WHITETIP REEF
SHARK
Order Carcharhiniformes
Family Carcharhinidae
Genus - Triaenodon
Species - obesus
Habitat
The whitetip reef shark typically lives along the bottom in clear, shallow waters surrounding coral reefs. It
has been reported at depths to 1,083 feet (330 m). Rarely coming to the surface, this shark is capable of lying
motionless on the bottom substrate for long periods of time. During daylight hours, whitetip reef sharks form
aggregations in caves, sometimes appearing stacked up like a pile of logs. The same sharks often return
repeatedly to the same cave for long periods of time, changing location only periodically. The whitetip reef
shark is most active throughout the night. Site fidelity is strong with each shark maintaining a small home
range for months or years at a time.
Biology
whitetip reef shark illustration
FAO Species Catalog, Vol. 4 Part 2 Sharks of the World
· Distinctive Features
This small shark is relatively slender with a broad flattened head. The snout is broadly rounded and
eyes are horizontally oval. Along with a down-slanted mouth, the prominent brow ridges give this
shark a permanent "disgusted" expression to its face. The first dorsal fin originates well behind the
free rear tips of the pectoral fins. The second dorsal fin is large, but smaller than the first dorsal. The
pectoral fins are broad and triangular in shape. The anal fin is about as large as the second dorsal fin.
There is no interdorsal ridge and lateral keels on the caudal penduncle are lacking.
Coloration
The whitetip reef shark earns its common name for the distinct white tips on the first dorsal and upper
caudal fins. The body is dark gray to brownish, fading to a light ventral surface. Small dark spots may
be present over the entire body. The remaining fins may also have white tips, however this may not
always hold true.
There may arise some confusion between the whitetip reef shark and the silvertip shark (C.
albimarginatus). The silvertip shark is a much heavier species with a large first dorsal and a much
smaller second dorsal fin. Also, its caudal fin is lined with white rather than tipped as in the whitetip
reef shark.
·Dentition
The tricuspid teeth each have one large triangular cusp in the middle along with two smaller ones on
either side.
·Size, Age, and Growth
The whitetip reef shark grow to a maximum length of just under 7 feet (2.13 m), however individuals
are rare at lengths over 1.6 m (5.25 feet). Males mature at about 3.4 feet (1.05 m) and generally reach
5.5 feet (1.68 m) in length. Females reach maturity at 3.4-3.57 feet (1.05-1.09 m) and grow to at least
5.18 feet (1.58 m). This species is known to reach a maximum age of at least 25 years.
· Food Habits
This shark is a specialist in capturing bottom-dwelling prey in caves and crevices, feeding primarily
on octopus, lobsters and crabs. It also feeds on bony fishes including eels, squirrelfishes, snappers,
damselfishes, parrotfishes, surgeonfishes, and triggerfishes. During the night, this shark becomes
very active, searching for prey items along the bottom substrate. When a prey item is located, the
shark will pursue it into a crevice and jam itself in after it. The tough skin, slender build, blunt snout,
and protective eye ridges make it possible for the whitetip reef shark to hunt successfully within these
very small spaces.
· Reproduction
During mating, the male whitetip reef shark lies next to the female, using his mouth to hold on to her
pectoral fins. This is followed by the male inserting one of his claspers into her genital opening,
releasing sperm. Fertilization occurs internally, resulting in 1-5 embryos. These embryos are
nourished via a placenta-like attachment to the mother during gestation. After an approximately 5
month gestation period, a litter of 1-5 pups is born with each pup measuring 20.5-23.6 inches (52-60
cm) in length. Mating and birth occur during varying seasons and is dependent upon location. At
Enewetak Atoll, birth occurs during autumn and winter while in French Polynesia it occurs during the
summer months.
Tiger sharks and other large piscivorous fishes prey on the whitetip reef shark
© Klaus Jost
· Predators
Predators of the whitetip reef shark include large piscivorous fishes such as the tiger shark
and giant grouper.
Parasites
The copepod Paralebion elongatus is a parasite reported from whitetip reef sharks caught in
Hawaiian waters.
Importance to Humans
The whitetip reef shark is fished in the waters off Pakistan, India, Sri Lanka, and Madagascar. Although
data on the commercial fishery involving this shark are lacking, it is also probably fished in other waters
throughout its range. It is caught with floating and bottom gillnets and longlines. The liver and flesh is
marketed for human consumption, although it has been reported to cause ciguatera poisoning.
Whitetip reef shark in waters off the coast of Borneo
© George Ryschkewitsch
Danger to Humans
This shark is relatively harmless to humans due to its easygoing disposition and small teeth. It avoids close
contact with humans, swimming off when approached by swimmers and divers. Often attracted to food,
divers have been able to hand feed individual whitetip reef sharks. However, on occasion, a shark will
become overly excited by spearfishing or when bait is present, resulting in a bite to a diver. This species is
also known to bite if harassed.
In Hawaii, some families regarded this shark as 'aumakua', a guardian spirit. They would feed rather than
hunt whitetip reef sharks.
Conservation
The whitetip reef shark is currently listed by the World Conservation Union (IUCN) as "Near Threatened" at
this time. The IUCN is a global union of states, governmental agencies, and non-governmental organizations
in a partnership that assesses the conservation status of species. Due to restricted habitat and depth range as
well as small litter size and late age at maturity, this shark may become threatened with increasing fishing
pressure.