Dive if you dare - the reef at night

As the little sister of two mischievous brothers, I’ve been subject to my fair share of practical jokes. So when many years ago, one of them suggested that we go night snorkelling, I thought “Ha! I’m not falling for it this time, what a ridiculous idea, we won’t see anything”. Then I was given an underwater torch and proved completely wrong.  The reef never sleeps; the familiar faces of the day are swapped for weird and wonderful creatures of the night. Jump in about half an hour before sunset and you’ll see the changeover, the fish take on a new lease of life, rushing around like maniacs, chasing each other and catching their dinner before bedtime.

Twilight feeders have an advantage; their light-loving prey cannot see properly in the fading sunshine, and their own nocturnal predators have not yet woken from their slumber. There is a word for this - Crepuscular- it sounds like some sort of disfiguring disease, but no, it’s used to describe an animal active mostly at twilight.  (Predictably it’s derived from Latin, which was absolutely my worst subject at school. Latin is annoyingly used extensively in Biology so my advice to mini Marine Biologists is to stay awake during Latin classes - they’re not lying, it’s useful!)

Groupers are often crepuscular feeders; if you stand on the jetty near our Park Hyatt Maldives Hadahaa sign you will often see the big daddies terrorising schools of innocent baitfish peacefully resting in the shallow waters.  Sharks have excellent night vision too and are particularly fun to encounter in the dark; like thieves in the night their eyes glow with menace. They have a reflective layer behind the retina called the “tapetum lucidum”, consisting of lots of tiny little plates covered in the splendidly shiny substance “guanine”. This multitasking molecule is not only found in sharks’ eyes, but it’s responsible for shiny things the world over, from the sheen of the shiniest fish to cosmetics. Even more incredible, it’s a vital component of DNA; does this mean that DNA is sparkly? Sadly I think not.

Nocturnal fish are usually carnivores, particularly if they feed on zooplankton. After dark, the bigger more delicious plankton rises from the deep, you can see it twitching and wriggling around in the beam of the torch. Herbivores such as parrot and surgeon fish are almost always diurnal, probably because finding food is easy but they need to be able to see what is edible and what is not. At night parrotfish really do bed down for the evening; they hide by wriggling into cracks in the coral and thanks to their lack of eyelids they fall into what looks like a “zombified” trance.  Some species of parrotfish sit inside a gooey bubble of mucus which is thought to prevent their scent from traveling through the water and also wards off the attack of blood sucking isopod parasites.  

Ugly squelchy things seem to prefer the cover of darkness too. Yesterday we saw the Maldivian sponge snail, and last week we came across a pair of mating sea-hares – giant slugs which can reach up to 30cm in length.  Many armed monsters such as imperial urchins and delicate feather stars emerge from hiding and little shrimps chirp away, their eyes glistening from the crevices. Part of the fun of night diving or snorkelling is that it allows you to focus your attention to only the small patch of reef illuminated by your light; so invariably you notice the detail of things.  Bioluminescent plankton produce the most magnificent magic trick of all; if you were to turn off your torch and flap your arms around in the dark silky water, little flashes of light no larger than pin pricks start appearing all around you - a truly beautiful reminder of the wonder of nature and how much life and excitement there is to find in the ocean.  

Twilight diving on the Hadahaa house reef

Romance on Hadahaa's Reef

 Flying into the Maldives on my own is fun for two reasons; to view the intricate web of islands and coral reefs from the air is incredible, but even more entertaining are the sympathetic looks I receive from honeymooning couples. I hear whispers of “Poor girl, obviously been jilted at the altar” - it’s even better if I encourage the rumours with dramatic sniffs. The Maldives is a country where things are made for two; there’s exquisite luxury, absolute privacy and the seductive sound of lapping waves on deserted beaches. It’s therefore a challenge not to fall in love. In this remote part of the world, romance is big business.

Underwater, the fish are similarly one-track-minded and their agenda goes something like this:

1. Find food
2. Prevent oneself from becoming food
3. Mate

By human standards, reef animals have some pretty wild habits. There is a particular penchant for sex-change, multiple partners and erotic mating rituals that can leave one or both parties quite severely injured.

