Kath joined the boat mid afternoon to meet  Tim and Donna, repeat customers since 1999, and Amit who had just completed the South trip. The remaining nine customers were brought to Scuba Adventure by John Stanley who was the Dive Master for the trip. It was great to have an international group with people from Germany, Switzerland, India, America, UK, Australia and China.

With the briefings completed, cabins allocated and equipment prepared it was time to chill out and enjoy the overnight cruise to the Similans.

The first morning brought a surprise! Jack, our engineer called Kath to the dive deck where we had an unexpected guest, a banded sea snake!! Customers grabbed their cameras and then it was gently persuaded to leave the boat.

Banded Sea Snake – Louise Murray

The first dive of the morning, the check dive, was on Anita’s Reef. Lovely easy dive going with the current toward the boulders. With everyone comfortable we then headed to Koh Bon. John and his group of Advanced Open Water students were dropped in the bay together with Tim and Donna while the others were dropped on the ridge. The wall area approaching the ridge was covered in glass fish, so much so that it was difficult to see the reef. Two Giant Moray Eels were out in the open fighting. As they tried to bite each other their bodies became intertwined.

Moray Eel – Phil Lineker

This dual lasted for several minutes before on retreated in defeat. Unfortunately, we didn’t see any mantas, but around the reef had so much activity. John’s group was lucky enough to see two Napolean Wrasses. Third dive and Koh Tachai Pinnacle. Thankfully there was very little current. The Pinnacle was prolific with marine life as always. One thing that was unusual was a tight group of Silver Jack spiralling towards the surface. It was a tornedo of fish!!!! The advanced students were to get an extra navigation dive on the reef as part of their course. The forth dive was to be a night dive on Koh Tachai Reef. Some were apprehensive as they had never been on a night dive before, but this was short lived once they started diving. The highlight of the night dive was an octopus that we were able to watch for a while. These are incredible creatures that have the capability to change not only colour but texture.

Octopus – Cedric Saveuse

Day 2 and an early start with the engines firing up at 4.30am. Our destination Richelieu Rock. The visibility here was awesome. During the two dives we saw a host of things including a Seahorse, various shrimps, tomato clownfish, bent stick pipefish, cleaner pipefish, cuttlefish, the list is endless. Our eyes were constantly scanning as the previous day there had been 3 whale sharks spotted on the Rock, but unfortunately we were not blessed. As we wanted to maximise the chance of seeing Manta Rays and Whale Sharks we headed back to Koh Tachai where we had two action packed dives with hunting predators, Napoleon Wrass’, Red Tooth Trigger fish dancing like confetti.

Manta

Day 3 brought an early start on Koh Bon. The ridge still covered in glassfish was action packed as they were being hunted relentlessly by the larger fish on the reef. It is an impressive to sight to see the bait ball swirling in all directions to avoid being caught. Towards the end of the dive on the ridge the first Manta Ray made its appearance. It slowly past the ridge and headed out into deeper water. Kath saw it as she was on her safety stop so a decision to stay for one more dive was made as not everyone had had the opportunity to see it. We were dropped on the north part of the reef and we headed towards the ridge. As you can imagine the second dive was filled with excitement with the possibility of seeing this majestic creature. We unfortunately didn’t see it, but we still had a great dive. As we came on the boat the crew were quick to tell us that they had seen the manta from the boat shortly after we had jumped. At this time there were more boats on the dive site, so a group decision was made to move to the Similans.

Sea Horse – Cedric Saveuse

Dive 3 was on Three Trees on Island 9. Kath drew her map with the marine life they were likely to see on the reef and then the customers played the guessing game trying to identify them. (Maybe she should take some drawing lessons!!!) We crossed the sand to the outer boulders, which is a very scenic part. Here Paul spotted 3 Seahorses sat in a fan. A lovely bonus!! There was a nice gentle drift on the sloping reef, so with no effort we watched the countless fish as we passed by. Our final dive of the day was West of Eden on Island 7. This site has some very beautiful hard and soft corals and it is like diving in an aquarium. However, there were two major highlights to this dive. In the shallow area we could not believe our eyes when we saw what could only be described as a swarm of parrot and surgeon fish. There were hundreds all tightly packed. We hovered and watched them for quite a while and then they peeled off in a line and swam further along the reef.

Kath and the Turtle

Then came the ultimate turtle experience. On seeing the divers he stopped eating and came to investigate. This curious turtle was so relentless in it’s approach to the divers, especially Susan, that it had to be gently pushed away several times. Customers managed to get some great photos.

Susan and the Turtle

Day 4 and a decision had been made the previous night by the customers that the early morning dive should be on West of Eden again as there was so much to see. So, at 6.45 we went for our dive. The reef was just waking up and we were witness to some great hunting action around the stunning coral blocks. There was a current, so instead of turning around at the corner we continued around the Island where there were some schools of Rainbow Runners in the deep together with some large Tuna cruising by. Our final dive of the trip was Shark Fin Reef. This is the furthest south we can dive in the Similan Islands. This reef is known for the stunning topography of the huge granite boulders that stretch for about a kilometre. It is constantly adorned by neon blue fusiliers that run like a train along the reef. Our main highlight of this dive was seeing a shark…not just a shark….one that Kath had never seen in the Similans Islands. It swam straight through the group. Amit had video footage of it, so we were able to identify the shark as a Silver Tip.

The Similans

This trip was a very social trip with customers even conducting dive briefings. Although, only a few of us saw the Manta everyone was more than happy with the diving. We had such diverse marine life and behaviour that this trip will be remembered by all. Michael, Cindie and Ron decided to book for the next trip south to Hin Daeng and Hin Muang. Under the guidance and Instruction of John, Cindie, Ron and Xin completed their Advanced Open Water. Xin also completed her Digital Underwater Photography and Peak Performance Buoyancy Specialities. Congratulations to them all!

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.