The Napoleon Wrasse with it’s human characteristics is the largest of the Labridae family. It has distinctive thick fleshy lips, like Angelia Jolie, and a large hump on the head above the eyes that becomes more prominent with age.  The males are bright electric blue to green, purplish blue or a dull blue green, whereas the females and juveniles are red-orange above and red-orange to white below.  Mature males are recognized by black stripes along the body and blue scribbles on the head and juveniles have two black lines behind the eyes. The Napoleon is one of the largest fish on the reef with males growing to 2m in length and females 1m. It not uncommon for them to weigh up to 190kg.

Napoleon Wrasse, also commonly known as humphead and maori wrasse reach sexually maturity between 5 and 7 years. The female life span averages 30 years and males 25 years. They are Protogynous hermaphrodites. This is when females become males at about the age of 9. The factors controlling the sex change is unknown. Napoleon Wrasse are solitary but at certain times of the year when spawning is due to take place, the adults will move down current towards the end of the reef. The fertilized eggs float in the plankton until the larvae hatch and then they settle onto the substrate.

The Napoleon adults are found on steep coral reef slopes, channel slopes and also lagoon reefs varying in depth from 1m to 100m deep. The Juveniles are often found amongst branching corals in the shallows. They are diurnal feeders being active during the day and sleeping in favoured caves and large crevasses.

The Napoleon is carnivorous and is an important part of the food chain in maintaining a healthy and balanced reef. They are opportunistic predators eating crustaceans and mollusks. They are one of the few predators of the toxic sea hare and box fish. They have also been known to eat the almost indestructible crown of thorns.

Unfortunately, one of the main predators of the Napoleon is man!!! They are highly prized particularly in South East Asia and are one of the most highly valued fish in the luxury live reef fish trade. They will fetch $100 per kilo and $400 for a set of lips!!!! The Napoleon has been classified as a threatened reef fish. Their slow reproductive cycle, late maturity, longevity, predictable spawning sites and natural rarity have made it highly vulnerable to over-exploitation.  In numerous countries it has become a protected reef fish making commercial fishing for it illegal. It is necessary to control fishing practices as there has been a decline in numbers and unfortunately it is not possible to breed this fish in captivity.  In 1995 the Maldives banned the export of this fish and the population has increased.

Napoleon Wrasse are naturally curious and will often spend time around divers. Some have even been known to recognize individual divers and actively seek them out.

If you would like to know more about the identification of species why not sign up for on a  Underwater Naturalist Specialty Course, which will enhance your knowledge and highlight the key things to look for or a cruise on board MV Scuba Adventure or MV Scuba Fun for a chance to see these for yourself.

Octopuses are the master of disguise on a reef. Many times someone may be pointing at apparently nothing and then as with a 3D photo and octopus appears!!!! This remarkable creature is compelling watching as it changes colour and texture. Camouflage is possible due to specialized skin cells that can change colour, opacity and reflectiveness of the epidermis. It is believed that the colour changing is a means of communicating with others and also to warn of danger. The muscles in the skin enables the octopus to alter the texture of it’s mantle so as to blend in with it’s surroundings, for example, the bumpy texture of a rock. There is also evidence to suggest that octopus living on a complex habitat such as a reef and are more active during the day have a more developed skin than the sand dwelling and nocturnal partners.

There are 300 recognised species of octopus worldwide. All are known to be venonmous, but only the blue ringed octopus is deadly to humans. Octopuses have 4 pairs of arms and 2 eyes and are bilaterally symmetric. There is no internal or external skeleton, which enables the creature to squeeze through small spaces if fleeing from predators. They are regarded as the most flexible and intelligent of all invertebrates having both having long and short term memory.  There is only one hard part of the body, this being the beak, or mouth that is found at the centre point of the arms.

Octopuses have very good eye sight and some species are able to distinguish colour. They are also able to distinguish the orientation of their body to the horizontal using two organs that are attached to the brain called statocysts. There is also an automatic reponse that keeps the eyes orientated, so that the pupil slit is always horizontal.

