There's an indistinct flash to my left. I'm in only 4m of water, but a week of unsettled weather has left a sheet of mixed fresh and salt water some 2m deep. Plankton is starting to flourish in the nutrient-rich layer and the visibility is down to almost zero.
Under that, the water is a little clearer and I can see about 4m around me, but it is dark and a bit gloomy.
I am kneeling in a patch of kelp on a stony bottom, sorting out my camera's exposure. Then the flash catches my eye.
Somewhere out there, unseen, I know that there is another photographer - Alan James. I had entered the water with him, but we were separated in the minimal visibility. Not that it bothered either of us, as we're used to working alone.
However, I suspect from the flash that Alan has found some of the cuttlefish which gather in this small Devon bay, and are the reason we are both here.
The common cuttlefish, or Sepia officinalis, as it's know to men in lab coats, is a common animal around the UK. It's often seen resting in sand or hunting around rocky reefs.
Usually known to non-divers only as a white porous bone decorating a budgie cage, officinalis is a fascinating creature with intelligence up there with the likes of house cats, foxes and octopuses.
A good-sized specimen, in most divers' opinion, would get up to about 15cm, but what I hoped to find would be much larger than that.
It was just after 7am on an early May morning. The beach and harbour front was deserted except for a couple of fishermen and a bull grey seal which patrolled the fringe of the sheltered bay.
The sea was flat-calm and almost at low water, so Alan and I stumbled over the stony ground, treading as carefully as drunks on a cobbled street, and entered close to the slipway.
We had no idea where the cuttlefish would be, but from past experience we knew that they were likely to be around 20m from shore on the edge of the 4m shelf, where the kelp gives way to a different kind of seaweed known as sea oak (Halidrys siliquosa).
The water was distinctly green, the light levels reasonable (the sky above was cloudless at the time), and around 12íC - chilly, but not too bad.
We were right in the middle of the cuttlefishes' active breeding season, which starts some time towards the end of March and runs to the end of May. When they arrive is down to factors as yet unknown, but there is around a month of activity before the animals disappear back to the edge of the continental shelf or, in many cases, die.
Breeding cuttlefish are big, and when I say big, I mean pet-cat big.
The males (larger than the females) can grow to 60cm in length and achieve this size within two years.
During the first year, the juvenile cuttles spend the summer gaining size and weight in shallow coastal waters.
Around October, as the water cools, they migrate to the Bay of Biscay, and the edge of the European continental shelf, where they over-winter in an area known as Hurd Deep, where the UK government and radioactive reprocessing plants have dumped chemical and radioactive waste.
As the days start to lengthen, both sub-adult and mature adults migrate inshore again. Officinalis is found alongboth shores of the Channel, into the Bay of Biscay and up the western coasts of Ireland and the UK.
They find this small bay, and many others like it, enticing - possibly because of shallow water, which warms faster in the spring; the abundance of their favoured anchorage points; and its sheltered position.
The breeding ritual must have been carried out here for thousands of years, yet its discovery by humans happened only by accident. A few years ago some divers had to visit the uninteresting side of the bay, as bad weather had blown out the better side, and they came across gangs of male cuttlefish fighting for the less numerous females. The spectacle has drawn divers to the area ever since.
That's exactly what I hoped to see and photograph, and so I set off in the direction of the flash and found Alan along with 10 or so large cuttles, which were milling around two others.
The male of the couple was much larger than the female and loomed over her. Using Popeye-esque outer arms, he shielded his prize from the other males who were circling the pair like wannabe Romeos in a nightclub (cuttlefish have eight arms and two tentacles - tentacles differ from arms in having sucker plates at the end).
This male searched the water with his strangely shaped eye for others who would, given the chance, muscle in and take his female from him. He flexed his outer arms and splayed them out over his woman to ward off the others, who were baying for some lovin'.
Males must stay with their female after mating to ensure that no other male removes his sperm before it can fertilise the female's eggs. In fact a male remains with his female all through the laying process.
As in any nightclub, males outnumber females and lone, or rogue, animals roam through the bay, as if the last slow dance is being played, searching for either newly arrived females or an unwary or smaller male who they can bully away before stealing their woman.
