12m depth, Isola del Giglio (Italy), Mediterranean Sea, daytime
Another member of the aeolidae – arguably the most beautiful group of snails on the planet. The slugs are only a few centimeters long, which makes them difficult to spot on a busy reef. But once you have developed an eye for them, every dive will be a hunt for these little diamonds of the sea.
25m depth, Giglio (Italy), Mediterranean Sea, nighttime
Opposed to its reef building stony coral relatives, these soft corals do not have photosynthetic partners to supply them with food. Their extended tentacles contain stinging cells which are used to catch small crustaceans, worms and other night-time drifters. Gorgonians are popular with aquarists - but the backdrop in a glass tank will never be as black as in the open ocean.
13m depth, Parque Tairona (Columbia), Caribbean Sea, evening
The colony shape of this common caribbean hardcoral is largely determined by currents and light availability - it can range from spherical balls to flat plates. Safely hidden inside them live single celled algae, fixing carbon for their host. Each coral colony is indeed a large number of organisms living in community, known as holobiont.
20m depth, Isla de Coiba (Panama), Pacific Ocean, daytime
The name of this creature is obviously given by the venomous thorny spikes it is covered in. It lives on shallow reefs throughout the tropics, feeding on corals which it dissolves in the digestive juices of its stomach turned inside-out. During massive population outbreaks documented since the 70s, divers have been encouraged to manually kill them, for example by injecting vinegar.
7-10m depth, Parque Tairona (Columbia), Caribbean Sea, daytime
Growing slow and steady, these are among the most common and long lived reef building corals. The oldest known individuals are about 900 years (!) old and have a diameter of more than 2m. The closeup shows the brainy structure with polyps retracted.
10m depth, Isola del Giglio (Italy), Mediterranean Sea, daytime
Like other aeolid nudibranch species, Flabellina feeds on hydroids – relatives of corals that contain powerful stinging cells. Being a complete specialist for this food, the sea slug can ingest these nematocysts and build them into their own tissue as defense from enemies. Fascinating and beautiful, they are among my favorite creatures underwater.
Isola del Giglio (Italy), Mediterranean Sea, daytime
The underside of an underwater ledge is usually inhabited by completely different animals than the top. Where direct sunlight never hits, filter feeders like these orange and blue sponges can thrive, making a living of pumping reef water through their body. Their hungry hydroid neighbors are meanwhile busy catching anyone who comes too close.
13m depth, Parque Tairona (Columbia), Caribbean Sea, daytime
This crustacean lives in a close relationship with its anemone host. The poisonous tentacles of the anemone protect the shrimp from predators and provide food in the form of trapped animals. The benefit to the host is unclear – maybe he is just invited for his good looks…
13m depth, Parque Tairona (Columbia), Caribbean Sea, daytime
These worms make their home by burrowing into the calcium carbonate skeleton of corals. What looks like a tree is the worms structure for breathing and feeding – it filters microscopic plankton out of the water. When startled by a passing diver, these normally unmoving critters disappear into their burrow in an instant.
12m depth, Curacao, Caribbean Sea, daytime
The red structure is formed by thousands of intertwined filamentous cyanobacteria, each of them thinner than a human hair. Together they can form cohesive mats that cover large parts of reefs in the Caribbean and other tropical seas. These mats are known for the highest recorded natural rates of nitrogen fixation, the same process that is industrially used to make fertilizer.
5m depth, Parque Tairona (Columbia), Caribbean Sea, daytime
The beautiful markings on this snails back are actually made of an living mantle tissue which is covering the snails house. It can be retracted when the snail is attached – and it has apparently lead to a decline in the population at popular dive sites because humans collected the snail thinking the spots are part of the shell.
12m depth, Isola del Giglio (Italy), Mediterranean Sea, daytime
These small sea slugs are among the most beautiful creatures to be found on any dive. Feeding exclusively on sponges, they can often be found in small caves and on overhangs. They incorporate the toxic compounds from their meal into their own body as defense, which is why they can dare to be so brightly colored
5-10m depth, Faial, Azores (Portugal), Atlantic Ocean, daytime
The Remora spends most of his life as a traveller attached to larger ocean dwellers such as sharks, whales, turtles or rays. He gains free food in the form of parasites and faeces from the host while at the same time having its gills flushed with fresh water at all times for breathing with ease. Large fish such as this Eagle ray don’t seem to mind the company at all.
