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  • In the north-east of the Indian Ocean,

  • spanning a latitude of 6 to 16 degrees north of the Equator,

  • lies the Andaman Sea.

  • For the people of Thailand and Burma, also known as Myanmar,

  • the two nations bordering the eastern edge of the Andaman,

  • the sea has always been an integral part of life and the economy.

  • The Andaman's warm waters support an enormity of marine life

  • and they are relied upon for food as well as transport.

  • Limestone formations such as those which make up the Phi Phi Islands

  • contrast with granite outcrops like the Similan Islands.

  • The warm, clear water and diversity of marine life

  • make the Andaman an attractive dive destination

  • and many divers visit each year to explore and enjoy the underwater world.

  • And seldom is the marine landscape as diverse as it is here.

  • Millions of years of decay have cut the limestone pinnacles of Burma's Mergui Archipelago

  • into a terrain of underwater canyons and caves.

  • Further south, the huge granite boulders of Thailand's Similan Islands

  • continue beneath the waterline,

  • creating dramatic caves and swim-throughs.

  • Much of the submerged rock has been colonized by soft corals

  • like this mushroom leather coral at Christmas Point

  • or stony corals like this field of staghorn coral at Koh Bon

  • or this Montipora coral at East of Eden.

  • Elsewhere magnificent anemones have taken over.

  • At shallow sites such as Richelieu Rock the ebb and flow of the tide

  • brings the oxygen necessary for turtle weed, a type of green algae, to flourish.

  • Dendronephthya soft corals adorn the valleys and slopes at Hin Muang, or "purple rock" in Thai.

  • Elsewhere pretty crinoids, or "feather stars",

  • take up prime positions for filtering plankton from the water.

  • A feeding strategy shared by giant sea fans,

  • whose sieve-like skeleton makes them highly efficient filter feeders.

  • Here between the rocks and coral lie leopard sharks.

  • These gentle creatures are quite the opposite of many people's impression of the fearsome shark.

  • Rather than sharp teeth, their mouths contain ridged plates.

  • Leopard sharks can be easily and safely approached

  • but if divers get too close they will finally make their departure.

  • Although "leopard shark" is the most commonly used name in the Andaman Sea,

  • globally, these sharks are more commonly known as "zebra sharks",

  • because the rarely seen juveniles have stripes, not spots.

  • Bearing many similarities to leopard sharks,

  • nurse sharks are also normally placid.

  • Like leopard sharks they don't have sharp teeth.

  • Nurse sharks should be treated with respect however.

  • They have been known to bite divers when provoked,

  • and if they bite they tend not to let go.

  • During the day, tawny nurse sharks are normally found sleeping under ledges,

  • often piled up in groups like here at Koh Bon Pinnacle.

  • Although nurse sharks generally feed at night,

  • here at the Burma Banks they are often on the prowl looking for food during the day time too.

  • They have 2 barbels above the mouth which help them probe for food.

  • When the shark senses prey such as small fishes or crustaceans

  • it uses a strong sucking action to draw the food into the mouth.

  • Bonds between nurse sharks appear to be closer than with many other shark species

  • and they are often seen swimming in couples.

  • At Thailand's Richelieu Rock, a whale shark makes a rare appearance.

  • This is no whale but rather the world's largest fish.

  • Whale sharks can grow up to 12 meters long,

  • although unconfirmed reports circulate of giants up to 18 meters long.

  • This female is about the average size of 8 meters.

  • There is little to match the awe inspired by an encounter with a whale shark,

  • and for many divers this is the pinnacle of their underwater experience.

  • Their 3000 tiny teeth are rarely used.

  • When feeding they hold their mouths open

  • and feed on plankton, fish eggs and small marine creatures.

  • Ridges down the whale shark's back are reminiscent of those on zebra sharks' backs

  • and like the zebra shark, the whale shark poses little danger to humans.

  • She has lost the top part of her tail,

  • perhaps due to an attack by a predatory shark when she was a youngster,

  • or possibly a collision with a boat's propeller.

  • The shark's fins act like rudders,

  • helping steer it gracefully through the water.

  • For a long time whale sharks were thought to be oviparous,

  • in other words hatching from eggs laid by the mother.

  • However since 1995,

  • females have been discovered containing hundreds of hatched pups,

  • proving that the young complete their development inside the mother's body before birth.

  • As is typical of large pelagic fishes, the back is darker than the belly.

  • This countershading helps it blend in with its environment,

  • and the abstract pattern of spots and stripes on the back enhances the camouflage from above.

  • Some whale sharks attract shoals of fish around the head,

  • such as these juvenile scad,

  • protecting themselves from predators which may be intimidated by the shark.

  • The shark itself does not prey on them,

  • and they are careful enough to cruise in front of its cavernous mouth,

  • without getting sucked in.

  • This much younger whale shark approached boats near Western Rocky Island

  • and stayed around for a long time.

  • Although it might be tempting to touch or even hitch a ride on a whale shark,

  • this practise is highly discouraged.

  • It may modify the shark's natural behavior, or even cause infection.

  • It can also be dangerous for the diver or snorkeler.

  • Despite their usual graceful and stately motion,

  • whale sharks can draw on great strength if they become agitated,

  • and should be respected like any wild animal.

  • Shark fin soup is seen as a delicacy and status symbol in many Asian markets.

  • A single whale shark fin can fetch tens of thousands of dollars in some Chinese restaurants,

  • and often a whale shark fin is not eaten

  • but just used to advertise the availability of shark fin or shark fin soup.

  • Whale sharks do not reach sexual maturity until they are 25 years old,

  • and pregnancies are few and far between,

  • so their survival is particularly at risk.

  • Unless this culture changes,

  • or legislation is introduced and enforced,

  • whale sharks, like many other sharks,

  • may soon disappear forever.

  • From the shadows, and shoals of cardinalfish

  • at Burma's Shark Cave,

  • a grey reef shark emerges.

  • This strong stocky shark feeds mainly at night,

  • but may sometimes be seen cruising during the day.

  • The canyon at Shark Cave provides an excellent viewing gallery.

  • Although grey reef sharks can sometimes show aggression in their behaviour,

  • this is extremely rare amongst those found in the Andaman.

  • A visit to the Burma Banks will sometimes yield an interesting encounter with silvertip sharks.

  • These juveniles are particularly curious of divers.

  • As adults they will grow larger than grey reef sharks,

  • up to 3 meters in fact,

  • but they will also withdraw slightly

  • and become more wary of close human contact.

  • Already these young silvertips display the streamlined body and attractive coloration

  • that make them a favorite amongst shark lovers.

  • One of the most common sharks to be found across the Andaman Sea

  • is the whitetip reef shark.

  • Because of similar coloration of the dorsal and tail fins,

  • the whitetip reef shark and silvertip shark are sometimes confused,

  • but the whitetip has a wedge-shaped head,

  • and it's cigar-shaped body is slimmer than the silvertip's.

