Life Cycle of the NZ Green Lipped Mussel
Saskia OstermeierNZ Green Lip Mussel are endemic (Native) to NZ and live around New Zealand's coastline on rocks and firm surfaces.
A distinctive vibrant green shell, a green lip around the edge of the shells. The male and female differ in color of their flesh, males have creamy white flesh and the females are apricot-colored. They can grow up to 240mm in length.
Life Cycle
The NZ Green Lipped Mussel undergoes enormous changes, during their life cycle, including fundamental changes in shape.
They change from a free-swimming larval form (which swims in the ocean) to a settled juvenile and adult form (which is anchored to one spot).
Mussels spend up to 6 weeks as larvae and can live for many years as adults.
Farmed mussels, however are harvested after about 18 months in the adult form. The Green Lipped Mussel's life cycle starts with the release of eggs and sperm into the water.
A sperm finds an egg and fertilizes it, forming a zygote. This process is known as 'broadcast spawning'. The cells in the mussel zygote start to divide and start to differentiate to form a swimming mussel larva.
When larvae reach about half a millimeter in size, they prepare to 'settle' (attach to a surface). Larvae settle by secreting strong, stretchy fibers called byssal threads, which anchor the larvae to its chosen surface.
Larvae usually settle first on flexible filamentous surfaces such as seaweed.
Mussel larvae are free-swimming. They feed on phyto-plankton and use small hairs called cillia to move around in the water and to help them collect food. Ocean currents can carry larvae hundreds of kilometers away from their 'birthplace'.
From Larvae to Spat
As soon as larvae have settled, they change (metamorphose) from their larval shape into one that's more recognizably Mussel-like. At this stage, they are commonly known as spat.
They also change the way they do things - for instance, they develop gills, which they then start to use to breathe (instead of absorbing oxygen directly through the surface of their bodies) and to gather food.
Even though they have settled onto a surface, spats are still very mobile.
They can move from site to site by crawling around with their foot or by 'mucus drifting' (moving through the water by using threads of their own mucus as parachutes).
As they grow larger, mussels become less mobile and choose a solid surface on which to settle permanently. Their favorite surfaces include rocks, wood (such as wharf post), ropes (on mussel farms) and other mussels (in mussel beds on the sea floor).
Adult stage of the Mussels
Once settled, mussels grow rapidly - from about half a millimeter in length to approximately 24cm (although farmed mussels are harvested when they reach approximately 10cm. The color of their shells deepens over time as they begin to build up their adult shell.
From about 1 year of age, mussels are sexually mature - they can produce and store eggs (orange) and sperm (white) in preparation for spawning. This is why mature female mussels have orange flesh, while mature male mussels have white flesh.
The main food source for Green Lipped Mussels is phyto-plankton - plant-like microscopic organisms that live in seawater in many millions-.
Mussels trap phyto-plankton by pumping large volumes of seawater over their gills. The phyto-plankton get trapped on the gills and is then transported to the mussel's mouth and eaten. This process is known as filter feeding.
Farmed mussels in New Zealand have exactly the same food source as wild mussels.
Mussel farmers don't need to feed their mussels, because the coastal water around New Zealand are very rich in phyto-plankton. Run-off of fertilizers from farms into the sea means that our coastal ocean water contains ample nitrogen and phosphorus to support phyto-plankton growth.
This is one of the main reason why coastal areas such as the Hauraki Gulf, which backs onto land that is farmed intensively for dairy purposes are such good sites for farming mussels.
Predators of the Mussels
Because adults mussels are immobile, they are attractive to other marine organisms as a place to live. Barnacles often settle on the outside of mussel shells and mud worms bore onto the shells and cause blisters.
Pea crabs take up residence within mussel shells, where they steal the phyto-plankton that the mussel has collected on its gills for food.
Being immobile also means mussels are at risk of being eaten. Their hard shell protects them from some would-be predators, but sea stars, carbs and crayfish are all strong enough to access mussel flesh from within the shell.
Spats are also at risk of being eaten by fish with strong crushing jaws, such as snapper.
Pristine waters of the Marlborough Sounds
The NZ commercial mussel industry has grown to a billion dollar industry, regulated under the New Zealand quality assurance programs, which is one of the strictest for shellfish in the world!
AllinFlex NZ uses mussels which are grown in the pristine waters of the Marlborough Sounds, the waters are tested accordingly to the specifications & standards set out by both the U.S. Food & Drug Administration, European Union and NZ Food & Safety Authorities.
No mussel can be harvested from farms without confirmation that the water & shellfish testing during their growing cycle & environmental monitoring have been declared to be safe.
Allinflex NZ mussels are processed in a state of the art factory operating under stringent hygiene and quality control regime under the NZ government regulations & International food processing standards, including the USFDA and European Union.
