Thresher Shark Divers’ final PADI IDC of 2011 has finished with yet another very happy PADI Open Water Scuba Instructor !! Ryan flew into Malapascua Island a couple of weeks ago as a PADI Divemaster, and has now flown back to Qatar as a very happy PADI Instructor eager to find his first students !!
After arriving in the Philippines, and making the short trip from Cebu City up to Malapascua Island, Ryan got straight into the water for a Skill Circuit, before hitting the classroom for the start of the IDC proper. After a couple of presentations from myself, it wasn’t long before it was time for Ryan to take centre stage and deliver his Knowledge Development presentations and teach us all about the PADI RDP…
Following some very good presentations in the classroom, it was soon time for Ryan to try his hand at teaching in the water too. Throughout the IDC, and indeed the IE, Ryan recorded some very strong scores…
We also found plenty of time to conduct some dives towards Specialty Instructor ratings and to complete EFR Instructor training for Ryan. We completed Specialty Instructor training in Deep, Wreck, Nitrox, Equipment, Night and Navigation specialties. On a couple of mornings we got up nice and early to venture out to Monad Shoal to dive with Malapascua’s most famous residents – the thresher sharks…
We had a great two weeks during the IDC, then we headed down to the city for the PADI Instructor Exams. Throughout the two-day examination process, Ryan excelled himself with some outstanding scores – including a few perfect 5.0 scores !! At the end of the two days, Ryan got the all important handshake from PADI Examiner George Wegmann, and then it was time to celebrate…
Thresher Shark Divers, on beautiful Malapascua Island in the Philippines, still has spaces on the PADI Instructor Development Course (IDC) scheduled to start on 11th October 2011.
Our dedicated IDC team of experienced PADI Professionals will be there to support you from the moment you arrive at Thresher Shark Divers to the moment you leave.
Our PADI Instructor Courses have been developed to make our candidates well-rounded PADI Instructors who can work anywhere in the world.
You will gain knowledge in areas as diverse as risk management, teaching children, hands-on experience of the business of diving, and PADI standards & procedures. There will also be lots of practical teaching workshops plus PADI Specialty Instructor training…
Upon successful completion of the PADI Instructor Exam (IE) you will be a certified PADI Open Water Scuba Instructor!
You must be a qualified PADI Divemaster (or equivalent)
Minimum 100 logged dives
Successfully completed a sanctioned CPR & First Aid Course in the last 24 months
The genus and family name derive from the Greek word alopex, meaning fox. Indeed the long-tailed thresher shark, Alopias vulpinus, is named the fox shark by some authorities. The common name is derived from a distinctive thresher-like tail or caudal fin which can be as long as the body of the shark itself.
Thresher sharks are large lamniform sharks of the family Alopiidae. Found in all temperate and tropical oceans of the world, the family contains three species all within the genus Alopias.
Alopias pelagicus – Pelagic thresher
Alopias superciliosus – Bigeye thresher
Alopias vulpinus – Common thresher
Distribution and habitat
Although occasionally sighted in shallow, inshore waters, thresher sharks are primarily pelagic; they prefer the open ocean, venturing no deeper than 500 metres (1,600 ft). Common threshers tend to be more common in coastal waters over continental shelves. In the North Pacific, common thresher sharks are found along the continental shelves of North America and Asia. They are rare in the Central and Western Pacific. In the warmer waters of the Central & Western Pacific, bigeye and pelagic thresher sharks are more common
Anatomy and appearance
Named for, and easily recognised by, their exceptionally long, thresher-like tail or caudal fins (which can be as long as the total body length), thresher sharks are active predators; the tail is actually used as a weapon to stun prey. By far the largest of the three species is the Common thresher, Alopias vulpinus, which may reach a length of 6.1 metres (20 ft) and a weight of over 500 kilograms (1,100 lb). The Bigeye thresher, Alopias superciliosus, is next in size, reaching a length of 4.9 m (16 ft); at just 3 m (10 ft), the Pelagic thresher, Alopias pelagicus, is the smallest.
