Blaschka glass model of a by-the-wind-sailor.

This is a hand-made glass model of a jellyfish made by the Blaschkas. You can see the real animal here.

Similar to the Portuguese Man-of-War, the by-the-wind sailor Velella velella is a remarkable kind of jellyfish known as a hydrozoan. The species has been found in the Atlantic Ocean, the Pacific Ocean, the Indian Ocean, the Caribbean, and the Sargasso Sea and floats on or near the surface of the water. It is actually a colony of 4 kinds of animals or polyps: a pneumatophore that acts as a gas-filled float; dactylozooids that form tentacles; gastrozooids that collect food; and gonozooids which produce sex cells for reproduction. The float also has a crest which acts a sail and in this way the colony is driven along by the wind. The direction of the sail along the float determines which way Velella velella 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. The tentacles are covered in powerful stinging cells known as nematocysts which trap and kill food, mainly young fish and shrimps.

In the 1880s Leopold Blaschka (1822-1895) and Rudolf Blaschka (1857-1939), father and son, ran a small workshop in Dresden, Germany. Initially they made costume jewellery and glass eyes for taxidermists and the blind. However, about 1863 they started to make exquisite glass models of marine invertebrates and these soon became their main business. At their height they had salesmen working across Europe and North America and as far a field as Japan and India.

In addition to models of marine animals the Blaschkas also specialised in the production of anatomically correct glass models of flowers and other plants. By 1888 the Blaschka sales catalogue listed over 700 different models. Sea creatures are extremely difficult to preserve in their natural colourful state and thus the lifelike models were in great demand by museums and private collectors. When Rudolf died in 1939 there was no one to carry on the business and production ceased. This model is one of over 40 that are on display in the Zoology Museum at The University of Aberdeen.