The Blacktip shark is a common sight in many areas of the world, where it is regularly encountered by fishermen and divers alike. The species takes its name from the black markings on the tips of its dorsal, pectoral and lower tail fin, which is why it is so distinct and recognisable. Over the years though there have been several attacks on divers reportedly perpetrated by the blacktip, which has called some people to question its temperament, an whether it is a safe shark to be near in the water.
Most sharks that tend to be dangerous or at the very least potentially dangerous tend to be species that feed on large marine mammals or fish. The tiger shark, great white and bull sharks being among the most dangerous species for example all eat almost anything that they can catch and bite. Less dangerous species tend to eat smaller fish, often taking them from shoals, or crustacean species from the sea floor. So the idea of the blacktip being dangerous given that it eats small fish mainly seems odd.
The blacktip shark (Carcharhinus Limbatus) is often confused for either the Spinner shark (Carcharhinus Brevipinna) or the Blacktip Reef Shark (Carcharhinus Melanopterus). The true blacktip is the largest of the three species however, and also the most likely to nip the unwary diver who gets too close. Some attacks attributes to the blacktip might have been due to either of these other species as well however. Despite the fact that they are both relatively harmless unless provoked, and are both smaller than the blacktip.
The fact that they are so commonly seen by divers, and because they tend to swim in tropical, shallow water means that attacks are bound to happen. Many of these are inexperienced divers who are learning how to dive and may also tend to splash around and generally inadvertently get too close to the sharks. Experienced divers usually consider blacktip sharks to be virtually harmless however.
In reality most species of sharks can give a painful bite if they are provoked or if they mistake you for food. Even species incapable of growing to more then a few feet long can and will bite on occasion, and the difference between a nasty bite and being potentially dangerous is a fine line. That being the case the blacktip being able to reach lengths of up to 9 feet means that it can potentially be a threat to life and not just give a nasty bite.
The reason that some have speculated that blacktip sharks have a nasty temperament is because they have a habit of becoming agitated when food is present. Like many species of sharks groups of blacktips will often become aggressive when food becomes present. Fighting over food and carrion and often being more aggressive towards anything else in the water, including divers. Fish can detect that the sharks are agitated or aggressive and will then either hide or leave the immediate area. Divers however often can't detect these same signals, which is why they often run the risk of being bitten or attacked.
Generally speaking blacktip sharks are not aggressive to divers and of the thousands of encounters that they have with people every day attacks are very rare. That being said they do have the potential to become dangerous when food is present or if they are provoked. A good rule with any large wild animal is to just keep your distance, and if they become agitated then to leave the area immediately. The mistake most people who are attacked make is to stay in the water after they have been warned by the sharks body language that it might bite.