The sense of touch is excellent and the suction cups found on the arms have numerous chemoreceptors that enable the octopus to taste what it touches. The arms also show a variety of complex reflex actions. This is due to 2/3 of the neurons of the complex nervous system being located there. The arms also have tension receptors, so the octopus can determine if the arms are stretched out, but the receptors are not sufficient for the brain to determine the actual position of them.

This creature also has three hearts, two are branchial hearts that pump blood to each of the two gills and the third pumps blood through the body.  The blood contains a copper rich protein called hemocyanin, which is effective for transporting oxygen in cold conditions and environments where there is low oxygen pressure. The protein is dissolved in the plasma and gives the blood a bluish colour.

The life expectancy of the octopus is short from 6 months to 5 years. The death of the octopus is genetically programmed and results after reproduction. The male of the species may live for a few months after mating, but the female will die shortly after the eggs are hatched.  During reproduction the male will insert a specialised arm called a hectcotylus into the female’s mantle where it deposits spematophore (packets of sperm). Some species can keep the sperm alive inside the female for a few weeks until the eggs are mature. Once fertilization occurs the female will lay her eggs, which she hangs in strings from her lair or individually on the substrate. This varies depending on the species.  A female may lay upto 200,000 eggs. The incubation period is approximately a month. During this time she is the protector and will gently blows a current of water across the eggs providing them with enough oxygen. However, it is to her detriment as she will not hunt. It has been known for the female to ingest one or more of her arms for sustenance.  Once the eggs are hatched she will leave being very weak and defenseless thus dying.  The larval octopus will drift for a while in clouds of plankton where they feed. . Plankton eaters such as mantas and whale sharks are obviously a threat to the larvae. When they are ready they will descend to the ocean floor.

Octopuses move by crawling on their arms or by swimming. They swim in a horizontal position with the arms behind. Movement is by expelling a jet of water from a contractile mantle. This is one of the primary defense mechanisms as they are capable of fleeing at great speed. Another form of defense is the use of thick blackish ink, melanin, which is dispersed in a cloud. It is believed that the ink reduces the olfactory organs of some hunters that hunt by smell, for example, sharks. It is also known that an octopus is capable of detaching an arm as a distraction when under attack.  The mimic octopus is highly flexible and is able to change shape to look like other creatures. It has the capability of changing to look like a more dangerous creature than the one that is attacking.

These remarkable sea creatures are worthy of watching while on a dive. If you are lucky enough to see one then do not get too close as the octopus will hide in crevices and cracks in the substrate. It is better to observe from a distance away and slightly elevated. Be patient and wait motionless. The octopus will eventually gain confidence and gradually come out into the open for you to enjoy the moment!!!!

If you would like to know more about the identification of species why not sign up for on a  Underwater Naturalist Specialty Course, which will enhance your knowledge and highlight the key things to look for, or a cruise on board MV Scuba Adventure or MV Scuba Fun for a chance to see these for yourself.

Harlequin Shrimps are a very flamboyant looking and a delight to see. There are two species of harlequin shrimps, namely the Hymenocera Picta found in Hawaii and Hymenocera Elegans found in Andaman Sea. They are commonly known as clown shrimp, painted shrimp and dancing shrimps.

The Harlequin shrimp is unlike other species in that it is a slow mover and not very agile. The beautiful bodies have stunning coloration with the body being a pinkish white or white with large purple edged pink spots. There may also be red and orange tones depending on the local environment.  The shrimps vary in size averaging between 2cm-4cm. The females are larger than the males and can be identified by the coloured abdominal plates. The male’s abdominal plates are white. It is believed that the vivid appearance of the shrimp is enough to deter predators. It also indicates that it may be toxic to eat as brightly coloured creatures often are. This is not the case with the shrimp. The two large flat pincers constantly move even when the shrimp is stationery, hence the common name “dancing harlequin shrimps”. The eyes are positioned on the end of stalks and the antennae are flattened, looking very leaf like.

Harlequin Shrimps are very shy and are found in mating pairs. They are monogamous and are very territorial usually covering an area of up to 10m square.  They are predominately nocturnal and will feed during twilight or under the cloak of darkness. During the day they are found in hiding places on a rocky or coral substrate.  This species of shrimp are rare and do suffer as a result of coral damage. The Indo-Pacific species is more common that the Hawaiian species, because over the years the latter has been actively collected for the aquarium trade.

