iainwilliams
Contributor
Hello Number 1 here (check the first thread of this forum).
Im just back from the Philippines where I spent 4 weeks diving in several areas. My travels initially took me to Malapascua Island north of Cebu Island in the central region of the archipelago. The island is renown for the thresher sharks that migrate daily into shallow water at the top of reef for cleaning.
Conditions during my week were rough and 2-3 meter swells with strong winds were the norm. The depth to the top of the circular shaped reef was 25 meters and the reef dropped sharply to deeper depths. The water was a very green colour and visibility was between 7 18 meters due to plankton. Diving starts early at 0530 as the sharks move back into deeper water after the early hours.
I waited about 35 minutes for my first encounter, staring into the gloom wondering what on earth I was doing here feeling cold in a thermocline 4 degrees colder than the usual warm water! waiting. To occupy myself I watched nudibranchs, white anemones and three very colourful eels.
Then the thresher emerged out of the green swimming directly toward me. Its bulk was large and the black eye initially reminded me of diving with a white shark. At 5 meters distant the thresher moved to the right and swam past me. The shark was a large female approximately 3 meters in length (body only without tail), the unmistaken elongated upper caudal trailing behind her torso. The thresher then turned and swam back in front of me before turning once again and disappearing into the gloom.
All to soon the encounter was over, however, like all shark encounters of such magnitude the memory is permanently burnt on the retina!
Im just back from the Philippines where I spent 4 weeks diving in several areas. My travels initially took me to Malapascua Island north of Cebu Island in the central region of the archipelago. The island is renown for the thresher sharks that migrate daily into shallow water at the top of reef for cleaning.
Conditions during my week were rough and 2-3 meter swells with strong winds were the norm. The depth to the top of the circular shaped reef was 25 meters and the reef dropped sharply to deeper depths. The water was a very green colour and visibility was between 7 18 meters due to plankton. Diving starts early at 0530 as the sharks move back into deeper water after the early hours.
I waited about 35 minutes for my first encounter, staring into the gloom wondering what on earth I was doing here feeling cold in a thermocline 4 degrees colder than the usual warm water! waiting. To occupy myself I watched nudibranchs, white anemones and three very colourful eels.
Then the thresher emerged out of the green swimming directly toward me. Its bulk was large and the black eye initially reminded me of diving with a white shark. At 5 meters distant the thresher moved to the right and swam past me. The shark was a large female approximately 3 meters in length (body only without tail), the unmistaken elongated upper caudal trailing behind her torso. The thresher then turned and swam back in front of me before turning once again and disappearing into the gloom.
All to soon the encounter was over, however, like all shark encounters of such magnitude the memory is permanently burnt on the retina!
The Common Thresher Shark (Alopias vulpinus) is a shark whose tail fin has a greatly elongated upper lobe. This shark is a very strong swimmer and can even leap out of the water. The Common Thresher Shark is not an aggressive shark, but it can be provoked. The thresher's large tail can injure divers.
The Common Thresher Shark swims from the surface to a depth of about 1,150 feet (350 m). It lives in tropical and temperate waters, including the eastern and western Atlantic, the central Pacific, and the Indo-west Pacific. The Common Thresher is decreasing in numbers because of overfishing (it is hunted for meat and for its fins).
Anatomy: The Common Thresher has a countershaded body, dark blue-gray above and white underneath. It has small jaws, but can use its tail to corral and even kill fish. The first dorsal fin is much, much bigger than the second; the pectoral fins are curved. Like other mackerel sharks, it has an anal fin, 5 gill slits, 2 dorsal fins, no fin spines, the mouth behind the eyes, and no nictitating eyelids. The Common Thresher shark ranges from 16.5 to 20 ft (5 to 6 m) long.
Teeth and Diet: The Thresher eats s quid and fish, corralling them with its elongated tail; it catches prey with its very sharp (but small) teeth.
Classification: Kingdom Animalia, Phylum Chordata, Class Chondrichthyes, Order Lamniforms, Family Alopias (Thresher sharks), Genus Alopias, Species vulpinus.