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.

Scuba Cat Diving has been offering the Nitrox Enriched Air Specialty since ‘s introduction of the course in 1996. Once considered to be dangerous, it now is widely accepted and very accessible. Diving with Nitrox Enriched Air allows us to safely extend our bottom times and after all, time underwater is what it’s all about!

Since its introduction in recreational diving 1985, Nitrox Enriched air has slowly changed from being controversial to widely accepted. It is now our most popular Specialty Program and all our Daytrip boats are equipped with Oxygen Clean Compressors, which enables us to make Enriched Air available to all Nitrox certified customers.

Diving with Nitrox Enriched Air is most beneficial on dives between 18 and 30 meters. The reduced Nitrogen in the breathing gas means less Nitrogen loading and thus longer dive times.

What is Nitrox?

The air we breathe every day typically consists out of 78% Nitrogen, 21% Oxygen and 1% other gasses. In simple terms, Nitrox Enriched Air in Scuba Diving is any breathing max with an oxygen percentage exceeding 21%. The most popular mixes are EANx 32 (with 32% oxygen) and EANx 36. For recreational diving, breathing gases enriched to 40% oxygen are acceptable and up to 60% with Semi Closed Rebreathers.

Most scuba equipment, including regulators, BCD’s and dive computers are compatible with Nitrox Enriched Air up to 40% when they come from the factory, however you should check the manufacturer’s guidelines.

The normal air we use in scuba diving mainly consists out of Nitrogen (approx. 79%) and Oxygen (approx 21%)*.  Dive tables and computers are based on calculation of theoretical Nitrogen loading. This loading is expressed in Foot Sea Water (fsw), which is directly related to the Partial Pressure of Nitrogen. So, as most divers already know, the nitrogen loading is based on the depth of the dive and the amount of time we spend underwater. Besides these two elements, the third factor that determines our nitrogen loading is the percentage of Nitrogen in the gas we breathe.

In Scuba Diving, Enriched Air Nitrox is any gas mix with more than 21% oxygen. Our body doesn’t use the extra oxygen in the mix, but we do benefit from the reduced Nitrogen. The reduced nitrogen will reduce the partial pressure of nitrogen when we dive and reduce the nitrogen loading, thus extending our bottom time.

Nitrox Enriched air was first introduced as a recreational breathing gas in 1985, which caused major controversy among Scuba Diving experts. It took another 11 years before it became widely accepted with ‘s support of Nitrox Enriched Air as a recreational breathing gas and its introduction of Educational Material and the Nitrox Enriched Air Speciality course in 1996.

Most dive centres have Nitrox Enriched Air available and some boats have Nitrox available onboard.

Scuba Cat’s MV Scuba Adventure, includes several free Nitrox fills on every trip to allow longer dive times. MV Scuba Fun and MV Scuba Cat both have the facility for Nitrox on board meaning that you can take your Enriched Air Diver Specialty during your diving with us no matter which boat you are on. The course is available as a Elearning course, so you can complete the theory from your own home and enjoy the diving on your vacation.

Similan National Park

The Similan Islands National Park is world famous for white sandy beaches, clear blue waters, beautiful sunsets and amazing huge boulder formations. Here you will find some of the most amazing natural scenery Thailand had to offer.

"Donald Duck Bay"

They are easily the best dive sites Thailand has to offer and very rank high in must visit list of Dive Sites in the world.

MV Scuba Cat Live aboard cruises around these Islands for 6 months of the year allowing divers of any level and snorkelers to take in this amazing beauty in one of the most relaxed atmospheres of all liveaboards in the Similans. She has a unique liveaboard schedule allowing a stay from 2 days 1 night, with a maximum of 20 customers staying on board. We are proud to have so many customers who come back to us year after year – I am sure you will agree after a trip on board.

"The Cat"

Rob Fraser-Thomson is one of our many repeat customers’ with Scuba Cat Diving.

“I started diving in Thailand in 1999 whilst doing my IDC with a company based in Kata. It wasn’t for another 2 years that I returned to Phuket after working in Italy. I had heard good things about a company called “Scuba Cat Diving”, during the IDC from other students and other divers, so decided to book my trip with them.

The MV Scuba Cat is based in Simians during the high season, a spectacular group of islands north west of Phuket. Unlike other liveaboards, the boat is permanently based in the islands, customers are carried to the liveaboard via minibus and speedboat, the Similans are a long way from the mainland so this saves much time. You can be diving within 30 minutes of arriving on the boat, after the boat and dive briefing off course.

I have heard people mention that the transfer takes a long time but most the other dive companies take longer to sail from the mainland, the Similans are far out to sea and a world-class dive site.

During the low season the MV SCUBA CAT is based at Racha Yai, a group off islands south of Phuket, it is usually quieter at this time of the year but the diving is just as good. If you have a good eye, this area is rich in the smaller species you don’t spot in the Similans.

"The View during low season"

Captain Min and his crew are always a bonus being very helpful to new divers on the boat and the old ones! The dive guides are very competent and professional, the only problem I have ever had was with triggerfish.

I still try to do 2 trips a year on the MV Scuba Cat, both to the Similans and Racha Yai. Although I have been on MV Scuba Fun day trips and MV Scuba Adventure, I prefer the MV Scuba Cat with its large dive deck and open plan design.

10 trips and 500 dives later, having seen many other companies and their boats, Scuba Cat is the only company who I would book with and I have no intention of changing.”

"Rob"

5 days and counting……………………See you again next week