Moulting occurs once a month. During this process the shrimp will hide until the new shell hardens. It is usual for simultaneous molting to occur. The molting also gives the opportunity for the shrimp to replace missing limbs, this may take more than one regeneration.  The mating couple will reproduce after the female as completed her molting process. She will lay between 100 and 5000 eggs per season and tends to them until they are hatched.

The Harlequin Shrimps are predatory carnivores. They are ruthless and extremely strong. The shrimps work as a team and detect their prey by scent. They live on a diet of starfish. Once the starfish has been located the pair will prize the arms from the rock and overturn it, thus rendering the starfish helpless.  The starfish may be 10 to 20 times larger than the shrimps. It has been known for the shrimps to drag the starfish to the lair where it acts as a living larder. It is kept alive by the shrimps feeding it.  The shrimps dine on the tube feet starting at the tips and working inwards to the centre plate, thus keeping their food source alive for as long as possible. Occasionally, a starfish may detach an arm or two to make an escape!!!! It is fortunate that starfish have the capability to rejuvenate their limbs…..

If you would like to know more about the identification of species why not sign up for on a  Underwater Naturalist Specialty Course, which will enhance your knowledge and highlight the key things to look for or a cruise on board MV Scuba Adventure or MV Scuba Fun for a chance to see these for yourself.

The Seahorse is one of the “must see” critters amongst divers in Phuket.

They are found in tropical and temperate waters worldwide often in sheltered areas, for example, sea grass beds, coral reefs and mangroves.  Seahorses belong to the fish genus Hippocampus, a name derived from ancient Greek, Hippos meaning horse and Kampos meaning sea monster. The Seahorse has been named for its’ equine profile. Although the seahorse is classified as a bony fish it does not have scales, but has a thin layer of skin that is stretched over a series of bony plates.  There are fifty species of Seahorses worldwide ranging in size from 1.5cm to 35cm each having its’ own distinct number of plates.

Seahorses are poor swimmers and are found often resting with their prehensile tail wound round a stationary object. They are territorial with the male staying in a 1m square of their habitat, whereas the female may travel up to 100times that area. All species of Seahorses swim in an upright position with the dorsal fin moving rapidly up to 35 times a second!!!  The pectoral fin is positioned behind the eyes and this is used to steer. There is no caudal fin. Each individual has a coronet on the head that is unique to the individual. They also have eyes that move independently.

It is believed that Seahorses mate for life, but there is no data to prove monogamy. However, it is known that a breeding pair will be together for the breeding season.  The courtship between the male and female cements the bond between them and is a very important part of the relationship and may take several days. The courtship behavior synchronizes the movements, so when the female is ready she can deposit her eggs into the male brood pouch. One of the unique things about Seahorses is that the male incubates the eggs. The Courtship dance is also known as the “pre-dawn dance” They may change colour, swim side-by-side holding tails and spiral in unison. Once the pair have bonded and the female is ready to transfer her eggs a courtship dance lasting up to 8 hours will take place. During this time the male will pump water into his brood pouch, which is on the ventral or front facing side, expanding it.  As the pair drift upwards the female inserts her ovipositor into the male’s pouch depositing her eggs.  Once the eggs are transferred the pair sink and the female swims away.  The amount of eggs laid depends on the species ranging from 5 to 1500, but the average is 100 to 200.

Once the male has the eggs they are fertilized and are surrounded by a spongy tissue. The pouch acts an incubator and provides oxygen and a controlled environment where the salinity is regulated to prepare the young for life in the sea. By the end of the incubation period the male consumes a third more oxygen than before mating. The female energy expenditure while generating the eggs is twice that of the male during incubation. The gestation period is 2 to 4 weeks during which time the female will visit the male on a daily basis interacting for about 6 minutes.  When the fry are formed the male contracts the pouch releasing the young into the water column. The birth normally happens at night allowing the male to receive more eggs from his partner the following morning. Once the young are ejected into the water they are independent as there is no parental care.