Cuttlefish are well known for their colourful body displays, but throughout the mating season the males and females display a brown and white zebra pattern. When the males start to square up, those patterns become increasingly vibrant. And they go nuts when a fight is on. I watched the males manoeuvre, flashing their dynamically coloured skin at each other, and all the time the female was hiding beneath her suitor.
It all seemed fairly civilised until one male overstepped some unknown mark and made a deliberate move on the couple. The protecting male rushed towards him, arms open ready to inflict a bite with his beak, which is designed to crush the hard shell of a crab.
The rogue suddenly became the attacked but, sensing the danger, instantly mirrored his opponent's action.
The two locked arms and tentacles, and for a second tussled violently. The rogue male then broke off, squirted a jet of ink into the water and fled, leaving the original male to resume his place above his female.
All this happened so quickly, and so soon after we had found the animals, that I simply wasn't prepared and didn't even get a shot off during the action.
For the rest of the dive the animals moved around but didn't come back together, so I exited the water with little exposed film, but elated that the animals were where we thought.
After breakfast I was back in the water and found myself alone again. I swam past the kelp fronds and into the forest of chord weed that grows on the top edge of the shallow "drop-off".
At less than a metre, it's about as much of a drop as a roadside kerb outside an old folk's home, but the tide had started to come in and there was an extra 20cm of water with which to contend. Thankfully, in the bay there is no current and the maximum depth of 5m meant that I was in no danger of running out of time - just as well, as the only marine life I could see were a pipefish and two wrasse. There was no sign of a cuttlefish.
I swam to the right, searching the edge of visibility for any movement, but found nothing except a small cuttlefish. Sensing that I'd gone too far to the right, I turned back and retraced my route.
After 20 minutes I was becoming despondent. I'd seen little but the ubiquitous wrasse.
Then, about 5m away, I caught sight of a lone cuttlefish moving with some determination away from me. I followed at a distance and came across more.
Finally, after swimming around an area the size of a not-so-large living room for 25 minutes, I had rediscovered the group of rogue males. What I'd have given for some decent visibility.
The males were in a loose formation, milling around the area but doing little. So I moved through them and headed further north in a bid to find a couple, but failed. I settled to watch the males and took some single images, but with nothing happening it was difficult to get enthused, so I broke off and headed back to shore.
I waited for the tide to come up, hoping that it would bring clearer water and more females. I went back in as the water was nearing high tide and swam towards one of the mooring buoys I had seen from below on my first dive.
Once over the drop-off, I descended and landed on the seabed close to the buoyline. It gave me a good reference mark (if I could find it again), and I set off northwards this time, hoping to find a group with at least one pair.
I picked up the first cuttlefish about five minutes later. Moving deliberately, he swept past me and I followed. I soon found the reason for his hurry.
Six males had gathered around a couple. The large male protecting his female displayed deep brown, almost black, lines across his back and his large outer arms were spread wide to ward off anyone willing to try it on.
I was ready and started shooting images. I closed on various males who were edging nearer to the happy couple. Each male blazed in colour-coded displays eager to beat the other males to the female who was, by now, hiding within the weed and probably wondering when the riot would start.
Above, her suitor was having a difficult time keeping the others at bay. I knew something was going to happen and I waited.
Bang! The guarding male, like a drunk whose pint has been stared at, shot forward and attacked another. Their tentacles locked and the bodies twisted. I fired my camera, again and again.
Then the flash stopped. I thought at first it needed a few seconds to recharge, but the film was finished. The action was over as fast as it started and I just hoped I had a decent shot - thankfully, I had!
As the morning wore into afternoon, there seemed to be less aggressive activity. The males that had roamed the shallows like a pack of youths wasted on cider and funny cigarettes dispersed, leaving the couples alone.
I came across one pair. The male, sporting a vicious facial injury, seemed comfortable with my presence, so I settled on to the seabed and watched.
Almost a metre long, he caressed the smaller female gently with his large arms. If I knew no better I'd have said there was affection there, but in truth he just wanted to make sure she laid eggs fertilised by his sperm.
