The most recent extension of the distribution of Sabella spallanzanii along the east Australian coast was the discovery of a small population at Inscription Point, Kurnell in the southern part of Botany Bay in 2013 (Murray and Keable, 2013) and later at Bare Island, Botany Bay in 2016 (Ahyong et al., 2017). Reports from Sydney Harbour have to date proved negative. Molecular studies failed to determine if these populations from Botany Bay originated from southern New South Wales or from New Zealand. The populations in New Zealand which are found in several estuaries seem to have originated from southern Australia and not from the Mediterranean Sea based on molecular studies.

An earlier desk top study by Glasby and Lobb (2008) suggested that Botany Bay was a very likely area to be invaded by this species, from domestic shipping, citing the most likely vector and source as commercial shipping from the Port of Melbourne. Alternatively, it could be introduced from New Zealand (i.e. Auckland and Tauranga) and both these scenarios are supported by the molecular data of Ahyong et al., (2017).

Summary Description

Sabella spallanzanii is a large (to 50 cm) tube dwelling worm with a branchial crown formed by two lateral lobes. One lobe is distinctly spiralled and the other one is circular or semi-circular, each with numerous radioles. Radioles lacking paired stylodes and radiolar eyes. The radioles vary in colour from a uniform dull white to brightly banded with stripes of orange, purple and white. The branchial crown can reach 10-15 cm in diameter. Adult worms range in size from 90-400 mm, with the branchial crown accounting for roughly 45-60 mm of this length. Worms found in depths of 10-20 m. The tube of the worm is semi-hardened mucus, which forms a tough leathery tube which increases in size as it grows. It is often covered by many small organisms and becomes wrinkled towards the base. It can even be obscured completely by growth of algae, sponges and other marine life. The tube can protrude up to 40 cm above the sediment and be buried as deep as 10 cm into the sediment. Commonly found in clumps creating a canopy of branchial fans which stretch over the sediment.

A detailed description is given by Knight-Jones and Perkins (1998).

Found in disturbed sheltered marine waters, often in ports and marinas, and appears to be absent from exposed coasts. Lives in tubes attached to rocky substrates or in muddy substrates with tubes attached to small shell fragments. Currently known from Botany Bay and Twofold Bay, (NSW); north coast of Tasmania; Westernport Bay, Victoria; Adelaide region, South Australia and SW Australia. Usually in areas where disturbances such as dredging or boat movements in marinas regularly occur. Populations in these areas are regularly found, although some large populations disappear afterward (Ross et al., 2007). In some cases small populations are found and there is little evidence that they are expanding and may be just represented by few solitary animals, as in Botany Bay. Temperature has been suggested as an important factor in determining its range.  Preferred habitat is in protected areas rich in nutrients and sheltered from direct wave action (Currie et al., 2000).