More information on these pest species can be found on the National Introduced Marine Pest Information System

Name Key Features Impact Habitat What can you do?
Asian Date Mussel/Bag Mussel ( Musculista senhousia ) Shell has zig zag markings & iridescent radiating bands. Shell olive green/brown & is easily crushed. Up to 3cm long. Can form mats on soft sediments smothering bottom communities & altering food availability. Prefers soft sediments but also fouls artificial hard surfaces. Up to 20 m depth. Inspect & clean niche areas & antifoul boat hulls regularly. Clean & dry equipment before transporting & using in a different location.
European Fan Worm ( Sabella spallanezanii ) Spiral fan of feeding tentacles. Flexible, leathery tube. Fan white/pale fawn/orange/banded red/brown. Tubes up to 40 cm long, solitary or in groups. Forms dense colonies consuming vast amounts of food. No known predators in Australia. Fouls aquaculture structures increasing cost for industry. Tubes attached to hard surfaces, artificial structures, rocks, shells & seagrass on soft sediments. Sheltered waters, to 30 m depth. Familiarise yourself with the national best practice management biofouling guidelines. Inspect & clean niche areas & antifoul your vessels regularly. Clean & dry equipment before transporting & using in a different location. Check anchors & other equipment for tangled organisms.
European or Basket Shell Clam ( Varicorbula gibba ) Shells not equal size, one is larger & fits like a lid, overlapping the other. Coarse grooves & ridges. Shell is plump, broadly oval coming to a triangular end. Shell colour is white to pink with radiating red/brown rays. Up to 2 cm long Can form mats on soft sediments smothering bottom communities & altering food availability. Burrows into soft bottomed habitats, may attach to gravel & stones. Intertidal to 150 m depth. Temperate waters. Inspect & clean niche areas & antifoul boat hulls regularly. Clean & dry equipment before transporting & using in a different location.
Japanese Kelp / Wakame ( Undaria pinnatifida ) Frilly sporophyll near base of mature plant. Mature plant only found from early winter to late summer. Strap-like midrib. Smooth thin blades stop well short of base. Generally brown/green. Up to 1m long, sometimes to 3m. Can rapidly form dense forests on any available space & overgrows natives. Cold temperate ocean waters. Lower intertidal to 20 m depth. Rock, reef and stones, artificial structures and aquaculture equipment. Familiarise yourself with the national best practice management biofouling guidelines for your sector at www.marinepests.gov.au. Inspect & clean niche areas & antifoul your vessels regularly. Clean & dry equipment before transporting & using in a different location. Check anchors & other equipment for tangled algae.
New Zealand Screw Shell ( Maoricolpus roseus ) Smooth conical shell. Generally brown, fading to purple/white with age. Broader tapering shell with up to 18 whorls. Grows to 9 cm long, usually ~6 cm long. Densely blankets the sea floor with live & dead shells. Can compete with scallops & commercially farmed shellfish for food. Lying on or partially buried in sand, mud or gravel. Also found in crevices. Low intertidal & subtidal up to 130m depth. Inspect & clean niche areas & antifoul boat hulls regularly. Clean & dry equipment before transporting & using in a different location.
Northern Pacific Seastar ( Asterias amurensis ) 5 arms with pointed upturned tips. Yellow/orange with purple markings & yellow underneath. Up to 50cm across. Aggressive predator of native species & economically important bivalves. Impacts aquaculture & fisheries. Soft sediment but also artificial structures & rocky reefs. Estuaries, bays, rock pools. Intertidal to 200 m depth (usually <25m depth). Prefers temperate but adapted to warmer waters. Inspect & clean niche areas & antifoul boat hulls regularly. Clean & dry equipment before transporting & using in a different location. Ensure all aquaculture livestock is pest free.