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 Similan Marine Park is located 70km west of Thailand Phang-Nga province. This group of islands is considered to be one of the top dive destinations in the world, mainly due to the clear water that surrounds the islands.

Similan was derived from the Malay work for nine “Sembilan” as the little archipelago is made up of nine islands. The islands do have local individual names, but are usually referred to by their respective numbers from North to South.

The Similan’s were designated as a National Park of Thailand in 1982 and cover an area of 128km2, which includes Koh Bon and the two rocky outcrops of Shark Fin Reef and Hin Pusa.

In 1998 an extra 12km2 of area was added when Koh Tachai was added to the park, which is now a total area of 140km2, of which only 15km2 is land.

Most of the islands are uninhabited with the exception of Islands 4, 8 and koh Tachai, which have national park offices located on them.

With the nine islands you get a wide variety of experiences, activities and stunning views, there are white sand beaches and massive boulder formations.

Underwater there are amazing coral gardens and diverse marine life ideal for all divers.

The topography differs between the eastern and western sides of the islands. The east side consists of sandy bottoms with wide and colourful soft and hard coral fields that slope down to 40m in some areas. They have gentle current and make for easy diving.

The west side is characterized by large, stacked granite boulder formations which create tunnels and archways with impressive scenery. Currents here can be unpredictable which can make the diving more challenging for beginner divers. But this side is exposed to the open sea and provides good opportunities to spot big pelagic life.

Island 1               Koh Hu-Yong

The second largest island lies 8km south of island 4, it has the largest white sand beach of the Similan National Park which is located on the north side of the island. The beach is a protected area and has a Turtle hatchery, you need special permission from the forestry department to enter this island.

Island 2 and 3     Koh Pa-Yang and Koh Pa-Yan

These two islands are also protected, their topography is granite boulders with mountains and cliffs, no beaches. At resent all the first 3 islands are closed to diving in an effort to preserve the underwater environment. The most southern dive sites are the rocky outcrop of Shark Fin Reef and the submerged site of Boulder City.

Island 4               Koh Miang

The island has a marine park office, camping, small bungalows and a fresh water supply. There are 2 beaches, Haad-Yai or Princess beach on the north and Haad-Lek or Honeymoon beach to the East. There is a trail that runs between the two through the forest. Also on the island is a view point where once you reach the top has a spectacular view of the south islands of the Similans, the trek to get there is a little energetic though.

Islands 4 and 5   Koh Ha and Koh Hok

These two islands are located to the East of Island 4 and are the smallest in the group. The landscape underwater is spectacular with both fringing reef and boulder formations.

Island 7               Koh Pa-Yu

The island has a combination of granite formations and sand beaches. The East side of the island is now closed to diving, but the north and west sides offer rocky pinnacles as dive sites which are covered in soft corals. Again these sites are open to the ocean so currents can be encountered along with the bigger pelagic life.

Hin Pusa

Is located between islands 7 and 8 and is a group of boulders known as “Elephant Head Rock” as the shape resembles the head of an elephant. The site is recommended for experienced divers due to the depth and current.

Island 8               Koh Similan

Is the highest and largest of the islands and has a marine park office and camping in the North of the island at Donald Duck Bay. It is also where the famous Sail Rock is located which is a symbol of Similan. The view from the Rock shows the North part of the Similans. There is no diving on the west or East side of the island, leaving only the North area available.

Island 9               Koh Ba-Ngu

The island has no beach, but is a favorite with divers due to the scenery underwater, it has a mix of coral reef and rocky outcrops.

Koh Bon

The island is North east of Similans, with no sand beaches it is a limestone island with an unusual “hole” which traverses the island on the west side caused by sea erosion. The most popular dive is the ridge where a cleaning station for Manta Rays can be found.

Koh Tachai

This is most Northern part of the Similan Marine Park.  The island has a beautiful white powder beach where the park office is located. With many dive sites including a plateau to the south it is a popular dive destination.

Richelieu Rock

Although not part of the Similan marine park this is often dived on the same liveaboard trips. It is actually part of the Surin Marine Park and is located between the mainland and Surin islands. It is a submerged pinnacle know for it colourful soft coral and rich diversity of life, which can include the smallest creatures such as ghost pipe fish and sea horses to the largest of whale sharks and Manta rays.

A Surface Marker Buoy, also known as an SMB or safety sausage is an essential piece of kit for the safety conscious diver.

There are several types of surface marker buoys on the market including the open ended and self-sealing.  Scuba Cat has for several years, stocked a range from the Company “Surface Marker”. Udo Hartig, a diver himself, for optimum visibility, durability and ease of use, has designed this particular range.  It is a range that has proved popular amongst professionals and recreational divers.