  • Black Rock, on the western edge of the Mergui Archipelago,

  • is one of the area's best dive sites,

  • and whitetip reef sharks are commonly encountered during the descent.

  • The other main order of cartilaginous fishes to be found

  • around the Andaman's reefs is the rays,

  • and most common of these is the bluespotted stingray.

  • This stingray's coloration and common name

  • make it often confused with the more circular blue-spotted stingray

  • found in the Gulf of Thailand,

  • which belongs to a different genus.

  • The bluespotted stingray is found on sandy bottoms

  • at sites such as East of Eden in the Similans.

  • The neutral color of the larger Jenkins whipray

  • camouflages it well against the seabed.

  • This ray has a pair of sharp and venomous spines near the base of its tail,

  • and the name "whipray" comes from the ray's ability to whip it's long tail over fast

  • and administer a nasty sting to a predator at any part of its circumference.

  • The ray takes water in through its spiracle, a hole just behind the eye.

  • This water can be blown out through the mouth

  • to excavate food from the substrate.

  • Another large stingray common to the area is the blotched fantail ray.

  • This impressive species can grow nearly 2 meters in diameter

  • and is often one of the highlights of dives in the Andaman.

  • Blotched fantail rays are most impressive when they aggregate in shoals.

  • Occasionally they can be witnessed in large numbers.

  • I encountered this shoal of some 30 individuals at Black Rock.

  • They had possibly gathered to mate.

  • Another visitor to Black Rock and other deep-water sites is the spotted eagle ray.

  • In some parts of the world eagle rays stay together in schools.

  • In the Andaman Sea they are normally found alone.

  • Just behind the short dorsal fin they have up to 6 venomous tail spines

  • which can inflict serious damage on attackers.

  • Between its wing-like fins it has a solid, heavy body and a deep head.

  • The smoothtail mobula is a similar size to the eagle ray

  • but can only usually be seen by divers in the northern Andaman

  • at sites like Burma's Tower Rock,

  • although they are occasionally seen in Thailand

  • at sites such as Racha Noi.

  • The mobula is a member of a group termed "devil rays",

  • so named because of 2 protruding cephalic fins either side of it's mouth.

  • These fins help to direct plankton and small marine creatures

  • into the mouth for feeding.

  • The mobula is a highly social fish

  • and is often observed in large schools.

  • The mobula is an impressive sight

  • but shares our seas with a much larger devil ray:

  • the king of all rays, the giant manta ray.

  • Mantas are frequent visitors to sites such as Koh Bon.

  • Giant mantas can grow to a width of over 6 meters

  • and a weight of over 2 tonnes.

  • These pelagic fish are always on the move

  • and like mobulas, they feed by swimming open-mouthed

  • and using the 2 cephalic fins to direct water into the mouth.

  • The gills on its white underside contain rakers

  • which filter out plankton and small organisms.

  • The markings on the back and underside of mantas are highly variable

  • and are useful in distinguishing individuals.

  • Occasionally the cephalic fins are furled up into cylinders to improve streamlining.

  • Mantas are one of the most intelligent fish,

  • with the largest brain-to-body mass ratio of all elasmobranchs.

  • They often seem to enjoy interaction with humans.

  • A gentle approach by divers is often permitted,

  • and mantas will sometimes approach divers,

  • apparently out of curiosity.

  • Mantas only give birth to an average of two pups every two years,

  • and populations have long been in decline.

  • The gill rakers of mantas and mobulas are used in a Chinese medicine

  • that is thought to detoxify the blood.

  • There is no scientific evidence that it works.

  • Nevertheless the lucrative trade is on the increase.

  • In November 2011

  • the International Union for Conservation of Nature

  • declared giant manta rays as "vulnerable with an elevated risk of extinction".

  • Down on the reef, a fish trap has caught a handful of bony fishes

  • including a giant moray eel.

  • This is the largest of all morays.

  • Despite their fearsome appearance,

  • morays are not as dangerous to humans as they look,

  • although larger morays can attack if provoked

  • and have been known to bite divers when being fed.

  • The mouth contains sharp teeth for capturing and restraining prey.

  • Once captured, a second set of jaws in the throat

  • is launched forward to grab the prey

  • and pull it down the moray's gullet.

  • Anemone Reef is home to several specimens of yellow-edged moray.

  • Like many morays they feed on small reef fishes.

  • Khao Lak's Boonsung tin miner wreck

  • has a particular concentration of honeycomb morays.

  • This spotted moray at the Burma Banks is a close relative.

  • Whitemouth morays are not at all common in the Andaman.

  • This rare specimen was seen at Burma's Western Rocky Island.

  • Another Myanmar speciality is the barredfin moray.

  • When feeling threatened it adopts a very snake-like posture.

  • Facial injuries are quite common amongst morays,

  • and this palechin moray at High Rock bears the scars of past conflicts.

  • The cartoon-like features of the greyface moray

  • are much more common throughout the area

  • and these eels are often found in pairs or small groups.

  • This is a small and very energetic species

  • and when it attacks it moves quickly.

  • Greyface morays don't just live with each other;

  • they often share their home with other species.

  • In this case a fimbriated moray.

  • And here we find a fimbriated moray with a snowflake moray.

  • Whereas the previous species feed mainly on fishes,

  • the snowflake moray feeds on shelled molluscs and crustaceans,

  • so it's teeth are much more blunt.

  • It's not difficult to see how the zebra moray got its name.

  • This moray also feeds on crustaceans.

  • Of all the marine creatures found in the Andaman Sea,

  • possibly the tiger tail seahorse carries the most mystique.

  • The seahorse finds a suitable holdfast,

  • such as this black sun coral,

  • and anchors itself to it using its striped tail.

  • Here at Shark Cave a seahorse has become stuck to a worm sea cucumber.

  • The seahorse struggled for several minutes

  • before finally freeing itself from the sea cucumber's adhesive body.

  • Perhaps the most interesting fact about the seahorse

  • is that it is the male of the species that becomes pregnant.

  • The gestating fetuses are carried in a pouch on the seahorse's belly.

  • Typically, litters comprise 100 or more perfectly formed babies,

  • each just a few millimeters in length.

  • Seahorses are generally monogamous,

  • and it is not uncommon for the male to become pregnant

  • several times per year with the same female mate.

  • The bluespotted cornetfish, sometimes known as the "smooth flutemouth",

  • is seen hunting for small fishes here in the canyon at Shark Cave.

  • Its slim profile is both streamlined for high speed,

  • and minimizes the chances of it being seen as it approaches prey.

  • The long thin snout bears a resemblance to its seahorse cousins.

  • Staghorn coral is found in abundance on the east side of Racha Yai island,

  • and this hard coral is one of the favored habitats of the trumpetfish.

  • It's elongated body gives it a much larger turning circle than fellow reef fishes.

