When walking on the beach in Plettenberg Bay different kinds of shells from marine animals can be found like Cuttlefish bones, mussels, clams and the most attractive of all, the pansy shell (Echinodiscus bisperforatus). The pansy shell is an icon for Plettenberg Bay and is the symbol for the Bitou Municipality. Even though they are called ‘shells’, the pansy is in fact the skeleton of a sea urchin. They belong to a group of burrowing urchins (Clypeasteroida) and live in shallow sheltered bays and estuaries. The name pansy shell comes from the five-petal flower pattern they have on the top of their skeleton. They are related to the urchins known as ‘Sand Dollars’ which are found in the United States of America.
Pansy shells can be found along the south coast of South Africa, up to Mozambique. In South Africa pansy shells have been found in Mossel Bay, Knysna, Plettenberg Bay, and St. Francis Bay as well as a few sites along the Wild Coast Transkei and Durban. Pansy shells are flat sea urchins and they feed on microorganisms in the sand. During a study of the pansy shell population in Plettenberg Bay in 1991(Bentley A.C and Cockcroft A.C.), two colonies were studied, one along Robberg Beach and one on Lookout beach. It was found that pansy shells occur in waters 4-10 m in depth and lie buried in approximately 5 cm of sand (non were found on the sand surface). The study also showed that they seem to live in patchy colonies with some areas having a high density of pansy shells, and others had none.
Like most echinoderms, pansy shells are broadcast spawners, meaning that the females and males release their eggs and sperm into the water simultaneously. The pansy larvae will spend months in the water column growing in size and searching for a suitable habitat to settle on and metamorphose into their adult form. Pansy shells prefer fine, well sorted sediment that is mostly found in log-spiral bays of the southern and eastern coasts of South Africa.
Pansy shells were classified as an endangered species in 1973 in South Africa and protected by the Sea Fisheries Act of 1973: No. 82. In 2004 their conservation classification was downgraded from ‘endangered’ to ‘protected species’ under the Biodiversity Act, 2004 (Act 10 of 2004). To qualify for protected species status in South Africa the species needs to be indigenous, of high conservation value or national importance and requires national protection.
Pansy shells are at risk of over exploitation through their collection for souvenirs, scientific investigations and the aquarium trade. To collect washed-up shells for souvenirs does not necessarily effect their survival because at this stage they are already dead. However, the collection of live specimens for the purpose of drying and selling can have severe consequences for the survival of the species and it is illegal to do so without a permit. Scientist also collect marine organism to try to find useful compounds to make medicine (cure for cancer), if this is not controlled properly there is chance of over collection of the shells.
By Ocean Blue Crew
– Bentley, A.C. 1998. Reproductive cycle and gonadal histology of Echinodiscus bisperforatus along the southern coast of South Africa. Echinoderms, San Fransisco. Mooi, R. and M. Telford (eds.). P. 571-576.
– Bentley A.C, Cockcroft A.C. 1994. Sublittoral sand dollar (Echinodiscus bisperforatus) communities in two bays on the South African south coast. S.A. J. Zoo. 30 (1):5-17
– James D.B Pearse J.S. 1969. Echinoderms from the Gulf of Suez and the Northern Red Sea. J. Mar. Biol. Ass. India, 11 (1&2): 78-125.
– National environmental management: Biodiversity act, 2004 (act 10 of 2004): publication of lists of Critically endangered, endangered, vulnerable and protected species. Government Gazette, 23 February 2007. NO. R. 151
– Vromans, D.C. Maree, K.S. Holness S. Job N. Brown A.E 2010. The Garden Route Biodiversity Sector Plan 2010 for the George, Knysna and Bitou Municipalities ISBN 978-0-9869776-1-9