12m depth, Isla de Coiba (Panama), Pacific Ocean, daytime
This Sea star is distributed along the whole pacific coast of south- and central America. Being widely collected and sold as souvenirs in Mexico and Peru, it is now considered close to extinction in these countries. Ironically, the dead shell loses all of its color and comes in a pale shade of brown.
5m depth, Isla de Coiba (Panama), Pacific Ocean, daytime
Identifying fish correctly can be difficult – especially if there are no distinct colors to go by. Whatever the name may be, simply stopping in the shallow water and having a swarm of slivery arrows dart above- below- and all around you is one of the most exhilarating feelings I know.
10m depth, Isla de Coiba (Panama), Pacific Ocean, daytime
Blenniformes describes a large group of small fish that are found in tropical and temperate waters around the world. They like to hide, because the ocean is a dangerous place when you are little. These cheeky ones have made their home in the empty shells of sedentary crabs which, while still alive, have cemented themselves to hard the rock with their forehead.
15-20m depth, Isola del Giglio (Italy), Mediterranean Sea, daytime and nighttime
Like other corals, this sea fan is a colony of polyps that extent their tentacles during the night to catch prey – unsuspecting floating plankton. The body of this horn coral is stiff yet bendable and it is a sought after material for jewelry in some circles. It will newer glow as brilliantly or contrast as crisply when worn around a neck.
5m depth, Isola del Giglio (Italy), Mediterranean Sea, daytime
The direct translation of her latin name is “She of the sea glowing in the night”. This bioluminescent jellyfish can glow in the dark – presumably to attract prey that will swim into its nettled tentacles. It is stunningly beautiful also during the day, especially in front of a backdrop of swarming Mediterranean Damselfish.
5m depth, Faial, Azores (Portugal), Atlantic Ocean, daytime
Known to fellow ocean enthusiasts as the “puppy dogs of the open ocean” these inhabitants of deep waters pose almost no threat to humans. Their slick and elegant movements are accentuated by their friendly smile and trusting eyes. This can best be appreciated after the adrenaline has gone down a little.
3m depth, Pulau Yensawai, Raja Ampat, Indonesia, daytime, freedive
Few things are more mesmerizing than an elegant shoal passing through the water between you and the afternoon sun! These triggerfish belong to the more calm members of their family (others can be quite rowdy) and have a very elegant swimming style. They can change their color depending on their mood, food, and water quality from purple to blue and bluish-green.
25m depth, Pulau Piaynemo, Raja Ampat, Indonesia, daytime, scuba
This cute underwater sea slug is said to resemble a famous Pokemon - probably because of the
distinct orange markings. Quite surely this one does not generate electric shocks…its mantle flaps on the back can be used to protect their sensitive gills – got to be careful when your lungs are sticking out your body.
10m depth, Pulau Kri, Raja Ampat, Indonesia, daytime, scuba
This kind of encounter always makes my heart jump a little – a curious greeting from a little fish that tends to spend the busy time of the day on the inside. The reef can be a dangerous place when you are small…
20m depth, Pulau Piyanemo, Raja Ampat, Indonesia, daytime, scuba
What an explosion of colors! This elegant sea slug is making its way over a field of sponges on one of the most picturesque dive sites I have ever visited. You have to be extra lucky to have buddies with that much air.
1m depth, Pulau Kri, Raja Ampat, Indonesia, daytime, freedive
These giants are probably the most impressive clams in the world – they can weigh up to 200 kg and have an average lifespan of 100 years! Similar to corals, their tissue hosts symbiotic microalgae, which are living in a special circulatory system for ideal access to light – essentially a living photobioreactor.
1m depth, Pulau Kri, Raja Ampat, Indonesia, daytime, freedive
The time around the turning of the year is known as Manta Ray season in Raja Ampat – the large
oceanic travelers are drawn by the currents and rich supply of food. It is the same currents that also bring copious amounts of plastic waste with every single tide...