A male common cuttlefish courts a female, while another male displays at them.

Not long after my previous attempt to witness common cuttlefish mating, I joined my friends Jelmer and Floor in Zeeland for a second chance, and what turned out to be one of the most beautiful dives I’ve ever made.

I would say we saw around 30 cuttlefish — courting, fighting, mating, feeding, females depositing eggs, you name it — as well as a young lumpsucker, several bluefire and compass jellyfish, and to top it off, I even caught sight of a common European squid darting by!

Common Cuttlefish Reproduction

The common cuttlefish Sepia officinalis spends most of its life by itself in the depths of the ocean. But in spring, around the time when the water temperature reaches twelve degrees Celcius, large numbers of cuttlefish gather in the shallow waters of the Oosterschelde (Eastern Scheldt), an estuary in the south of the Netherlands: the spawning season has arrived.

To romance a female, a male will hover over and alongside her while softly drawing his arms over her mantle, head and arms. Eventually he will grasp her and mate with her. Using a modified arm, known as the hectocotylus, the male passes spermatophores to the female to fertilize several eggs.

After mating, the female deposits eggs one by one in clusters on seaweeds, shells, or even debris. She blackens them for camouflage with the same ink that cuttlefish use to cast a smoke screen against large predators. The male often remains at her side for some time, but he has no romantic intentions. He is merely trying to prevent her from mating with another male.

A female common cuttlefish deposits an egg

After several days she has deposited hundreds of eggs, which have been fertilized by a number of different males. For her this is the end of the line; she will die shortly after spawning. Some of the males will retreat to deeper waters to return for another reproductive bout the following year. Internal shells of the dead animals, known as ‘cuttlebone’, wash up on shore.

Two or three months later the eggs will hatch. The hatchlings are already highly developed and start catching small prey such as shrimp soon after hatching. For good reason, because in the following months these thumb-sized cuttlefish will have to grow to some twenty to thirty centimeteres in length, before they too return to the shallows of the Eastern Scheldt for a new spawning season.