… of abject violence, death, and being something close to a social animal. But it usually pulls back at the last minute.
If you’ve been lucky enough to explore a beautiful Indo-Pacific reef, chances are you’ve encountered one of these sleek, caramel-coloured sharks with black-tipped fins. Failing that, it’s a common sight in your local aquarium, being sharky enough to look cool, but not dangerous enough to snack on a human limb. Ninety-nine percent of the time.
Like other sharks equipped with triangular and serrated teeth, the blacktip reef shark snacks on the other fish, squid and crustaceans skittering about in the shallows, and is even partial to sea and terrestrial snakes.
How it can possibly get hold of the latter, I’ll come to later, but as well as its keen sense of smell it uses the usual shark equipment, ampullae of Lorenzini, to detect electrical fields in the water. When hunting, however, it’s cruising for just as much of a bruising.
Strike or psych?
Both individually and in groups, it’s been seen chasing fish shoals from below, driving them towards the surface before leaping, spinning, and splashing back down again. One lucky photographer in Australia also caught a group beaching on land after herding fish towards the shore. It’s energetic to say the least, and has a habit of psyching out animals it probably isn’t even going to attack.
In parts of Palau, Micronesia, it’s known as “matukeyoll”, which comes from the expression “to dash at and turn quickly”. It seems the blacktip reef shark, in its curiosity, will sometimes rush divers, fishermen, and Berlin Zoo aquarium handlers at about 30km (18 miles) an hour before turning away at the very last minute. And if you’re wading and/or surrounded by fishing gear, meat or any kind of blood, from time to time it leaves it a bit too late.
There have only been 11 unprovoked blacktip reef shark attacks on humans since 1959, which is good going considering how often we come into contact with them. Most of them didn’t end in serious injury, such as a small nick from catching one of its fins, but in the 1970s, one unlucky Palauan fisherman lost a chunk of calf muscle and was left with a limp, even after a two-hour surgery.
There are a couple of theories as to why the sharks attacked: when someone is wading rather than fully submerged, it’s harder for the shark to identify this bizarre and possibly tasty moving thing in the water, or it may have felt cornered. The attacks weren’t sustained either, suggesting a case of mistaken identity or extremely bad taste. It’s not their only potentially violent interaction though.
Depending on the region, male and female blacktip reef sharks prefer to live separately, with the females congregating in the shallow reefs with the kids, and the males roughing it further out. In the breeding season, a female will be tail-gated by one or more males, until eventually one of them grabs her frontal fin, pushes her downward, and uses his claspers to “embrace” her for some clumsy mating. Unsurprisingly, this can leave her with a scar or two, but I’ll come back to this later.
The jury’s out as to how long the pregnancy lasts, and whether smaller females get busy every two years instead of every year, but the birth doesn’t seem all that great either. Blacktip reef sharks give live birth to about four pups, and according to some Palauan fishermen, they seek out a trailing mangrove branch – yes, they are sometimes found in coastal lagoons, hence the snake-snatching – or underwater logs, which they bump and grind against to help release each new arrival.
Said pups will stay in the shallow reef waters with the females for a while, until they’re big enough to brave the deeper open waters.
For those blessed with a crazy pattern, it’s probably wise to never move out. In their 2018 study, Bruckner and Coward discovered some baby blacktip reef sharks with autumnal blotches. We’re not sure if this was due to extensive inbreeding, as some atolls and reefs are quite isolated, but it’s never a good idea to stand out when there are so many other larger sharks on the prowl for a meal. But fret not, because the blacktip reef shark isn’t as delicate a waif as it might appear.
Sex injuries, big bites, boat strikes, and even missing fins have been shrugged off. In a study in French Polynesia, a shark sporting an almost ruler-length, gaping wound from a boat saw it closed within a month and entirely gone in 13.
Even more incredibly, a de-finned male was spotted two years later continuing his sharky business. As for the females, mating scars also tended to heal within four weeks. Despite its apparent invincibility, it’s still a small shark, so it makes sense for it to herd for protection. That’s not the only reason, though.
