Blacktip reef sharks are elegant, eye-catching sharks that are abundant predators throughout the shallow waters of the Indo-Pacific.
They aren’t the biggest or fastest sharks in the water, but that doesn’t stop them from performing incredible aerial performances.
The blacktip is one of the few shark species known to jump out of the water, performing a behavior known as breaching.
We might not know why blacktip reef sharks breach, but we do have a few more interesting facts about them that we’d like to share with you.
Why not pull up a chair, and enjoy this insight into the life and characteristics of one of the most common sharks in South Florida?
What do Blacktip Reef Sharks Look Like?
Blacktip reef sharks have distinctive black tips or margins on the ends of their fins, underneath which are bands of white that emphasize the black markings.
As they prefer shallow water, they frequently swim with their distinctive dorsal fin exposed.
Beyond their black tips, these reef sharks look similar to any other shark, with their brownish-grey backs and white underbellies. This coloration camouflages the shark from above and below, which is why it’s so common.
The blacktip reef shark has a streamlined muscular body and large, sickle-shaped pectoral fins. A short, wide snout protrudes in front of its oval eyes, underneath which is the shark’s mouth.
Blacktip reef sharks have narrow teeth in their upper jaws and serrated ones on the bottom. These enable the blacktip reef shark to hold onto its slippery prey and “cut into it much like a steak knife.”
Although the blacktip reef shark (Carcharhinus melanopterus) has much in common with the oceanic blacktip shark or Carcharhinus limbatus, the two species rarely cross paths.
As their name suggests, the blacktip reef shark prefers warm reef waters, while the oceanic can tolerate the cooler temperatures of the open waters.
Blacktip Reef Sharks Taxonomy
When French naturalists first discovered the blacktip reef shark in the early 1800s, it was considered to be a member of the Carcharias genus. It was later moved to the Carcharhinus genus and all other types of requiem shark.
Like other types of requiem shark, the blacktip is a strong swimmer that prefers warm tropical waters and gives birth to live young.
The blacktip reef shark’s scientific name refers to its black-tipped fins, with the word “melanopterus,” coming from the Greek words “melas,” meaning “black,” and “pteron” meaning “fin” or “wing.”
Blacktip Reef Sharks’ Characteristics
The blacktip reef shark is a relatively small species of shark that reaches a maximum length of around seven feet. Male blacktip reef sharks reach maturity once they’re around 3.4 feet long, whereas females wait until they exceed four feet.
By comparison, the oceanic blacktip reef shark is slightly larger, with the males maturing at 5.9 ft and females at around 6 ft.
The blacktip reef shark’s characteristic behavior distinguishes it from its larger cousin. It frequents shallow water where it can be seen swimming with its dorsal fin exposed.
Rarely entering waters deeper than around 65 feet, blacktip reef sharks are often seen close to shore, where they gather in small groups.
An active and fast-moving species, the blacktip reef shark is faster during the day, possibly because the cooler water “reduces their metabolism” at night. Although the top speed of the blacktip reef shark is unknown, researchers have found that some populations tend to be more mobile than others.
The blacktip reef shark gets oxygen from ram ventilation, which means it must keep moving to breathe.
Like other species of requiem sharks, it has a third eyelid, known as a nictating membrane, that helps protect the eye during an attack.
Blacktip Reef Shark’s Life Cycle
The blacktip reef shark is a viviparous species of shark that gives birth to litters of between two to five pups.
The eggs are fertilized internally after a brief period of courtship. To copulate, “the male pushes the female on her side and positions her so her head is against the bottom and her tail is raised.”
This behavior is presumably designed to make it easier for the male to insert his clasper into her cloaca and complete the fertilization process.
The gestation period appears to vary according to habitat, with females off the coast of north Australia giving birth after just seven to nine months, while those in the Indian Ocean and Pacific islands take 10 to 11 months.
Scientists believe the difference in gestation periods is probably due to the warmer waters off the coast of Australia.
Females give birth in shallow nursery areas protected by coral reefs. Their pups are relatively small at birth, measuring between 13 and 20 inches long. They are free-swimming and independent from the moment they’re born and grow rapidly for the first couple of years of life.
Pups and juvenile blacktip reef sharks congregate in shallow water over sand flats or in mangrove swamps close to shore.
Blacktip reef sharks take between eight and nine years to reach sexual maturity, which gives them limited opportunity to reproduce. The average lifespan of the blacktip reef shark is estimated to be between 10 and 13 years, meaning their reproductive life may only last a year or two.
Where do Blacktip Reef Sharks Live?
Blacktip reef sharks have a wide global distribution, appearing in shallow coastal waters throughout the Indo-Pacific region. It has also “colonized the eastern Mediterranean Sea by way of the Suez Canal.”
