Marine Biology: Power Boat Adventure Conclusion (4/25/13)

After we fed the sting rays, we watched the guide feed the sharks. There were three kinds of sharks: nurse sharks, Caribbean reef sharks, and lemon sharks. Nurse sharks (Ginglymostoma cirratum) are bottom dwellers and often are found in reefs. They often live in shallow water, about 3 feet deep, but they can be found as deep as 246 feet. The are slow-moving sharks that can lay still on the ocean floor. They are harmless to humans, so don't be worried. They are usually 8 to 10 feet long, but can get as large as 14 feet long. They typically weigh 200 to 330lbs.

The next kind of shark we saw is the Lemon Shark (Negaprion Brevirostris). It is 8 to 10 feet long and weighs about 200 lbs. It is also a bottom dweller that lives near reefs. Like the nurse shark, it is not harmful to humans. The Lemon shark because is gives off a lemon scent to attract its prey. It survives well in captivity. It is a social animal and is often seen in groups. It has also been studied a lot.

The Caribbean Reef Shark (Carcharhinus perezi) was the third kind of shark we saw. It is the most common shark in the Caribbean Sea, but it is classified as Near Threatened, just like the Lemon Shark. This is partly because they live and feed in coral reefs which are being destroyed. They have been seen resting motionless, which is unusual for a shark. It also lives near reefs like the other two sharks we saw. They are usually about 6.5 to 8 feet long, but the longest record for one was 10 feet. They can get up to 154 lbs, which is the record for the heaviest. They are normally shy of humans, they are harmful only when they are provoked, which can be because food is near.

All these sharks live in coral reefs. We snorkeled over one coral reef. Coral reefs are colonies tiny marine animals called corals. They live in colonies and look like a bunch of small sticks. The reefs are hard because they are made out of calcium carbonate, which the corals excrete. The coral reef is nicknamed "the rainforest of the sea". Coral reefs are some of the most diverse ecosystems on Earth. They are home to 25% of all marine animals. The coral reefs are usually found in shallow depths in tropical waters, but can exist in deep water and cold water. The fragile ecosystem of the coral reef is so fragile because it is sensitive to water temperature. It is being destroyed by global warming and water pollutions.

Here are some photographs of the sharks we saw. We do not know how to distinguish them from each other. I have photographs of the coral, but it is on a disposable underwater camera, and we do not have a way to develop the film yet.