Thresher sharks are fairly slender, with small dorsal fins and large, recurved pectoral fins. With the exception of the Bigeye thresher, these sharks have relatively small eyes positioned to the forward of the head. Colouration ranges from brownish, bluish or purplish gray dorsally with lighter shades ventrally. The three species can be roughly distinguished by the main colour of the dorsal surface of the body. Common threshers are dark green, Bigeye threshers are brown and Pelagic threshers are generally blue. Lighting conditions and water clarity can affect how any one shark appears to an observer, but the colour test is generally supported when other features, such as fin alignment, are examined.
Pelagic schooling fish (such as bluefish, juvenile tuna, and mackerel), squid and cuttlefish are the primary food items of the thresher sharks. They are known to follow large schools of fish into shallow waters. Crustaceans and the odd seabird are also taken.
Thresher sharks are solitary creatures which keep to themselves. It is known that thresher populations of the Indian Ocean are separated by depth and space according to gender. All species are noted for their highly migratory or ‘oceanodromous’ habits. When hunting schooling fish, thresher sharks are known to “slap” the water, herding and stunning prey. The elongated tail is used to swat smaller fish, stunning them before feeding. Thresher sharks are one of the few shark species known to jump fully out of the water making turns like dolphins, this behaviour is called ‘breaching’.
No distinct breeding season is observed by thresher sharks. Fertilisation and embryonic development occur internally; this ovoviviparous or live-bearing mode of reproduction results in a small litter (usually 2 to 4) of large well-developed pups, up to 150 cm at birth. The young fish exhaust their yolk sacs while still inside the mother, at which time they begin feeding on the mother’s unfertilized eggs; this is known as ‘oophagy’.
Thresher sharks are slow to mature, males reaching sexual maturity between 7 and 13 years of age and females between 8 and 14 years in bigeye threshers. They may live for 20 years or more.
All three thresher shark species have been recently listed as vulnerable to extinction by the World Conservation Union (IUCN).
Where can they be seen ?
Monad Shoal near Malapascua is a sunken island at 18-24m whose sides drop off to 230m. The thresher sharks live and hunt in this deep water for most of the day, but in the early morning, before it gets too light, they come up to the Shoal, attracted by its cleaning stations. Here they have a symbiotic (mutually beneficial) relationship with the small fish called cleaning wrasse which eat dead skin and bacteria from the shark’s body, its gills, and even inside its mouth.
After an entertaining day in the classroom, Fiona, Roh, Joseph and Tony can now call themselves EFR Instructors. They all did a great job at teaching skills and passed the exam with ease, and are now ready to educate the masses to help others in times of need…
We all thoroughly enjoyed playing with dolls and learning about the ins & outs of teaching the Emergency First Response course, and everybody is now ready to continue with the PADI IDC Prep course tomorrow.
In the morning we will be heading out into Confined Water for a ‘Control Workshop’, before making our way back to the classroom in the afternoon to sit the old PADI Divemaster exams…
Over the last few days, Divemaster trainee Lou has also completed her PADI Enriched Air and Deep Specialty courses with me.
We’ve had some excellent dives. The highlight for me was the first dive at Monad Shoal. About twenty minutes into the dive we had an excellent thresher shark encounter. A beautiful female shark was circling in front of us, being attended to by the local cleaner wrasse.
After about ten minutes or so she returned to the depths. This also signalled the end of the no-decompression limits for the air divers. Whilst those guys were on their way back to the line for their ascent, we were also graced by the presence of a huge manta ray. It swooped slowly in for a leisurely loop around the cleaning station before heading back out into the blue…
We were also fortunate enough to see three thresher sharks the following morning during our 40m dive. One at the very beginning of the dive before we reached our maximum depth, so I wasn’t sure if Lou’s big smile was shark or nitrogen narcosis induced. The other two were circling a cleaning station a little later in the dive. As we were diving on air for this dive, we ended up having to leave them to their cleaning ritual and head to the ascent line happy, but wishing we had a little more bottom time available…
In the next couple of days we’ll also be starting the PADI Wreck Specialty…