I was training for a triathlon off Gulf Shores, right here in Alabama. A group of about 15 to 18 of us had met on the beach on June 9, 2000 - a date I will remember for eternity.

We planned to do a one-and-a-half-mile swim followed by a 35-mile bike ride, but the water was quite rough that morning. Two of us - probably the strongest swimmers in the group - decided to go out and test the water, to make sure the undertow was not too overwhelming.

We were about 125 yards from the shore, swimming east to west, when I looked at my watch; it was 6.38am. I took two more strokes and was hit from below by an eight-and-a-half-foot bull shark. It hit my thighs and nearly knocked me clear out of the water on to my back. I put my face back under the water and saw it shooting towards me again.

I instinctively put my hands out in front of me and it took all four fingers from my right hand. There was no pain whatsoever at this stage - just a massive desire to survive. There was blood all around me. I tried to back-paddle, using just my left hand, when he hit me for the third time, bang in the stomach. It left a scar two-and-a-half inches deep on my stomach.

The fourth time, I saw the fin coming towards me through the water. I tried to push him off with my hands and he grabbed my arm and took me down to the bottom - about 15 feet.

My arm was still in his mouth as he went into a feeding frenzy, shaking his head back and forth. The spectators on the beach said I was down there for about two minutes, being slung around like a rag doll. My back, shoulder and right hip were sandpapered raw by the sea floor.

It’s down there that I had a candid conversation with the good Lord. I asked him for help and made some promises in return. What those promises are remain between me and the good Lord, but I thank Him every morning and night.

Eventually, the shark brought me up to the surface and pushed me all the way to the beach. People said it was like I was on skis. I felt my feet touch a sand bar and I wiggled and kicked until I managed to jerk my arm out of his jaw.

It is called “degloving”: the shark had stripped everything - all the skin and tissue - off the bone. There was nothing from the elbow down. The shark was never found, but if it was, it would have a Timex Ironman in its stomach that goes off at 5.30 each morning.

I fell backwards and ran on to the beach. My friend Karen found me laughing, saying: “I’m alive”. I spent 13 days in intensive care, including several days in an induced coma.

I must have been trying to suck all the oxygen out of the water because my lungs were full of sea water. It meant I had an infection that saw my temperature rise to 105 degrees for three days.

But I was out of hospital 15 days later and was doing my first triathlon nine months later. I was back in school on the first day of term because it was important to show the students how important I think education is - I did not take a day off.

I still get lots of inquisitive looks and questions from the young people here but I am very willing to share my story. I may not have a right arm, but they see that I can still do everything I want in life.

I try to educate people that the ocean is a beautiful place that should not be feared. I do not want to leave a legacy of negative feelings towards sharks, either. They are extremely important to the oceans I love so much. I have made it my mission to help leave that ocean the same way I found it.

Chuck Anderson, 55, is principal of the Central Baldwin Middle School in Robertsdale, Alabama, US. He supports Pew Environment Group, a shark conservation group. He was talking to Hannah Frankel.