捍卫鲨鱼

Many sharks are the top predators of the marinE食品链，包括大白鲨，虎鲨，蓝鲨，马科鲨鱼和锤头鲨。这些关键物种指导地球上整个海洋生态系统的功能和健康。如果没有鲨鱼，鱼类和无脊椎动物，人口将失去疾病和人口过多的平衡。鲨鱼有助于使猎物人群保持最佳进化形状，从而消除了弱者和患病。人类对鲨鱼的持续大规模杀害有助于生态系统的失败，类似于大地掠食者被摧毁时看到的问题。仅服用鲨鱼的鳍的残酷做法是为了摧毁全球鲨鱼种群。

鲨鱼是古老的生物。有些人认为最古老的鲨鱼的化石可以追溯到超过4.2亿年。这是中期的时代，当时jaw和骨鱼首先进化，包括鲨鱼。当时在土地上，只有小苔藓植物开始发展。鲨鱼的多样性1zplay确实扩大了大约1亿年前。当其他物种死亡时，在6500万年前的众所周知的灭绝时期，鲨鱼成功地使他们的进化步伐在时间上游泳。著名且巨大的70英尺长Megalodon大约在150万年前灭绝了。这家巨人在海洋中统治了近2500万年。There are now about 470 known shark species on Earth, the largest being the gentle giant, the Whale Shark, reaching up to 40 feet in length. This animal, found in tropical and subtropical waters worldwide, is amazing to scuba or snorkel with.

The fear of sharks is engrained in the modern human mind, mostly due to Hollywood films such as the classic Jaws. Fear and awe of the powerful and unknown keeps the American couch potatoes glued to their TV's watching documentaries about the ocean and the yearly bout of Shark Week on the Discovery Channel. The awareness and truth about sharks is a mixed sack of love and hate.

The best documentary, in my opinion, in the genre of shark-related films is still鲨鱼水. Released in 2006,鲨鱼水is a powerful and beautifully filmed documentary that opens your eyes to the struggle of the worldwide shark population. The movie is disturbing and inspirational -- the cinematography is amazing.

As a recreational scuba diver and snorkeler, I have swam with many sharks and while always fascinated, I do not fear them. Sharks are big fish who react to movement or a knife's clank on a scuba tank, just like most fish do. The only time I was afraid was on a drift dive off Cay Sal Bank, Bahamas. A large Hammerhead shark swam directly towards my mom. Once it was within several yards it suddenly darted away in its typical 180-degree motion and went back into the darkness along the wall we were drifting along. The Common Nurse shark is also completely harmless, while Reef sharks are common, beautiful, and skittish. The most dangerous creatures of the sea that I have experienced so far, as a scuba diver, were a swarm of baby jellies. A much more tangible danger of scuba diving than sharks is lack of training or careless practice.

Sharks are one of the most exciting parts of scuba diving! However, I have intentionally sat out shark dives where dive instructors chum the waters with bloody fish to attract in the sharks for a show. I sipped a margarita on deck as my fellow dive buddies descended through the frenzy. They rested on their knees in a circle around the action and returned to the surface, exhilarated and safe. Swimming in a sea of chummed blood may be pushing it a bit too far but I have not personally heard of anyone getting hurt or bitten, even the dive masters in the heart of the frenzy make it out with all limbs.