  • Amongst coral the trumpetfish often has to make three-point turns,

  • relying on it's tiny pectoral fins to reverse out of a corner,

  • before propelling itself forward again.

  • The trumpetfish's dorsal and anal fins are right back on its tail

  • and give it a great turn of speed when attacking prey.

  • The bright yellow variant of the trumpetfish

  • can sometimes be spotted in the Similan and Surin islands.

  • A visit to the island of Koh Tachai

  • often provides a special treat for divers:

  • a large and easily approached school of teira batfish.

  • The underwater landscape here is characterized by large granite boulders

  • which provide the type of shelter that the batfish love.

  • Hanging in the current, sometimes on their side,

  • the batfish are very easily approached.

  • Batfish take their name from their elongated pair of pelvic fins.

  • Other varieties in the area include the pinnate batfish,

  • seen here at Koh Bon

  • And the similar golden spadefish,

  • seen here in a school at Koh Torinla in the Surin Islands.

  • This batfish's tall proportions mark it out to be a juvenile.

  • Very young batfish can be 3 times as tall as they are long.

  • This striking design belongs to a young emperor angelfish.

  • In adolescence, angelfish undergo a dramatic metamorphosis.

  • The adult's masked face and striped body are nothing like the young.

  • The entirely different appearance of the juveniles

  • is thought to protect them from adults of the same species,

  • which otherwise might attack them to protect their territory.

  • The distinctive blue ring angelfish can be seen on many Andaman dive sites

  • individually or in pairs.

  • The Similan Islands also host regal angelfish

  • and blueface angelfish.

  • This individual from Boulder City bears deep scars

  • and trails fishing line from its mouth.

  • Butterflyfish brighten up any reef

  • and there are many species in the Indian Ocean.

  • This is a pair of copperband butterflyfish at Anemone Reef.

  • and these are Meyer's butterflyfish in the Similans,

  • often found mixed with black pyramid butterflyfish.

  • The raccoon butterflyfish is one of the most distinctive species.

  • They are often mixed with redtail butterflyfish,

  • the most common member of the family in the area.

  • Bannerfishes are common throughout the area

  • and are characterized by a very long spine at the front of the dorsal fin.

  • Schooling bannerfish can be seen in shoals close to the reef

  • or hanging above it feeding on zooplankton.

  • At first glance the moorish idol may be mistaken for a bannerfish.

  • It bears similar form and coloration,

  • but belongs to a totally different family.

  • Nevertheless they show similar habits.

  • Like the bannerfish they can be seen alone or in large schools.

  • These sailfin tang are feeding on algae covering the boulders at Rocky Point.

  • Powder blue tang are seen at most sites within the Similans.

  • "Tang" are also known as "surgeonfish",

  • so named because of the razor sharp spines just in front of the tail

  • which can be used during combat.

  • The tail spines of unicornfishes are particularly prominent.

  • The ringtailed unicornfish also bears the spike on its head

  • that gave the genus it's name.

  • This common reef fish is appropriately named the "crescent-tail bigeye".

  • Bigeyes typically inhabit dark spaces such as caves,

  • where the large eyes help them see in low light.

  • They occasionally form small aggregations like this one at Rocky Point.

  • In open water their skin color adapts to the bright conditions

  • by becoming paler,

  • thereby making it less conspicuous.

  • The juvenile emperor red snapper

  • is one of the most distinctive of all reef fishes,

  • but rarely seen.

  • Named after the sea itself,

  • the boldly spotted Andaman sweetlips has a striking design.

  • But perhaps the most photogenic of all our reef fishes is the oriental sweetlips.

  • Although often found alone, this species is at its most striking in numbers.

  • Schools can be encountered among the enormous granite boulders

  • at Christmas Point and Elephant Head Rock in the Similan Islands.

  • The Andaman Sea is home to a large variety of groupers.

  • Smaller species such as this blacktip grouper

  • or the slightly larger longfin grouper

  • look nervous when approached,

  • but show little effort to make an escape

  • in comparison to many larger species.

  • One of the biggest bony fishes in our area is the brown-marbled grouper.

  • Individuals of over 1m in length

  • are often observed at Richelieu Rock.

  • This disused and broken fish trap

  • provides temporary protection

  • for one particularly large individual.

  • The potato grouper, or potato "cod", grows even larger.

  • Encounters in the Andaman are a rarity,

  • but Silvertip bank is home to one particularly tame

  • and curious individual nicknamed "Freddie".

  • When visiting divers feed sharks here,

  • Freddie invariably shows up to get a piece of the action.

  • The expectancy of food is undoubtedly his main motive for approaching divers,

  • but he does seem to enjoy contact with humans.

  • On a similar scale to the potato cod is the humphead wrasse:

  • the largest of all wrasses.

  • The species can grow up to 2 meters

  • and as it matures it develops a protruding hump on its forehead.

  • This individual was seen at Shark Fin Reef.

  • Another speciality of Shark Fin Reef, and nearby Boulder City,

  • is the humphead parrotfish.

  • The protruding lump of bone on the forehead

  • is used for head-butting rivals during combat.

  • The teeth are fused together into a parrot-like beak

  • which is strong enough to bite through even the hardest corals.

  • Several species of barracuda inhabit the Andaman.

  • Unlike other species, the great barracuda prefers to stay alone

  • or in loose associations with other individuals.

  • Here at Silvertip Bank, one or two great barracudas

  • are commonly found around the mooring line.

  • The barracuda possesses enormous speed and a razor sharp set of teeth

  • which makes it one of the reef's top level predators.

  • The barracuda preys on small fishes

  • and on occasions shiny jewellery worn by divers has been mistaken as prey,

  • with unfortunate results for the diver.

  • This giant trevally is another very fast predator.

  • Trevallies are often referred to as "jacks",

  • and like the great barracuda, they prey on small fishes.

  • These are bluefin trevallies,

  • thriving on the currents around the giant boulders at Rocky Point.

  • And these are young golden trevallies

  • in the depths at Richelieu Rock.

  • Back down on the reef,

  • we find the most common of the pufferfish family,

  • the blackspotted puffer.

  • At Black Rock these fish can often be seen just resting on the bottom,

  • or in this case amongst the branches of a sea fan.

  • This larger species is a map puffer.

  • Like parrotfish, puffers' teeth are fused together to form a very strong beak.

  • This is a blue-spotted puffer,

  • although this particular individual is lacking

  • the characteristic blue coloration around the face.

  • Like other pufferfish,

  • if it feels greatly threatened it will swallow water

  • to inflate its body into a ball

  • in order to appear more intimidating.

  • The largest of all pufferfish is the starry puffer.

  • They are fairly unfazed by the close attentions of divers.

  • The yellow boxfish's body is covered with hexagonal bony plates,

  • fused together into a rigid carapace for protection.

  • This fish releases toxins if stressed,

  • and the bright coloration serves as a warning to would-be predators.

