and have never been stung even slightly. The species feeds on
eggs and crustacean larvae.
Kozloff, 1987, 1996
Smith and Carlton, 1975
Francis, Lisbeth, 1991. Sailing downwind:
of the Velella
Journal of Experimental Biology 158: 117-132
General Notes and Observations: Locations, abundances, unusual behaviors, etc.:
Authors and Editors of Page:
Dave Cowles (2004): Created original page