This tiny seastar, called Patiriella vivipara is listed as endangered under the Threatened Species Protection Act 1995.
What is P. vivipara?
It is a tiny orange-yellow seastar, with adults only reaching up to 13mm across. It is endemic to Tasmania which means it is only found here. The name P. vivipara comes from the seastar's ability to produce live young instead of eggs. This is known as viviparity. The newborn seastar is a tiny replica of its parent. This is Tasmania's only known endemic, vivaparous seastar so it is very special.
P. vivapara was first described from the Pittwater area by A.J. Dartnall in 1968. The seastar is only known to have been recorded in five locations in Tasmania. These are: Roches Beach, Lauderdale; Pittwater Lagoon, Midway Point; Tesselated Pavement, Eaglehawk Neck; Fortescue Bay and Powder Jetty, Howden. Despite searching it has not been seen at Howden since the development of an aquaculture farm and changes to the foreshore occurred.
Why is it a threatened species?
P. vivipara is threatened because it only occurs in a limited area. All the known populations occupy less than 3 hectares. They are restricted to rocky reefs in the tidal zone and seem to prefer living under rocks near the high tide mark. This puts them at great risk from changes to their habitat. For example, they are at risk from pollution such as eutrophication or sedimentation which are threats at Pittwater. Another threat to seastars is from collectors who collect specimens for aquariums. It is also thought that the introduced NZ seastar P. regularis could be competing with it. This seastar came to Australia in a batch of oysters earlier this century.
What is being done?
Research has been undertaken by Christine Rowland of Marine and Coastal Research Tasmania. A number of people have been researching the seastars abundance and current distribution as well as physico-chemical factors such as temperature, salinity and habitat type. This type of research is necessary so that suitable recovery plans can be developed and implemented to prevent this species from becoming endangered or extinct.
It is very important that local people are educated about marine species, especially about the importance of not collecting specimens. Many of our invertebrates are becoming threatened through over collection, especially butterflies, coral and other marine life.
Another seastar we may soon see included on Tasmania's threatened species list is Smilasterias tasmaniae. There are 3 dried specimens at the Australian Museum in Sydney, believed to be all that remained of a species last seen in the 1960s. Then in 1994 the species was 'rediscovered' by C. Rowland here in Tasmania. She considers them likely to be listed as vulnerable.
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