Not as shallow as it seems
It’s rare to find a blacktip reef shark on its own, especially if you’re a diver and therefore the most amazing thing it’s ever seen, and there’s evidence this is down to preference rather than just joining the biggest group “because predators”. In 2012, Mourier et al. found that some developed specific social and long-term bonds, something that had already been noticed in Hawai’ian folklore.
Due to congregating in the same group for most of its life, the blacktip reef shark is known as an ‘aumakua, a family’s guardian spirit or the reincarnation of a relative. As a result, it’s usually spared the hook or the plate.
It takes a special kind of shark to live in shallow, human-centric areas while also following and trolling them. The healing powers probably give it a sense of invincibility, but still, hats off to you, blacktip reef shark: there are far bigger predators out there in the sea, but you choose to greet and mess around with the absolute worst one.
Latin: Carcharhinus melanopterus
What? Grey to sandy-coloured reef shark with a white belly and black tipped fins.
Where? Shallow Indo-Pacific waters and their associated reefs, as well as the occasional coastal mangrove.
How big? Up to 1.8 metres / 6 feet long.
Endangered? Considered Near Threatened, as although it has a large range and isn’t over-exploited, it takes a while to reproduce.
Probable motto: I’m coming for you!…nah, just kidding.
They look cool. Do they need my help at all?
The blacktip reef shark is hunted for its meat, fins, and its liver oil, but apparently not in great enough numbers to make a dent. There aren’t any conservation drives at the moment, but its reef home could definitely use some love and attention.
Just to prove I’m not fibbing:
Bernal, Diego, and Lowe, Christopher G. 2015. “Field Studies of Elasmobranch Physiology” Fish Physiology 34(Part A):311-377.
“Blacktip reef shark“. No date. MarineBio.
“Blacktip reef shark“. No date. Maui Ocean Center.
“Blacktip reef shark“. No date. Monterey Bay Aquarium Foundation.
“Blacktip reef shark“. No date. National Aquarium.
“Blacktip reef shark“. No date. Oceanarium, the Bournemouth Aquarium.
“Blacktip reef shark“. No date. Waikiki Aquarium.
“Blacktip reef shark“. No date. Zoo de Granby.
Bray, Dianne J. No date. “Carcharhinus melanopterus“. Fishes of Australia.
Bruckner, A.W., and Coward, G. 2018. “Unusual occurrence of abnormal skin pigmentation in blacktip reef sharks (Carcharhinus melanopterus)“, Coral Reefs 37(2):389-389.
Carpenter, Kent E. No date. “Carcharhinus melanopterus (Quoy & Gaimard, 1824)”. FishBase.
Chilton, Gemma. 2016. “Rare photos of blacktip reef sharks ‘beaching’“. Australian Geographic.
Chin, Andrew. 2013. “The biology and ecology of the blacktip reef shark Carcharhinus melanopterus (Quoy & Gaimard, 1824) and implications for management“, thesis for James Cook University.
Chin, Andrew et al. 2015. “Blacktip reef sharks (Carcharhinus melanopterus) show high capacity for wound healing and recovery following injury“, Conservation Physiology 3(1):conv062.
“Hawaiian words for sharks“. 2008. In “Natural History of Sharks, Skates and Rays”. Powerpoint Presentation.
Helfman, Gene S. and Randall, John E. 1973. “Palauan fish names“, Pacific Science 27(2):136-153.
Heupel, M. 2009. “Carcharhinus melanopterus. The IUCN Red List of Threatened Species” 2009: e.T39375A10219032.
Johannes, R.E. 1981. “Words of the Lagoon: Fishing and Marine Lore in the Palau District of Micronesia“. University of California Press.
Mourier, Johann et al. 2012. “Evidence of social communities in a spatially structured network of a free-ranging shark species“, Animal Behaviour 83(2):389–401.
Press, Michelle. No date. “Blacktip reef shark“. Florida Museum.
Randall, John E., and Helfman, Gene S. 1973. “Attacks on Humans by the Blacktip Reef Shark (Carcharhinus melanopterus)“, Pacific Science 27(3):226-238.
“Sharks (Carcharhinus melanopterus)“. No date. Aquarium Berlin.
Featured image credit: “Blacktip Reef Shark Stock Photo” by Pascale Gueret.