It is estimated that less than 0.5% of the fry survive to adulthood. The survival rate is higher compared to other fish due to the protected gestation of the male. It is believed that the male takes the role of incubator because the female takes a long time to produce eggs. This reduces the time between clutches, thus increasing the amount of young.  When the eggs are ready they must be transferred to the male’s pouch within a few hours. If this is not possible the eggs are ejected into the water. Once the eggs are laid the female reduces in size. The eggs are equivalent to one third of her body weight!!!

The Seahorse has an unbelievable appetite and eats constantly. It is possible for an individual to eat 3000+ brine shrimp in a day. They will also consume minute fish, crustaceans and plankton.

Unfortunately, there is very little data on Seahorses, so it is impossible to assess the population and whether or not it is endangered. The use of Seahorses in traditional Asian medicine has put pressure on the population as this type of medicine will only use fish from the natural habitat and will not consider individuals from captive breeding. This combined with the deteriorating habitats and souvenir collecting does point to the extinction of some species.

"Take that purrfect shot"

The Seahorse is a prized treasure amongst underwater photographers, as getting the perfect shot can be a challenge due to the coyness of the creature. If you would like to capture “the shot” why not consider doing a Digital Underwater Photography Specialty Course, and now be able to spend more time learning to take the photographs why not take the theory for the Speciality with E learning?

It is almost guaranteed that when you dive on coral reef from Phuket, Thailand  you will encounter the vibrant coloured Parrotfish.

"Hello"

Parrotfish are abundant and range in size from 30cm to 1.4m. How did this family of fish (Scaridae) derive the name Parrot?  Just have a look at the dentition; numerous teeth are fused to form a beak, much like a parrot’s beak. The teeth aid feeding activity as the Parrotfish eats algae from coral and rocky substrates, often leaving teeth scars behind. Parrot fish are considered to be herbivores, but they are not necessarily vegetarians as the large Green hump head parrot fish is known to include coral polyps in it’s diet.  The feeding activity of the parrotfish is important in the production and distribution of coral sands. If you watch Parrot fish excrete you will notice that it is fine white sand. This has been responsible for helping create small islands and beaches worldwide. It is estimated that a Parrotfish is capable of producing 90kg of sand per year!!! How is this possible? The beak takes the coral or rock and then it is pulverised by a set of grinding teeth located in front of the oesophagus. The digestion procedure gives sand as the end product. The Parrotfish eating habits are paramount in controlling algae growth resulting in a thriving reef. Another little fact about the Parrotfish is that their teeth continuously grow and by chomping on rock keeps the growth in check!!

"Parrotfish"

Parrotfish are known to reproduce throughout the year, but more predominantly during the summer months. This family are generally sequential hermaphrodites starting their life as female then change to male. However, one exception to this is the Marbled Parrot fish, which is known not to change sex.  Parrotfish are pelagic spawner’s. This means that the eggs are spawned in mid water and are buoyant, the eggs float freely eventually resting on the coral where they stay until they hatch. The Parrotfish larvae appear not to have any characteristic facial features or colouration for the first few days after hatching.

Juveniles have a different colour pattern to the adults and it is possible for juveniles of some tropical species are capable of changing colour temporarily to mimic other species. It is not unusual to see “flocks” of juveniles swimming en mass over a coral reef. Often they are dark in colour and occasionally an individual can be seen changing it’s pigmentation.

The Parrotfish are unique in that they are able to secrete a mucus cocoon from a gland near the mouth. This provides protection from nocturnal predators. Also, it can act as an early warning system allowing the fish to flee if the protective cocoon is disturbed. The Parrotfish is only able to produce this cocoon once during the night, so it is important when night diving not to disturb the sleeping Parrot fish.

The Parrotfish skin is covered in a mucus substance that is believed to have antioxidant properties that can help repair any damage that may occur to the skin. Also, the mucus has anti parasitic properties, repelling potential parasites.

There are approximately 80 identified species of Parrot fish, which are abundant in and around coral reefs worldwide. They are a close relative to the Wrasse family, but there are some distinctive features that help with identification. When trying to identify a parrotfish look for an elongated, blunt head. The body of the fish is deep and brightly coloured with defined large scales and finally look for the unique bird like beak.

"Hump Head Parrotfish"

If you would like to know more about the identification of species why not sign up for on a Aware – Fish Identification Specialty Course, which will enhance your knowledge and highlight the key things to look for.