The chromataphors under their skin were going mad as they waited for an egg to develop. Their faces were alive with rapid colour changes that could have been a conversation into which I wasn't tuned.
On my video, I could just make out this array of subtle changes, like rain pelting the surface of a puddle. In the female these colour changes intensified just before she moved in to lay an egg.
The cuttlefish in this bay seemed to prefer the sea oak weed over all others. The thick bushes of brown filamentous algae were thick with cuttlefish eggs, whereas other weed was completely free.
In other areas the females lay on ropes, cuttlefish pots and sturdy low-lying algae. They seem to avoid kelp or the fronds of chord weed that also proliferate in the shallows.
The female lays single eggs through what we would call her mouth, but is in reality a multifunctional orifice. She pushes into her chosen patch of weed every five minutes or so, grips a stem with her arms and guides a cherry-sized egg into place. Its sticky outer shell adheres to the weed. She reverses out and then makes two blows, as if trying to catch her breath or clearing the orifice of detritus left from the egg-case. All the time her male stood watching her - and me, as I tried to photograph the event.
Each egg case holds one offspring, which develops over early summer. The egg is camouflaged with black ink to disguise it, and possibly to protect the embryo from harmful UV radiation from the sun. During peak breeding periods the female can run out of ink. Sometimes a few eggs are produced without ink and are milky and translucent.
The eggs mature in early summer and take 80-90 days to hatch. The newborn juveniles are tiny but fully formed, and start to eat live food as soon as they break through the leathery eggshell. They stay in the shallows, hiding in the weeds, feasting on small prey and doubling in size every week. In late summer, adolescents maraud, feasting on invertebrates and juvenile fish. They are found all down the English Channel and up the west coast.
At the end of October they start to move out into the mouth of the Channel to make the most of deepwater hunting grounds where prey proliferates in the cold months. Sub-adults reappear at the same time as the breeding stock and start to feed in the shallows again.
During this year of their lives,both males and females start to mature. As they migrate offshore again, the females are fully sexually mature and the males well on their way. They return as sexually mature animals in early spring, travelling rapidly close to the surface to reach their chosen breeding grounds.
After mating, most common cuttlefish die. Their bodies sink into holes and depressions in the seabed, to be picked clean by the very animals on which the juveniles and adults had fed for the past two years. In stormy spring weather, hundreds of cuttlefish bones can be washed ashore along the south coast.
I have yet to see cuttlefish eggs hatch and the young migrate from the shallows. Each year hundreds must make it, but hundreds are also caught before getting the chance to mate.
There is a fishery for breeding cuttlefish that uses traps like lobster cages. These trap males by using a female placed inside. This year divers were suspected of breaking open some cuttlefish traps to release the trapped animals.
It annoyed the fishermen, though I hear that the cuttles were quite pleased.
Most of the cuttlefish catch goes to Spain (everything that comes out of our waters seems to these days) where it is eaten in the same way as calamari (squid). I find that about as bad as Koreans eating dogs or Chinese eating cats, but that's just my opinion.
Cuttlefish show intelligence. They are supreme marine predators, and until recently enjoyed a stress-free life without a particularly large fishery attacking them during the breeding season. Fisheries are non-specific and target all the males including the healthiest, which prevents them from breeding.
I don't agree with fishing in breeding areas and during the breeding season, but with other stocks dwindling fishermen are turning to unexploited species to make a living. Whether that's morally right I leave up to you, but also consider where they spend the winter.
The shame is that they are killing what I reckon is one of the most endearing marine species. I've seen officinalis specimens all round the country. They can be seen resting in the sand, hiding in kelp, even hunting at night, but until I witnessed them mating, I had never really got to know them.
If this fishery is stepped up, you may never get the chance.
Lonely heart males with a roving eye
A male defending his female from a rogue male
Two males locked in combat (leave it, Darren!)
Two cuttlefish glide gracefully along. They communicate with each other through rapidly changing skin patterns
A female enters oak weed to lay her eggs while a male stands guard.
Cuttlefish egg cases