  • Nevertheless, this juvenile gets a nip from an aggressive damselfish

  • and retreats to the shelter of the reef.

  • As the yellow boxfish matures

  • its bright yellow coloration darkens and fades,

  • and it gains more white spots amongst the black ones.

  • Large adults take on an altogether more purple hue.

  • The male whitespotted boxfish has a very distinct coloration.

  • The female of the species is a uniform black with white spots.

  • On Khao Lak's Boonsung wreck we find a tiny horn-nosed boxfish.

  • In adulthood the species develops a prominent bump on its snout.

  • The porcupinefish is covered with spines

  • which normally lie flat against its body.

  • When under threat, they can inflate their bodies with water, like pufferfish.

  • When doing so, the spines, point straight out as a defense.

  • This spot-fin porcupinefish has broken some of its spines,

  • presumably by reversing out of a hole.

  • The damaged spines will soon grow back.

  • As can be seen from this black-blotched porcupinefish,

  • their eyes are quite vulnerable to attack or self-inflicted damage

  • and it's quite common to see individuals that have been blinded in one eye.

  • It's diet includes bivalve molluscs,

  • and the porcupinefish has a strong bite

  • when exploring the reef for such food.

  • The smaller long-spine porcupinefish

  • is occasionally seen foraging on the seabed surrounding the reef.

  • Scrawled filefish, sometimes referred to as "leatherjackets",

  • are characterized by a long snout and tail fin,

  • and a long, slender dorsal spine.

  • Triggerfishes, such as this orange-lined triggerfish, are close relatives.

  • Of all the marine creatures in our area,

  • one of the most striking is the clown triggerfish.

  • Like filefishes, triggerfishes have a pronounced dorsal spine

  • or "trigger" that they will raise when under threat.

  • Unlike the larger varieties of the family,

  • redtooth triggerfish are sometimes seen in large shoals

  • like here at Silvertip Bank.

  • The yellowmargin triggerfish is equipped with a very strong bite.

  • The largest of all triggerfishes is the titan triggerfish.

  • This is a highly territorial species

  • and aggressively defends its nest against intruders and bypassers.

  • Here at East of Eden a painted spiny lobster is out in the open,

  • but soon retreats under its ledge when approached.

  • Spiny lobsters lack the claws that other lobsters possess,

  • but they have very long barbed antennae,

  • their main sensory device.

  • The whole of the front part of the lobster's body

  • is covered in an array of spines and blades:

  • a formidable defense against any attacker.

  • The amazing colors of the ornate spiny lobster

  • are not common in the Andaman,

  • but one spot where they can be found is Black Rock.

  • The tunnel through the middle of Western Rocky Island

  • is dominated by longlegged spiny lobsters.

  • Dozens of them inhabit the cracks and crevices of the cave's walls.

  • Decapods come in a wide range of sizes.

  • These tiny rock cleaner shrimps inhabit the dark hollows at Richelieu Rock.

  • Burma's Moving Wall was given its name

  • because of the masses of Durban hinge-beak shrimps living there.

  • They are characterized by large bulging eyes

  • and a body that hinges in the middle

  • to facilitate molting of the shell.

  • Banded coral shrimps have much longer claws and are always found in pairs.

  • Now for an entirely different type of crustacean, the swimming crab.

  • The swimming crab's 5th pair of legs, its hindmost,

  • are flattened into paddles which enable it to swim.

  • This red-legged swimming crab was found in deep water

  • and well away from the reef.

  • This is a territorial crab and this individual got very agitated

  • when it presumably mistook its reflection in the camera lens for a real rival.

  • Cowries are amongst the most eye-catching molluscs

  • that adorn the area's reefs.

  • This richly colored variety is a mole cowrie.

  • The shell is kept shiny by a bilobed mantle

  • which gradually extends across the shell

  • as the cowrie creeps along the reef.

  • The shells of various cowrie species are used as jewellery

  • and in some primitive cultures indicate the rank of the wearer.

  • Some shells have even been used historically as money.

  • Traditionally cowrie shells have been sought after by collectors

  • due to their highly glossy finish

  • and the huge variety of colors.

  • This species is the tiger cowrie,

  • one of the largest and most common.

  • The fully extended mantle exhibits branching papillae,

  • seen here with a juvenile hinge-beak shrimp in the vicinity.

  • This Arabian cowrie at Moving Wall

  • slithers past the spines of a sea urchin

  • and into the shelter of the rocks.

  • Some of the prettiest marine creatures are also some of the smallest.

  • Like cowries, sea slugs are found in a huge variety of colors.

  • Worldwide there are more than 3000 species.

  • They are blind, so they touch, taste and smell

  • with two antenna-like organs on the head

  • known as rhinophores.

  • Many of the most colorful varieties of sea slug are nudibranchs.

  • The word "nudibranch" means "naked gills",

  • referring to the branchial plume on their back

  • through which they breathe.

  • Many nudibranchs feed on stinging creatures

  • such as corals and hydroids.

  • Aeolid nudibranchs have the ability to store their prey's sting

  • in the cerata on their back,

  • and later discharge it in their own defense.

  • Risbecia nudibranchs often exhibit "trailing" behavior,

  • whereby they follow each other "top-to-tail".

  • It's thought this might ensure they can easily find each other

  • when they are ready to mate.

  • Nudibranchs lay their eggs in a ribbon stuck to the reef.

  • Like their bearers,

  • the egg masses vary greatly in form and color,

  • and are often poisonous.

  • Phyllidiid nudibranchs lack the external gill plumes of other families.

  • Their gills are under the skirt of the mantle.

  • The mantle itself is covered with hard tubercles.

  • The coloration of ocellate Phyllidia always varies

  • around a palette of gold, black and white.

  • This is a very common combination of warning colors,

  • and advertises the slug's unpalatability.

  • The varicose Phyllidia has no known predators.

  • If stressed, it releases a strong toxin.

  • At the other end of the scale in the category of molluscs

  • is the fluted giant clam,

  • which burrows its hinge into the reef. (at a shallow depth).

  • Giant clams are bivalves.

  • They siphon water through 2 holes,

  • extracting oxygen and plankton

  • for respiration and feeding.

  • Giant clams are often host to smaller marine creatures.

  • This small swimming crab finds shelter inside the clam's shell,

  • as does this young spotfin lionfish.

  • In 2003 the Thailand authorities deliberately sank a Chinese fishing vessel

  • off Similan Island number five in order to create an artificial reef.

  • The wreck later became commonly known as the "tuna wreck".

  • Just a few months after the sinking,

  • the wreck had already become home to quite a variety of marine life.

  • In particular, shoals of tiny cardinalfish

  • were already swarming in and around the wheelhouse.

  • Cardinalfish also find shelter in this small wreck on Racha Yai's Home Run.

  • Many of the Andaman's natural reefs

  • are similarly cloaked in shoals of tiny fish.

