Most of us look forward to summer’s warmer waters and the chance to enjoy swimming, snorkeling and diving without being frozen to the bone. However, if you restrict your water-based activity to summer time you are likely to miss out on some of the South Coast’s major underwater attractions.

One of these is the mating behaviour of the giant cuttlefish, which has the scientific name of Sepia apama. Oddly enough, cuttlefish are members of the phylum (or group) of molluscs which includes slugs and snails, as well as oysters, clams, abalone and other marine shell- fish. However, unlike these distant cousins, the cuttlefish are smart and mobile, as are the other members of the class of cephalopods such as squid and octopus. There are many species of cuttlefish around the world, but our giant cuttlefish are the largest of the cuttlefish family and are regularly seen in South Coast waters and other places in Southern Australia.

The giant cuttlefish can grow over half a metre in body length; i.e. not including its tentacles. Like most of its humbler relatives, it has a shell, but it wears this inside rather than outside its body. Most of the familiar white chalky ‘cuttle bones’ that can be found regularly washed up on our beaches are from individuals of this species. The cuttlefish has amazing powers of camouflage, being able not only to change colour rapidly to blend in with its surroundings, but also to modify the texture of its skin so that it resembles seaweed or rock or whatever may be its immediate surroundings.

The cuttlefish is an active hunter, feeding mainly on small fish, crustaceans, other molluscs and worms which it catches by darting out its two feeding tentacles, grasping its prey with the aid of suckers which have claw-like projections and quickly drawing the hapless victim back to its parrot-like beak. In its turn, the cuttlefish can be a tasty meal for larger predators such as sharks and dolphins.

For most of the year the cuttlefish is somewhat retiring. In the interest of self-preservation, it tends to keep out of the way under rocky overhangs or in caves. However winter is the mating season and the cuttlefish then casts caution to the winds (or waves) and puts on a magnificent display to impress prospective partners and to intimidate rivals.

In the month of July, cuttlefish can be seen flashing continuously changing patterns and colours and flaring their tentacles and mantle to make themselves appear twice their normal size. After a lengthy and often competitive courtship display, the male uses a specially adapted arm to pass a packet of sperm to the female. The female lays the eggs and attaches them to the seafloor. They then develop and hatch and thereafter the tiny young have to fend for themselves. Cuttlefish grow quickly and are short-lived, hence the large number of cuttlefish ‘bones’ washed up on our beaches.

The best cuttlefish watching experience I have had was one sunny July day near the Potato Point boat ramp. After having already been in the water for about an hour I was heading back just a few metres from the rocks when I came across three cuttlefish putting on a spectacular display. I hung in the water for ages, fascinated by this amazing site, all the more because it was all happening so close to shore in such shallow water. It resembled nothing so much as a graceful ballet as each cuttlefish swept its flared tentacles in front of the other. On and on it went and, while I had difficulty in tearing myself away, I had been in the water for a long time and was starting to get quite cold.

Near the town of Whyalla at the head of the Spencer Gulf in South Australia, the giant cuttlefish are in such great numbers that watching their mating dance has become a contribution to the local tourist industry. They are not as numerous in our waters, but it is still not unusual to come across a display if you are in the water in July. Remember though that you need to be wearing a decent wetsuit (preferably a 5mm full length), always have a buddy when you snorkel and only enter the water when conditions are suitable.