This crayfish can grow 10-20cm but some individuals attain a length of 30cm. Colour is variable and depends on water quality, but most take on a greyish-blue to vivid metallic blue colour. This is not an indigenous species and may have negative impacts on our wetland systems by competing against indigenous species. The burrowing activity may cause damage to dams and riverbanks.
European shore crab
A large crab measuring 10cm across the carapace width. The front margin of the carapace has three 'teeth' between the eyes and five prominent 'teeth' along either margin. It is mottled green in colour on its upperside with a semicircular pattern of white dots across the carapace. The underside is yellow or orange. This crab is competitive and has largely eliminated mussels and other shellfish in the area.
Typical crayfish body form with telson (tail) and pincers. The body colouration is usually pale yellow to pale green in colour and the sides of the thorax are very rough. This crayfish averages 15cm in length, but may reach 30cm long. This crayfish is invasive in lakes in Europe and may negatively affect South African wetland systems.
Slender bladder snail
A small aquatic snail with a narrow, pointed shell measuring up to 15mm. The shell is coiled to the left. The shell is brownish with a marbled pattern of lighter blotches. It prefers standing water in canals, ponds and swamps but not river where water runs steadily.
Asian tiger mosquito
A small to medium-sized mosquito with distinctive black and white body. Narrow white bands are prominent on the legs. The wingspan is 5,5mm. Known to transmit various diseases and pathogens, including West Nile virus, yellow fever virus, dengue fever and Chikungunya fever. It also transmits disease to animals.
A common invasive starling found throughout the Western and Eastern Cape Provinces. It favours urban gardens and parks as well as agricultural regions where they feed on a variety of insects, fruits and seeds. This starling is very distinctive as breeding adults have a white-flecked appearance with bright yellow bill and glossy purple plumage around the head and shoulders.
The smallmouth bass is a small predatory fish, reaching up to 60mm in length and 2kg in mass. It is an olive to coppery-yellow colour above, with darker olive vertical stripes and a dusky white underneath. Breeding usually occurs in early summer in shallow waters. Smallmouth bass has caused a decline in indigenous species through environmental degradation and predation.
The Mediterranean mussel inhabits the rocky shores of the Eastern, Western and Northern Cape. Originating from the Mediterranean, these large smooth-shelled blue to black mussels, form dense beds on intertidal rocks displacing indigenous mussels and other small marine species.
The Common Carp is a large freshwater fish, growing up to 1m in length and 24 kg in weight. Both colour and scales are variable in this species. It can be found in much of South Africa, and has had a significantly negative impact on the environment. Competition with other organisms for the same food sources has resulted in biodiversity loss.
The Argentine ant invades urban and agricultural land, and undisturbed fynbos in the Western Cape. A small brown ant, reaching 2 - 3mm in length. Argentine ants feed on honeydew (from aphids and mealybugs) and protein (dead insects). Colonies have several queens and spread by budding. This species has been known to reduce indigenous ant diversity. Reduces the number of seeds produced by proteas.