Mating commences in Winter when large numbers of cuttlefish gather on the shallow near-shore reefs. Rival males become aggressive with one another, flaring out the web membrane between their tentacles and turning vivid colours. Then, they circle one another, copying each others movements.
The larger and more colourful male wins the encounter and neither is harmed. Sometimes however, some males become more violent and one male cuttlefish tries to bite his rival. To attract females, the males splay their tentacles and use all of their colours in an effort to impress the females.
Cuttlefish mate head to head and when in position, they lock their tentacles together. The male places a sealed sperm packet into the pouch just below the female's mouth.
 The female then retreats into the den which is usually a deep crack or fissure in the rocks, or even a small cave to spawn. There she draws each egg out of her mantle individually and passes it over the sperm. She lays up to 200 eggs.
The male cuttlefish often becomes rather aggressive when guarding a female cuttlefish he has mated with, until she spawns. He blocks the entrance to the den while the female is laying her eggs to stop other males washing out his sperm with their siphon and then inserting their own sperm packet.
The lifecycle begins with newly fertilized eggs hanging from the rock in dense clusters. They are white and are coated with a sticky, gelatinous material. Within the eggs, the cuttlefish soon develop and after 4 months, they hatch.
The cuttlefish are 25 millimetres long and have all the traits of their parents. Predation rates are high and very few of the newly hatched cuttlefish survive past their first few hours. Those that survive grow quickly and live in the deeper water.
The new adult cuttlefish are ready to spawn at between 18 and 24 months of age. After spawning, the females soon become lethargic and their body quickly deteriorates.
Overfishing and pollution are a serious threat to cuttlefish populations because the cuttlefish are so short-lived and only spawn once in a lifetime.
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