  • These luminous cardinalfish shelter amongst black sun corals.

  • Here at Koh Bida Nai the whole reef appears to sway with life.

  • While a social aggregation of fishes is known as a "shoal",

  • when they are more tightly organized and swim with coordinated movements,

  • they are known as a "school".

  • The tendency of fishes to form schools is a natural defense mechanism.

  • Each fish instinctively follows its neighbours' movements very closely,

  • and the resulting congregation can be confusing for predators.

  • The sheer number of eyes in a large school

  • makes it easier for the fish to spot predators.

  • It's all about strength in numbers.

  • Schooling fishes tend to choose other fishes of similar size and appearance,

  • but not always the same species.

  • If a fish stands out, it is more likely to be targeted.

  • This African pompano at Shark Cave made some half-hearted attempts

  • at catching the schools of fusilier and young barracuda.

  • On this occasion it left empty-mouthed.

  • Striped eel catfish such as these at Lucy's Reef

  • are invariably found in schools.

  • They forage for food in the day,

  • but are seen here resting at night.

  • Bigeye snappers can be seen schooling at Hin Muang.

  • Enormous schools of these fish are a feature of many reefs.

  • Bluestripe snappers form slightly smaller schools,

  • as do their cousins, two-spot banded snappers.

  • Variable-lined fusiliers, a common sight in the Similans,

  • often gather in their thousands,

  • and more often than not they're all swimming in the same direction.

  • The Andaman Sea is home to several species of schooling barracuda.

  • Large schools of bigeye barracuda are common at more inshore sites

  • such as the Racha Islands.

  • At Black Rock the larger pickhandle barracuda,

  • with it's distinctive yellow tail, is a common sight.

  • At Koh Tachai and Richelieu Rock you are more likely to find blackfin barracuda.

  • In the Mergui Archipelago, the similar but smaller sawtooth barracuda is more common.

  • At Western Rocky Island the school sometimes forms a huge vortex.

  • Like barracuda, dogtooth tuna prefer to socialize and hunt in numbers.

  • Of the trevally family, it's most likely bigeye trevallies

  • that form large schools in their search for small reef fishes.

  • Again, isolated outcrops such as Richelieu Rock and Black Rock

  • provide the upwellings and currents that the trevally favor.

  • While forming schools can provide a degree of protection for some fishes,

  • others will take a more direct approach to survival.

  • In the depths of the Mergui Archipelago,

  • pastel tilefish use their mouths to build enormous mounds of dead coral.

  • When approached, the fish literally dive head-first into the rubble.

  • This rare and highly pregnant dwarf whipray near the Boonsung wreck

  • is well disguised against the sand.

  • When the ray is threatened,

  • a quick shuffle can make it almost disappear from view.

  • Bluespotted stingrays occasionally hide in a similar manner.

  • Together with the sting on their tail, and their considerable speed,

  • they have the tools they need to avoid attack.

  • If the natural camouflage of the day octopus fails it,

  • then it has another defensive weapon up its sleeve.

  • Mimicry is another common defensive strategy.

  • The straightstick pipefish, a relative of the seahorse,

  • resembles a sea whip waving in the current,

  • and hence remains largely unnoticed by predators.

  • This is known as "passive camouflage".

  • This ornate ghost pipefish hangs head downwards,

  • mimicking the sea fan behind it.

  • The ghost pipefish is even able to change its body coloration

  • to blend in perfectly with the environment.

  • This juvenile cheeklined wrasse blends in perfectly with the sea fan behind it.

  • At first sight the giant frogfish resembles a sponge.

  • It actually walks around the reef using its fins which have evolved into legs.

  • The skin coloration is adjusted to suit the surroundings.

  • Frogfishes are a type of anglerfish,

  • and have a very cunning technique for finding food.

  • Their slender dorsal spine, the illicium,

  • is waved around like a tiny fishing rod.

  • Tasty bypassers attracted to the lure at the end of the illicium

  • are engulfed by the huge mouth in a fraction of a second.

  • Frogfishes sometimes use the same movement as a threat display

  • when they have been detected.

  • The bearded scorpionfish also opens its mouth in a show of aggression

  • if it is recognized or if it enters into a territorial dispute.

  • The bearded scorpionfish is a master of disguise.

  • It is an ambush predator,

  • and changes its color to blend in with the surrounding environment,

  • making it almost invisible to its prey.

  • Besides the camouflage, scorpionfishes have a formidable armoury

  • of stinging spines along their fins for defense.

  • The devil scorpionfish, sometimes known as a "false stonefish",

  • camouflages itself in the same manner.

  • Its skin is incredibly adaptable in color and texture.

  • But if it's disturbed enough the brightly-colored underside

  • of its pectoral fins can help deter attackers.

  • The stonefish possesses an unparalleled combination of disguise and toxicity.

  • Its spines contain some of the deadliest venom of any fish,

  • and it lies motionless, resembling a rock, waiting to attack.

  • Here on the Boonsung wreck a honeycomb moray barges past a stonefish

  • that it appears not to notice.

  • The stonefish's strategy when not pouncing on prey is simply to "play dead".

  • Large morays have been known to prey on stonefish.

  • In 1997 the King Cruiser, a passenger ferry,

  • sank between Phuket and Phi Phi Island,

  • creating a brand new artificial reef

  • and a highly popular dive site.

  • In the intervening years she has become home to great numbers

  • of another member of the scorpionfish family, the red lionfish.

  • Unlike it's camouflaged cousins, the lionfish makes little attempt to hide.

  • Instead it flares out its fins when approached,

  • revealing an impressive array of stinging spines

  • that would deter even the boldest of predators.

  • It's possible that some of these fish are a very similar species

  • commonly known as "devil firefish",

  • whose distribution overlaps that of the red lionfish.

  • Lionfish sometimes form small communities such as here at Richelieu Rock

  • where as many as ten can be found resting together.

  • The distinctive pectoral fins of the zebra lionfish

  • are a delight for underwater photographers but a deterrent to predators.

  • Richelieu Rock hosts a small community

  • of a slightly different different species,

  • commonly known as the "frillfin turkeyfish".

  • The spotfin lionfish is a more common sight.

  • Its fins are almost completely transparent.

  • The spines of the crown-of-thorns starfish

  • contain a neurotoxin intended to cause paralysis.

  • They feed on stony corals

  • and human intervention has been required in some parts of the world

  • where these starfish threatened to destroy entire reef systems.

  • The sea urchin's spines are not nearly so dangerous to humans

  • but they are barbed and very fragile

  • and the ends of the spines are designed to break off

  • and remain in the flesh of any attacker.

  • Between the spines, the sea urchin has a bulb-like anal cone

  • through which it expels its feces.

  • Some cardinalfishes are small and careful enough

  • to hide amongst the spines of the crown of thorns starfish or the sea urchin,

  • thereby using the defense of the host to protect themselves.

