southern rock lobster
Commonly known as a “crayfish” or just “crays”, Southern Rock Lobster (Jasus edwardsii) are a species of spiny lobster native to the Great Southern Reef and New Zealand. These crustaceans have long spines projecting forward from the front of the head but unlike “traditional” lobsters, do not possess the large pincers on their first pair of walking legs.
The deeper the darker
Living in the cold, nutrient rich waters of the Great Southern Reef, Southern Rock Lobster require reef habitat with an abundance of kelp and crevices to call home. The colour of their carapace varies slightly depending on where they decide to set up home. In shallower waters, they tend to have a striking redd-ish purple hue, while those in deeper water have a stronger purple tone that fades into a creamy yellow colour.
Careful crustaceans
Feeding mostly at night, these omnivores tend to eat bottom dwelling invertebrates like mussels and abalone, other smaller crustaceans, sea urchins, worms and algae. During the day they will hole up in deep crevices along the reef and as adults do not stray far from their home region as they are not only tasty to humans, but also other predators like sharks, octopuses and large fish species like morwong, wrasse and ling.
Sought after seafood
Known for its delicious sweet, delicate white flesh, crayfish are an important commodity for wild fisheries and locals alike during cray season. An important asset to the economy in Australia, the aquaculture industry has been researching how to sustainably farm these spiny lobsters for years as they have extremely high commercial value.
Berried breeders
It is due to their long and complex reproductive cycle, that the aquaculture industry has not been able to successfully farm them at this point. Their mating season begins in the spring with the gestation period lasting around 4-6 months. Fertilised externally, the female carries the eggs, which are attached to the pleopods, or swimmerets, underneath her tail. Depending on the age and size of the female lobster, she can fertilise up to 1,000,000 eggs. During this time, she is referred to as “in berry” or “berried,” and she cannot be harvested by any fishermen, commercial nor recreational and must be thrown back.
Long journey for larvae
Once they hatch, the tiny babies begin their metamorphosis into larvae and begin their long journey to become a juvenile lobster. Active swimmers, the larvae make their way to the ocean surface where they change into the second stage and are dispersed widely through ocean currents. At this stage they are carried far out to sea beyond the continental shelf, therefore they could end up thousands of kilometres away from where they left the original female lobster. This phase can last anywhere from 1 to 2 years, and at the end they moult into a transparent puerulus larvae, a planktonic organism that resembles a tiny lobster, but still lives within the water column.
Image: Dant Fenolio
Moulting to maturity
The puerulus stage is when the organism must swim back to the coastal reef from the deep ocean. Once they find the reef, it triggers another moulting – at last – into a pigmented juvenile spiny lobster. A young, immature lobster will molt about 25 times a year. These juveniles live near the bottom of the reef and their growth into a mature adult is slow because of the cool waters where they live. To reach maturity it will take at least 3 years, but could take up to 10 years to reach the minimum size at which they can be harvested. The Southern Rock Lobster can begin the breeding cycle when their carapace measures between 60-70 mm in length.
Fast Facts:
Species: Jasus edwardsii
Family: Palinuridae (spiny lobster)
Order: Decapoda (decapod)
Feeding: Mussels, abalone, small crustaceans, worms, algae
Habitat: Rocky reef with an abundance of kelp and deep crevices
Distribution: Australia and New Zealand
Special Power: Moulting armour
Explore more of the Great Southern Reef
People
Impactful people with a close connection to the Great Southern Reef.
Places
Feature locations along the Great Southern Reef.
Marine Life
The weird and wonderful creatures found along the Great Southern Reef.