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Today on Animal Fact Files we’re discussing blacktip reef sharks. These fish get their common name from how they look and where they live. It's pretty easy to tell blacktip reef sharks apart from other reef sharks because they have black-tipped fins. The black, especially on their dorsal fin, is surrounded by a white band that fades into the grey of the adult shark's back. Like many shark species, blacktip reef sharks display countershading in which their back is darker than their pale underside. This makes them more difficult to spot from above and below, which helps them hide from predators and prey alike.

It may be surprising to consider a shark as something that has to worry about predators, but blacktip reef sharks aren't the biggest fish on the reef. Lemon sharks and even great hammerheads take blacktip reef sharks as prey. Their young also have to watch out for large groupers! Blacktip reef sharks are about 1 foot (30 cm) long when born and reach reproductive maturity when they're just under 4 feet (122 cm) long. Females are larger than males at full size and can reach up to 6 feet (183 cm) long, although this is relatively rare.

As their name implies, blacktip reef sharks prefer reefs, and typically stay within close proximity to a home reef which they rarely leave over the course of their life. Although they do travel between reefs, crossing deeper waters from time to time, especially for breeding purposes, they generally remain in the same area. Females even have site fidelity for where they give birth– they prefer to return to the same place each time they have their babies.

Blacktip reef sharks can take upwards of eight years to reach sexual maturity, especially the females who have to reach a larger size before they're ready to reproduce. Plus, their mating can be aggressive. Males bite females during intercourse, so it's not uncommon to see these sharks with mating scars. Blacktip reef sharks give birth to live young which gestate inside their mother anywhere from 8 to 16 months depending on their location. There are 4 pups per litter on average, although as many as 14 pups are possible. They reach about a decade old on average.

True to their name, blacktip reef sharks are most commonly seen on reefs, staying in shallow waters typically no more than 330 feet (100 m) deep. They prefer clean, clear saltwater, but they're also able to enter turbid, oxygen deprived locations such as estuaries, lagoons, mangroves, and more. In fact, these sharks commonly gather in groups around these spots. This is the most common way humans face threats from these generally harmless fish. Blacktip reef sharks may bite people wading in shallow water, especially if the shark feels trapped or threatened. It's worth noting, however, that there have only been 11 documented unprovoked blacktip reef shark attacks on humans since 1959.

They're not out to eat people. Blacktip reef sharks much prefer fish including stingrays, crustaceans such as mantis shrimp, and cephalopods such as squids and other molluscs. They've been observed purposefully herding schooling fish towards the shoreline to trap them and eat them in abundance as the fish struggle to swim away. What's more, blacktip reef sharks are known to eat sea snakes and have even been documented trying to take a bite out of a green sea turtle. They're certainly tenacious, although generally not considered dangerous to humans.

Blacktip reef sharks range throughout the Indian and Pacific Oceans living from the eastern coast of Africa to the Hawaiian Islands and their surroundings. They're some of the most common sharks seen on reefs. They also live in the Red Sea and there are reports of them in the Mediterranean, however these are unsubstantiated and an established colony is not known from that locale.

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