  • This is known as a "commensal" relationship,

  • whereby one partner in the relationship benefits

  • while the other receives neither benefit nor harm.

  • It's a similar strategy adopted by anemonefishes.

  • They make their home in sea anemones,

  • the perfect refuge from predators.

  • Their skin has a special immunity from the anemone's stinging tentacles.

  • Skunk clownfish tend to favor the magnificent sea anemone.

  • Clark's anemonefish are not so particular

  • and find their home amongst a number of species of sea anemone.

  • This is a mutually-beneficial relationship.

  • While the fish are protected,

  • their feces provide food for the anemone

  • and they help keep it free of parasites.

  • They also chase away polyp eaters such as butterflyfishes,

  • thereby defending the anemone as well as their own family.

  • Some even attempt to chase off passing divers.

  • Juvenile Clark's anemonefish are predominantly orange in color.

  • Saddle anemonefish are not so prevalent

  • and are commonly associated with bubble-tip anemones

  • such as here at Richelieu Rock.

  • Juveniles display a white stripe reminiscent of other adult species.

  • Anyone who has seen the film "Finding Nemo"

  • will already be familiar with ocellaris clownfish.

  • They are normally found living amongst magnificent sea anemones.

  • Typically an anemone hosts a dominant female matriarch and her male mate,

  • as well as one or more juvenile anemonefish.

  • When the female dies, the male transforms into a female

  • and the highest ranking adolescent is promoted to be her mate.

  • Due to abnormally warm conditions,

  • this anemone has lost the symbiotic zooxanthellae that give it its color,

  • and may or may not recover.

  • Other types of fish have also evolved a resistance to the sea anemone's sting.

  • Juvenile domino damsels are often seen around sea anemones.

  • Competition with anemonefishes, as well as with each other,

  • can be fierce and incessant.

  • As adults they are one of the most aggressive fish on the reef, for their size,

  • and become less reliant on anemones for protection.

  • Another creature that uses the anemone to protect itself

  • is the porcelain anemone crab.

  • At the end of the crab's third maxillipeds

  • is a fan of bristles known as "setae"

  • which the crab holds against the current to filter plankton from the water.

  • Any collected food is scraped into the mouth

  • by smaller setae on the innermost maxillipeds.

  • Tube anemones are often seen in isolation on the seabed.

  • This tube anemone's stinging tentacles provide protection for a magnificent shrimp,

  • as well phoronid worms which cover the tube.

  • A pair of whitecheek monocle bream pass by.

  • Jellyfishes, of course, are well known for their sting

  • and often attract hitchhikers such as small sardines.

  • The small fishes remain in the vicinity of the jellyfish,

  • sometimes for their whole lives.

  • When attacked, they find protection under the jellyfish's bell

  • or even right inside, past its stinging tentacles.

  • These hitchhikers are sheltering in a crowned jellyfish.

  • And this rhizostome jellyfish is harboring juvenile scad.

  • Older scad change from hunted to hunter.

  • The jellyfish's sting is no guarantee of its own survival.

  • This Australian spotted jellyfish at Racha Yai

  • comes under attack from a scrawled filefish.

  • Once a jellyfish has lost its defenses, a free-for-all invariably ensues.

  • Rainbow runners dart by,

  • but this feeding frenzy like many others is led by streaked spinefoots.

  • Although the opportunistic spinefoots have a taste for jellyfishes,

  • they are normally herbivores.

  • Here they join a shoal of Singapore parrotfish in search of food.

  • The top of the reef is covered in a layer of nutritious algae

  • which the marauders devour en masse.

  • Here at East of Eden bluefin trevally team up with goldsaddle goatfish

  • to hunt the reef for small fishes.

  • Smalltooth emperors join the gang too.

  • The emperors' skin takes on dark blotches while feeding,

  • but soon fades to a neutral color when the fish resume swimming.

  • At Racha Noi this school of mullet makes an impressive sight.

  • In rapid time the fish scoops a mouthful of sand from the seabed,

  • filters out edible organic matter, and then spits out the unwanted sand.

  • The defensive tactics of titan triggerfish when protecting their nest

  • have won the respect of many divers.

  • When feeding they can be an impressive sight too,

  • their powerful jaws enabling them to tackle even large chunks of stony coral.

  • On the wonderful plateau south of Koh Tachai

  • this triggerfish's feeding has attracted an array of hangers-on

  • that would do any aquarium proud.

  • Everything from tangs to moorish idols joins the throng,

  • hoping to pick up some of the triggerfish's scraps

  • or find some food for themselves.

  • The discovery of this broken mussel at Anemone Reef

  • has sparked another feeding frenzy

  • and a similar variety of reef fishes get involved in the scrap.

  • Blackspotted puffers often stand by at such gatherings.

  • Their lack of agility and awkward shape

  • put them at a disadvantage to other fishes.

  • Here at Richelieu Rock, however, this blackspotted puffer has less competition

  • and pecks away at the base of a small anemone while avoiding its sting.

  • The pufferfish retracts it's lips as it bites

  • so only its bony beak makes contact.

  • Trumpetfish often ride above a larger host such as this porcupinefish,

  • allowing them to sneak up on small prey such as damselfishes

  • that are not preyed upon by the larger host itself.

  • Trumpetfish sometimes craftily conceal themselves within a school of fish

  • such as these yellowfin goatfish.

  • The trumpetfish is much faster than the goatfish

  • and can lunge out of the school to catch unsuspecting prey.

  • Banded sea kraits are one of the most venomous creatures on the planet,

  • but they are little danger to divers.

  • Their mouths are tiny

  • and while underwater they are prepossessed with hunting

  • for their natural prey of eels and fishes.

  • The tail has evolved into a flat paddle

  • which the snake uses to propel itself through the water.

  • Although superbly adapted to life underwater,

  • the sea krait is still an air-breathing reptile

  • and it will surface to breath every few minutes.

  • A hawksbill turtle also takes a breath of air at the surface

  • and then makes its way back to the seabed in search of food.

  • In the Andaman the hawksbill turtle is the most common of these ancient reptiles.

  • Hawksbill turtles have a wide-ranging diet

  • that includes cnidarians such as these hammer coral polyps

  • and this jellyfish.

  • Sadly they can be quite indiscriminate in their eating habits

  • and are easily poisoned by eating plastic bottles

  • and other man-made debris.

  • This turtle appears to mistake my camera lens for food.

  • Whereas the hawksbill has two pairs of plates between its eyes,

  • the green turtle has just a single pair,

  • and a less pronounced beak.

  • At Donald Duck Bay, one or two green turtles

  • often hang around moored boats in search of food.

  • With care, they can be fed by hand.

  • Harlequin shrimps have very interesting eating habits.

  • Working in pairs, the shrimps take on sea stars many times their size.

  • Over a period of days,

  • the shrimps systematically sever and eat the sea star's legs.