"Surface marker"

An SMB is highly recommended in areas where there is boat traffic. The deployment signals to the boat Captain that there are divers completing a safety stop (5metres for 3 minutes) and are about to surface.  Deployment will also aid divers as it can be used as a reference to maintain the correct depth whilst on the safety stop.  An SMB is also essential when drift diving as it enables the boat crew to track the divers in a current.  Should the diver surface away from the boat the use of an SMB will minimize the wait on the surface, particularly in poor conditions such as high waves and poor light conditions. After all, it is so much easier to see a brightly coloured SMB at distance as opposed to a small head in a large ocean!!

Surface Marker have produced two open ended SMB’s that are compact and come complete with a carry pouch that can easily be attached to the BCD. The SMB’s are made from very durable 210D Nylon and are dual coloured, orange one side and neon yellow on the other. This is the best colour combination for a recreational diver. The orange is bright in strong sunlight and significant glare, whereas the neon yellow is excellent for diminishing light conditions. They also have “Diver Below” written in bold letters. The open-ended SMB’s come in two sizes 145cm and 175cm. The latter is a deluxe model and also has a reflective strip, which increases the visibility of the diver.

"Surface Marker"

The one component that sets these buoys apart from other products on the market is the innovative Webbing Deployment System in also known as WDS. This system is simple to use and minimizes risk of entanglement, which is common when SMB’s are used with string. The webbing system folds neatly and is secured with a small bungee cord. As the SMB goes to the surface the webbing unravels easily and it can be effortlessly gathered on ascent.  This particular system eliminates the use of a reel, which can be daunting for some divers. It is definitely a simplistic system that is proven to work. The ideal depth to release the SMB is at 5.5m, which is ideal for the safety stop. The diver can easily maintain contact with the webbing by using the stainless steel thumb ring. This can easily be released should the need arise.

The Surface Marker Pro is a self-sealing SMB, which is commonly used by professionals and technical divers. These buoys are designed to be inflated at depth. The self-sealing internal baffle ensures that the SMB remains fully inflated on the surface. Self-sealing SMBs are fitted with an over pressure release valve, which allows expanding air to escape as it ascends. This particular SMB comes in three colour combinations that cover all requirements. Technical divers on ascent and decompression stops normally use the orange. This colour signifies that all is well. However, should a problem arise then a technical diver will deploy neon yellow which indicates to the surface support that a problem has arisen and that maybe immediate assistance is required. It is also possible to attach a diver’s slate to the SMB, so communication with the surface is possible.   Instructors tend to favour the dual coloured SMB, which offers optimum visibility in all surface conditions. The range of self sealing SMBs are also furnished with the highly visible SOLAS tape and an attachment for strobes or a cyalume stick.

It is possible to encounter problems when deploying an SMB.  One problem that may arise is a jamming reel when using a self-sealing SMB, which does not have the WDS system.  It helps to have a simple reel or use a finger reel that will not jam.  Surface Marker has finger reels available that will fit snugly into the carry pouch of the SMB, which reduces the bulk of equipment.  The finger reels come complete with 30m of line, a stainless steel double ended snap hook and a thermoplastic spool for durability. When using any reel system be mindful of the possibility of entanglement and do not attach the reel to diver. If the SMB is dragged for any reason and you are attached then a rapid ascent may result.

"Finger Spool"

When inflating the SMB it is recommended to keep your regulator in your mouth at all times. If you use the primary air source and problems enfold then it is difficult to resolve them. It is important to remain calm and in control. When inflating the SMB it is advisable to use one of two methods. Firstly, the alternative air source can be held under the open end of the buoy and air can be purged inside. However, be mindful that in cold conditions this may result in a free flow. The second method of inflation is open the buoy above the primary demand valve and exhale allowing the air to enter the SMB.

"Thank you"

Surface Marker also supply 25kg and 65kg lift bags. Scuba Cat has been loaned several by Surface Marker for use on the clean-up events that are held at least bi-annually. The main events are Earth Day and International Clean-Up. The latter event is a extended to a weekend accommodating participants on one of the two liveaboards, MV Scuba Cat and MV Scuba Adventure.  The loan of the lift bags has proved invaluable over the years for lifting various objects varying in size. They are also ideal for marking objects that need lifting on subsequent dives. The lift bags are available in orange and neon yellow and are made from the very durable 210D Nylon, the same material as the SMB’s. The bags are furnished with a top handle and dump valve, which allows the diver to make a controlled ascent rate when surfacing. They also have a strong stainless steel ring for attaching rope. The self-sealing system ensures that the lift bag will remain inflated on the surface.

One of the latest products is the signal mirror. This is compact and can easily be slipped into a BCD pocket. Should you find yourself in the daunting position of not being seen by a boat the mirror comes into it’s own. The unique feature of the mirror is that it can be directed at a specific target and can be visible for 32km!!!!! You could even signal to a passing aircraft…

"Signal Mirror"

Signalling devices are a must. If you would like to become more confident deploying an SMB then why not do the Distinctive SMB Deployment Speciality or The Drift Diver Speciality.

Search and Recovery is the ideal Speciality if you would like to learn how to use lift bags.