Switching from girl to boy is particularly widespread amongst Parrotfish. Transsexual Parrotfish are easy to spot snorkeling on the house reef as they change not only their sexual capabilities, but also their skin, adorning themselves with a brilliant array of rainbow colours. Although some are born male, others have a go later in life, thus becoming a “super-male”. These “super-males” are the leaders of the pack; older and therefore larger than their original counterparts they can easily dominate and outcompete when it comes to winning the hearts of the ladies. Unfortunately for some, bigger really is better. This phenomenon known as sequential hermaphroditism makes sense; the number of babies a female can parent is limited by the number of eggs she can produce and store, a male on the other hand can father millions given half a chance so having that chance is of the upmost importance.

Sharks are a frequent visitor of this atoll and as you would imagine, they like it rough. Females have had to develop thicker skin to counter the male’s habit of biting their fins or neck during the act. Despite this, they can still look pretty battered and bruised after a round of mating. Thankfully the ladies can store packets of sperm for as long as a year to avoid having to go through this ordeal too regularly.

The prize of the kinkiest behaviour surely belongs to the Persian Carpet Flatworm (Pseudobiceros bedfordi) which we spotted on a dive recently. As simultaneous hermaphrodites they have the reproductive organs of both sexes, so when they meet with a lover they have to decide who will be male and who the female that day. It’s not an easy decision to make. The two worms fight each other for the privilege of being the boy; each is armed with not one, but two razor sharp penises which are brandished like swords. They dual with their penises until one manages to impale the other, injecting the sperm into any part of the body. The sperm then swims around the body of the victim in search of eggs to fertilize, and so the deed is done. Luckily the worms are capable of rapid repair and can patch up any holes within a day. 

At the other end of the spectrum is the Coral Rabbitfish. Much more romantic than the philandering Parrotfish, they find themselves a life partner when they are only 7cm long. Once in a committed relationship they remain inseparable, growing together, quadrupling their size and mating at the same time each year under the light of the full moon. An elongated snout that resembles puckered lips has helped to strengthen their reputation as a fish in love, a favourite with our honeymooning holidaymakers. 

Romantic Rabbitfish

The House Reef

It cannot be denied that I am a seasoned snorkeler. As a child growing up in the Mediterranean I would run down to the sea every day after school to see how the fish and my beloved octopus were getting on. As a teenager in the Middle East, I would spend months on end in the water. Now, after all this training, I’ve reached the pinnacle of my snorkelling career and gone professional by working as the Resident Marine Biologist and EarthCheck coordinator at Park Hyatt Maldives Hadahaa. This is why, I believe it means something when I judge the Hadahaa house reef to have delivered the best snorkelling I have ever experienced.

The thing that first strikes you about our reef is the sheer volume of coral, a thick tangle of different species, all tussling for space growing one on top of the other, completely obscuring the seabed.  Thousands of brightly coloured reef fish flash in front of your eyes like jewels, going about their daily lives as eager as children in a playground. The coral itself has a pallet of deep browns and greens, which to the untrained eye may seem plain, but for me is heartening. The darker the colour of the coral, the more algae there is living in symbiosis with the polyp. The Algae photosynthesizes, providing nourishment for the coral in exchange for protection. The polyp itself is usually transparent or only slightly tinted, while its skeleton is made of calcium carbonate making it bright white. This means that a coral with light pastel shades is lacking in algae, and the coral on our reef is teaming with the stuff (as much as 30,000 cells per cubic millimetre). 

On a day like today, there is not a cloud in the sky and the sea is so flat it looks like tin foil. The sunlight glides effortlessly through the water and dances on the reef making even the drabbest rock sparkle and glitter. The water is heavy with fish, merrily nibbling away or surveying their domain. A gentle crackling can be heard, reminding you of the amount of activity that goes on unseen below you. I love to watch the electric blue Cleaner Wrasse attending to the larger fish, flittering over their scales and under gills to rid them of dead skin and unwanted parasites. The client hovers in suspended animation with a look of pure ecstasy enjoying their underwater spa treatment, until the Cleaner Wrasse digs too deep, and without warning, is ushered away with a stern flick of the tail. 

A Parrot Fish enjoying his exfoliating spa treatment

For seven months now I have been examining what lives on the reef and what happens subsurface. Sharing the spectacle with our guests and the look of wonder on the faces of first-time snorkelers is hard to beat. Every day I see something new or extraordinary and with any luck the trend will continue for years to come.