  • They must be decisive however,

  • because the sea star will reattach its legs, given a chance.

  • The sea star can also regenerate its legs,

  • so the shrimps leave the central disc that contains its vital organs,

  • so that they have a chance to feed on the same individual again in the future.

  • The shrimp feed exclusively on sea stars

  • and cannot live without them.

  • This is known as "obligate predation".

  • By turning the sea star over, it is less likely to escape

  • and the shrimps have access to it's soft underside.

  • For such a small creature, the shrimps have remarkable strength.

  • The larger peacock mantis shrimp does things in a different way.

  • Two of its claws have evolved into red and white clubs

  • that the shrimp uses to smash or stun prey.

  • These formidable weapons are effectively spring-loaded.

  • When the shrimp deploys them

  • they strike their target at a velocity of some 23 meters per second,

  • and their sound can be heard some distance away underwater.

  • Amongst aquarists they have earned the nickname "thumb splitter",

  • and have even been known to smash the glass of aquariums when,

  • presumably, the shrimp mistook its reflection for a competitor.

  • This shrimp is trying to smash an oyster,

  • but occasionally stops its work to give us a colorful threat display.

  • Partnerships are a very important aspect of the reef ecosystem.

  • Skunk cleaner shrimps are often found in the presence of giant morays.

  • The shrimp scours the host for parasites,

  • so the shrimp keeps itself fed

  • while the moray keeps itself clean and healthy.

  • Such mutualism between marine creatures is a key element of survival.

  • Given the opportunity, the shrimps will even clean a diver's teeth.

  • Here at Koh Bon we see a similar example of symbiosis.

  • Variable-lined fusiliers gather

  • to get a valet from a pair of bluestreak cleaner wrasse.

  • The bold, longitudinal stripes of the cleaner wrasse

  • enable fishes to easily recognize it as their friend.

  • This starry puffer opens its gill wide

  • to afford maximum access to a pair of cleaner wrasse.

  • Cleaner wrasse operate out of recognized "cleaning stations":

  • specific locations where fishes go to be cleaned and not to feed.

  • The batfish at Koh Tachai know they can rely on the attentions of bluestreak cleaner wrasse.

  • The less-common bicolor cleaner wrasse also operate here.

  • Without this cleaning service,

  • the host fish may quickly become diseased.

  • Even the fearsome giant moray has entered into this silent contract.

  • However the cleaner's attentions are not always welcome.

  • This honeycomb moray seems particularly irritated by the presence of a cleaner shrimp.

  • And this blackspotted puffer is so annoyed by these cleaner wrasse

  • that it even starts to inflate,

  • a reflex normally reserved for times of great danger.

  • The false cleanerfish is a blenny

  • which has cunningly evolved to closely resemble the cleaner wrasse,

  • yet actually feeds on the flesh of its hosts.

  • This cuttlefish seems to get a lot more than it bargained for

  • when it receives a nasty nip on the eye.

  • Large fishes such as this zebra shark

  • often find themselves with company in the form of a sharksucker,

  • otherwise known as a "remora".

  • The remora's dorsal fin has evolved into a sucker

  • that it uses to attach itself to its host.

  • As well as hitching a free ride,

  • the sharksucker picks up scraps that it's host leaves when feeding.

  • Large pelagic fishes such as whale sharks

  • can play host to great numbers of sharksuckers.

  • The sharksucker lacks the swim bladder

  • that other fishes use to control their buoyancy,

  • and so it needs its host to survive.

  • Sharksuckers do their part

  • by cleaning small parasites such as isopods from the host's skin.

  • Sharksuckers will attach themselves to just about any moving object

  • significantly larger than themselves.

  • For example porcupinefishes,

  • and parrotfishes.

  • Even divers sometimes find themselves playing host.

  • Another fish that likes the slipstream of a much larger host is the cobia.

  • The sight of a cobia almost always indicates that something much larger is close by.

  • Cobias feed on the feces of their host.

  • Manta rays and whale sharks are particular favorites.

  • Shoals of blotched fantail rays can attract hundreds of cobias.

  • This grey reef shark has a cobia and a sharksucker for company.

  • But this grey reef shark is being tracked by rainbow runners, not cobias.

  • At first sight it might seem they are behaving in the same way,

  • but actually the rainbow runners' motive is different.

  • They rub themselves against the shark's rough skin

  • in order to remove algae and parasites from their own bodies.

  • Whitetip reef sharks sometimes get the same treatment.

  • These rainbow runners are cleaning themselves against a free-swimming hawksbill turtle

  • as it returns from breathing at the surface.

  • Feather duster worms are rooted statically to the reef

  • and feed by filtering plankton from the water with their tentacles

  • and passing it into the central mouth.

  • Colorful christmas tree worms

  • embed themselves into porous stony corals

  • such as this lobe coral.

  • They are highly sensitive to disturbances.

  • At the slightest sign of danger,

  • the worm retracts into the coral and seals the opening.

  • When they feel the coast is clear

  • the worms re-emerge in their full glory.

  • This interesting echinoderm

  • is known as a "large burrowing sea cucumber".

  • It roots itself into the substrate

  • and holds its outer tentacles in the current.

  • When it has captured sufficient plankton

  • the tentacles reach down toward the center,

  • allowing the smaller inner tentacles to scoop the food into the mouth.

  • The Graeffe's sea cucumber is very common

  • at shallow depths in the Andaman.

  • Its mouth contains 25 adhesive black tentacles

  • which it uses to walk over the reef

  • and to pick up food from the substrate.

  • This one even attached itself to my camera lens.

  • The mouth of the amberfish sea cucumber

  • contains 18 tentacles

  • and is underneath the body.

  • After digesting what it can from the material it has ingested from the seabed,

  • the waste products are expelled at the anus.

  • But the anus not only serves this purpose;

  • it is also how the cucumber breathes,

  • by sucking water in and out.

  • The Graeffe's sea cucumber breeds by releasing sperm or eggs,

  • collectively known as "gametes", into the water.

  • It waits until the conditions such as current and water temperature are right,

  • then rises up off the substrate into the current

  • to give it's gametes the best chance of a successful fertilization

  • with those of an unknown mate.

  • This phenomenon of broadcast spawning

  • is not unique to sea cucumbers;

  • it is common among many reef creatures.

  • Here, a pizza anemone releases its gametes at night.

  • Over a breeding period that last some weeks

  • oysters release their gametes into the water.

  • Only a tiny fraction of the eggs become fertilized

  • and an equally small number of the resulting larvae survive to adulthood,

  • so the oysters release literally litres of gametes

  • to ensure the species' survival.

  • One of the most intelligent and fascinating creatures found around the reefs of the Andaman Sea

  • is the pharaoh cuttlefish,

  • seen here snatching prey with its long feeding tentacle.

  • Many a time cuttlefishes are found in courtship in shallow water.