While juvenile blacktips prefer shallow, sandy flats, adult blacktip reef sharks “are most common around reef ledges and can also be found near reef drop-offs.”
Juvenile blacktip reef sharks often congregate in shallow water that barely covers their bodies, while adults occasionally venture into deeper waters up to 246 feet deep.
Blacktip reef sharks aren’t as migratory as their open-ocean cousins and show more site fidelity than many other shark species, spending “~70% of their time within an area 0.3 ㎢.”
This tendency to remain within a specific territory makes the blacktip reef shark popular among divers and snorkelers. The best places to dive with these non-aggressive sharks include the Maldives and Koh Tao, off the southern coast of Thailand and Bora Bora.
Blacktip Reef Sharks’ Behavior
Blacktip reef sharks might be popular amongst scuba divers, but they’re not particularly easy to approach. Generally shy and skittish, the blacktip reef shark rarely attacks humans.
If there’s food involved, however, the blacktip can become more courageous but is rarely aggressive.
The blacktip reef shark is a social creature, forming loose groups that scientists believe may offer protection against predators and present cooperative hunting opportunities.
Studies suggest that blacktip reef shark group together for social reasons, as well as environmental ones. They appear to seek out the company of specific individuals while purposefully avoiding others.
Blacktip reef sharks often hunt together, working collectively to secure their prey. Like the one captured in this video, they are one of the most likely species to engage in feeding frenzies.
Groups of blacktip sharks have been filmed herding schooling fish into tight groups or chasing them into shore.
During their high-speed pursuits, blacktip reef sharks leap out of the water, often spinning through the air before splashing back down.
While some researchers suspect that this breaching behavior is an unintended result of “the momentum a shark builds during a speedy charge,” others suggest it could be a form of courtship display.
Blacktip reef sharks have also been observed spy-hopping – a behavior more commonly associated with whales.
When spy hopping, the shark positions itself vertically in the water, with its head or eye above the surface.
It’s a relatively common behavior for great whites and could be a hunting behavior or “a tool for curiosity and investigation.”
What do Blacktip Reef Sharks Eat?
The favorite food of the blacktip reef shark is, unsurprisingly, fish. Unlike other sharks that specialize in hunting marine mammals, the blacktip reef shark’s diet consists primarily of schooling fish like groupers, mullet, grunters, and jacks.
The sharks catch mullet by herding them onshore and ambushing them while stranded. This is a dangerous hunting method for an animal that needs water to breathe, but it’s clearly worthwhile.
Although blacktip reef sharks prefer fish to almost any other food, they have been known to sample some strange alternatives, including algae, coral, “and even rats!”
Blacktip sharks will also eat cuttlefish, octopus, squid, and shrimp, although such behavior is rare.
Around the Palmyra Atoll, blacktip reef sharks also predate seabird chicks that have fallen out of their nests.
Like most sharks, the blacktip reef shark has average eyesight, lacking the cones that enable us to discriminate color and details. Instead, the shark’s “vision is adapted for sensitivity to movement or contrast under low light conditions.”
The blacktip reef shark can also detect electrical currents in the water and uses the ampullae of Lorenzini to locate prey.
What Hunts Blacktip Reef Sharks?
As pups, blacktip reef sharks need protecting, which is why the females give birth in such shallow waters. Larger sharks can’t access those waters, making them safe havens for youngsters.
Even as they mature, blacktip reef sharks could easily be seen as a decent meal by other sharks like the tiger or great white.
Orcas are also formidable predators that appear to expand their menus to incorporate blue whales and great white sharks. The only reason for orcas to spare the blacktip reef shark is their habitat keeping them at bay.
Little can stop humans once they set their sights on something, and the commercial fishing industry has targeted the blacktip reef shark for hundreds of years. Although they are utilized for their fins, liver oil, meat, and skins, they “have limited commercial value due to their small size.”
The commercial fishing industry’s use of gill nets also endangers the blacktip shark as they get entangled in the nets, causing potentially fatal injuries. Anglers also target blacktip reef sharks as a game fish.
Conclusion
The blacktip reef shark is one of the most common species in its habitat. It’s not particularly large or threatening and is more likely to flee from human contact than attempt to attack.
Despite that, there have been a few attacks over the years, including one off Florida’s Daytona Beach in July this year, and experts believe blacktip reef sharks are responsible for “most of the bites” in the area.
Generally timid, the blacktip reef shark is a favorite among divers as it is predominantly non-migratory and stays close to the area in which it was born.
Although blacktip reef sharks aren’t currently endangered, they are vulnerable to population decline due to overfishing and habitat destruction.
Nicky is a British adventurer and animal lover who spends her time exploring the natural world and writing about her experiences. Whether on horseback, underwater, running, hiking or just standing with a fishing rod in hand, she embraces everything her adopted home of South Africa has to offer.