Here is the piece I mentioned that I’d written on the Violet Snail Shell for “The Buzz”:
While my son and family were holidaying at Betty’s Bay this year, his elder daughter Amelia, aged ten, decided to do a project on “floating shells”. To her delight, she found numbers of pretty Violet Snail Shells (Janthina janthina) on the beach, together with their prey, the bluebottle, or Portuguese-man-of-war. These snails are in turn preyed upon by birds, fish, sea turtles and other molluscs.
Janthinas have light, fragile shells, growing to between 3-4 cm in size, depending on water temperature. Their bodies are dark purple to black in colour and have a rubbery, slug-like texture. With their “feet” or mantles, they agitate the sea water to create tiny bubbles which they join together with mucus to form rafts, from which they suspend themselves, allowing them to float on the ocean surface. Other common names for this sea snail are Bubble Raft Shell and Purple Storm Snail.
These fascinating creatures spend almost their entire lives at sea, unless washed up onto the shore after unique storms or when an onshore wind has been blowing for a few days. They are all born male and later develop into females. The males release their sperm into a case which drifts to the female, allowing fertilization to take place. The eggs develop internally and the tiny snails are born live and able to build their floating rafts immediately. In the Indian Ocean, there are huge concentrations of these Violet Snail Shells, bluebottles and jellyfish being swept along by the Agulhas current.
With best wishes, Hilary Mauve.
P.S. Recently, Amelia put on a display of her Violet Snail shells at the British Shell Society and was awarded the cup for the Best Educational exhibit on show. This is possibly the first time a child has won a cup that is in a class open to adults as well.