  • Cuttlefishes copulate face to face,

  • using their ten tentacles to embrace.

  • The male cuttlefish passes spermatophores into a pouch beneath the female's mouth.

  • He may first use a jet of water to flush out the spermatophores of any previous mates.

  • The couple are so engrossed in the mating process

  • that they seem oblivious to all around them

  • and they allow divers to approach very closely.

  • After copulation the female seeks a suitable crevice in the rocks or coral,

  • and she passes her eggs over the sperm and into it.

  • If fertilization was successful

  • the eggs will hatch around 19 days later.

  • The failure rate is high however,

  • and sometimes the cuttlefish's aim is not too accurate!

  • The male is extremely protective over his female mates after copulation.

  • He will attempt to warn competitive males away

  • with a striped coloration and by raising his median tentacles.

  • But occasionally a confrontation is inevitable.

  • The bigfin reef squid's mating process is similar to that of the cuttlefish.

  • Here we get a rare glimpse of a male escorting a female

  • as she deposits her eggs.

  • The squid can change color rapidly

  • to communicate and to display emotion.

  • At Western Rocky Island this male day octopus

  • is doing everything it can to appear strong

  • by standing tall and using skin texture and color.

  • The octopus suddenly starts digging.

  • Finally he unearths another octopus from its shelter.

  • It's difficult to be certain whether this is a territorial dispute between the two octopuses,

  • or the aggressive mating behavior of a determined male in pursuit of a female.

  • The presence of divers momentarily deters the aggressor

  • and he dives for cover.

  • But his instincts get the better of him

  • and he takes off in pursuit.

  • A tussle ensues.

  • The victim finally escapes.

  • Damselfishes will aggressively defend their territory,

  • particularly when they are guarding their eggs.

  • This day octopus appears to have strayed onto this domino damsel's patch,

  • and feels the full effect of its displeasure.

  • The octopus tries to protect its head

  • but, short of leaving the area entirely,

  • it seems there is little it can do to escape the persistent pecking of the damsel.

  • As air supplies run low,

  • the divers make their way slowly back to the surface.

  • As the boat makes its way to the evening's mooring,

  • a pod of rough-toothed dolphins cruises in the bow wave.

  • A typical Andaman sunset signals the end of daylight,

  • but by night the reef is still alive.

  • A dive under cover of darkness

  • provides an entirely different experience for a curious diver.

  • A lone bigfin reef squid is on the move.

  • This one is feasting on an Indo-Pacific sergeant.

  • A cuttlefish has also struck lucky,

  • but its spinefoot prey continues to struggle.

  • Moon jellyfish drift by in the current.

  • A great barracuda, one of the key predators on the reef, cruises past.

  • A cup coral's pretty polyps are extended.

  • Amongst a group of lionfish

  • this honeycomb moray pounces on a goldband fusilier

  • and swallows it whole.

  • Many reef fishes however,

  • including the blackspotted puffer,

  • use the night time to sleep.

  • A spotted sharpnose puffer takes rest on the reef.

  • Ember parrotfish are a favorite target of sharks

  • and sleep under ledges where they are difficult to get at.

  • Aside from electro-detection, sharks use smell to detect prey.

  • To guard against this,

  • and attacks from other predators such as large morays,

  • parrotfishes often surround themselves

  • in a scent-proof cocoon of secreted mucus.

  • As a diver it's very difficult to observe fishes by night without disturbing them.

  • Many reef fishes are naturally confused and disorientated by divers' lights.

  • This blue triggerfish shows its agitation by raising its dorsal trigger.

  • Ornate ghost pipefish are amongst the most confused

  • by the apparent early appearance of daylight.

  • Banded coral shrimps however

  • seem to enjoy the presence of divers.

  • The extra light draws in micro-organisms

  • and the shrimps take advantage,

  • plucking food from the water.

  • This large snapper is tended to by a cleaner shrimp while it rests.

  • ...as is this fimbriated moray.

  • Space is at a premium on the reef,

  • and this fimbriated moray finds itself sharing its habitat with a variable coral crab.

  • Crabs hide deep within the reef during the day

  • and are hardly seen,

  • but at night they are highly active.

  • Females carry their eggs under their apron for a few months

  • while the embryos develop.

  • This splendid round crab is ready to release her brood

  • and begins pumping her lower body.

  • Thousands of tiny larvae are released and drift away in the current.

  • This crucifix crab tries to appear as large and intimidating as possible

  • by spreading its claws,

  • then attempts to escape our attentions, not by swimming,

  • but by the more conventional sideways shuffle.

  • Tiny bull crabs crawl around reefs by night

  • ...and often attach themselves to sea fans.

  • Flat rock crabs hide in crevices in the reef.

  • Swimming crabs are here too.

  • They strongly defend their territory against competitors

  • such as this passing common decorator crab.

  • This species grows large claws which can dwarf its small carapace.

  • They decorate themselves with other marine organisms for camouflage and defense.

  • This one protects itself with stinging hydroids.

  • The horrid elbow crab becomes completely encrusted with growth.

  • Many crabs can voluntarily shed a claw during conflict,

  • but they can regenerate the missing limb when they next molt their shell.

  • Spider decorator crabs cover themselves

  • with small pieces of sponge and other organisms,

  • allowing them to perfectly blend in with the reef.

  • The sponges continue to grow while on the crab,

  • thereby gradually increasing the camouflage.

  • The sponge crab attempts to hide by carrying a large sponge around with its rearmost legs.

  • When discovered, it can take drastic action to escape!

  • Hermit crabs adopt a completely different strategy to self-protection.

  • The crabs themselves don't have a hard carapace like other crustaceans.

  • Instead the crab uses an empty snail shell to protect its soft abdomen.

  • The fourth and fifth pairs of legs

  • are reduced in size and remain inside the shell,

  • while long eye stalks enable the crab peer to out.

  • Hermit crabs literally carry their homes around the reef on their backs.

  • As the crabs grow they look for larger shells to move to

  • and the crab is not always so expert at judging the size of its home!

  • This appears to be a territorial dispute between two anemone hermit crabs.

  • This species carries live sea anemones on it's shell.

  • The stinging tentacles of the anemones provide additional protection for the crab.

  • The anemones benefit too;

  • mobility gives them a wide variety of feeding opportunities.

  • When the crab upgrades to a larger shell,

  • it takes the anemones with it.

  • By day the naked basket star rests

  • although its wriggling arms are a mass of activity.

  • By night the arms extend to filter plankton from the water.

  • Like other stars, the basket star is able to move around the reef.

  • Time limits are up,

  • lantern batteries are fading,

  • and it's time to call an end to diving.

  • From the widest manta ray to the slimmest pipefish,

  • the brightest clownfish to the stealthiest stonefish,

  • the Andaman Sea has truly shown us

  • the sheer diversity of living wonders

  • that inhabit its reefs.

In the north-east of the Indian Ocean,

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