Researchers think there are about 100,000 giant freshwater crayfish left in Tasmania, although no firm number exists because they live underwater and in remote areas. In addition to their sheer size, this massive invertebrate also has an extremely long lifespan among its kind. Luckily, Tasmanian authorities saw its plight and had the foresight to list the species as endangered some years ago. The worlds largest crayfish, Astacopsis gouldi, also known as Tasmanian Giant Freshwater Crayfish or Tasmanian Lobster. However, historical record does not support the use of this word for this species. It’s been known to grow up to 6 kg, however, these days animals weighing 2–3 kg are considered large and anything over 4 kg as gigantic. Probably the most amazing crustacean in the world. They remain the largest known existing freshwater invertebrates in the world. The Tasmanian Giant Crayfish was featured in "Jurassic River Beast", S1 E7 of Jeremy Wade's Dark Waters. Tasmanian Giant Freshwater Crayfish Facts The name itself gives the most noteworthy fact about the Tasmanian Giant Freshwater Crayfish. Giant freshwater crayfish commonly reach 120 mm in carapace length, although they may get up to 400 mm. Giant freshwater crayfish commonly reach 120 mm in carapace length, although they may get up to 400 mm (Bliss 1982). In Tasmanian Aboriginal language (palawa kani) the giant freshwater lobster is referred to as lutaralipina.Previously, it has been common to use ‘tayatea’ as the Aboriginal name for A. gouldi. Name. Jeremy Wade searched for remaining Crayfish, despite their extreme rarity. Just better. Although a crayfish, the species is locally known as the giant freshwater lobster. Tasmanian giant freshwater crayfish. Shockingly huge. They do not grow to this size quickly, but can live around 30 years. This is the largest known freshwater invertebrate, commonly reaching 500g and occasionally reaching 3 kg (Smithton 1999). The Tasmanian Giant Freshwater Lobster Astacopsis gouldi is the planets largest freshwater invertebrate. They are even reports of them preying on platypus. The giant freshwater lobster — also known as the giant freshwater crayfish — is unique to the island state, can live to the age of 60 and grows to the size of a medium dog. They do not grow to this size quickly, but can live around 30 years (DELM 1999). The Tasmanian giant freshwater lobster is the biggest freshwater invertebrate on earth and is only found in streams and rivers in northern Tasmania. Quite the same Wikipedia. Up to 6 kg!!!