(Linnaeus, 1758) : By-the-wind
Phylum Cnidaria / Class Hydrozoa / Order Anthomedusae / Family Velellidae
The float and surrounding tissues are endowed with an attractive deep blue pigment. The float contains a series of sealed air chambers that provide buoyancy. Total width of the floating polyp is usually less than 6 cm. Beneath the float is a grouping of several types of zooids, colored brown by the presence of zooxanthellae. A large central mouth is surrounded by shorter reproductive stalks with mouth openings that bud tiny adult medusae that produce eggs and sperm. Multitudes of tiny brownish-green medusae that never grow to more than 3 mm tall are cast off (last photo). These then release the eggs and sperm that produce free-swimming larvae which eventually develop into more floating polyps. It's not known if a planula larva is produced initially, but during the early stages oil droplets are formed that bring the young Velella to the surface. Dangling beneath the rim of the float are hollow tentacles that ensnare fish and invertebrate eggs, copepods and appendicularians. Velella is found in warm and temperate seas throughout the world. Although not dangerous to people, it's best not to handle them or touch your face or eyes if you've been touching beached individuals since some irritation may result.
All photographs © David Wrobel and may not be used or copied without permission!