The marine life within Alderney’s marine environment have very weird, wonderful and complex life cycles.

Barnacles are crustaceans which live on Alderney’s rocky shores attached to rocks and boulders. They begin life by hatching out of eggs as free swimming larvae (known as nauplius) in the sea. After 6 months, the Nauplius change into crawling marine invertebrates (known as cyprid) which scuttle about the rocky shores looking for a nice spot to settle. Once a spot has been found, the cyprids finally turn into adult barnacles and will settle there for life.


Limpets live throughout Alderney’s intertidal beaches, bays and rocky shores. They also begin life by hatching out of eggs in the sea as free swimming larvae, but are all males. After a few days they find their way to the intertidal zone and grow into their limpet/snail like form; a hard shell with a large muscular foot. At the age of 2, some limpets then turn female and start to lay eggs to begin the life cycle all over again.

Sunfish are giant dinner-plate fish that roam the oceans, including Alderney’s seas. They begin life from an egg and hatch out as very tiny spiky fish. Over time, they lose their spikes and become big bizarre looking fish!

Baby sunfish

Ocean sunfish (Mola mola) found in open ocean, California, USA, Eastern Pacific Ocean

Ocean sunfish (Mola mola) found in open ocean, California, USA