CANBERRA, March 20 (Xinhua) -- Australia's national science agency has asked for regular citizens' help to document shark egg cases that wash up on beaches.

The Commonwealth Scientific and Industrial Research Organization (CSIRO) on Monday launched the Great Eggcase Hunt, calling on citizen scientists to find and record cases.

Egg cases or capsules surround the eggs of oviparous sharks, skates and chimaeras through the entire gestation period, which can range from three months to three years.

They can range in size from four to 25 cm and can be smooth, ridged or corkscrew-shaped depending on the species.

After fully developing inside the oviduct, the case is deposited outside the body for the remainder of the incubation period after which the capsules are discarded.

Helen O'Neill, a biologist from the CSIRO Australian National Fish Collection, said that by recording case sightings on beaches citizens could help researchers discover what the cases of different species look like.

"Egg cases are important for understanding the basic biology of oviparous chondrichthyans, as well as revealing valuable information such as where different species live and where their nurseries are located," she said in a statement.

The hunt is an initiative of British-based charity The Shark Trust, which is focused on the conservation of sharks, skates, chimaera and rays.

Each egg case has a unique morphology that can help researchers describe and name species.

"At the Australian National Fish Collection, we are matching egg cases to the species that laid them," O'Neill said.

"Egg cases found washed up on beaches have likely already hatched, died prematurely due to being washed ashore or been preyed on by creatures like sea snails, who bore a hole in the egg case and suck out the contents." Enditem

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