One of the most notorious shark species, tiger sharks can be found in the Red Sea, though they are less commonly seen by divers than some other reef associated species. Found globally in tropical and subtropical waters, in the Red Sea, tiger sharks are most often sighted around Tiran Reefs, Strait of Gubal, Safaga, Rocky Island, St.John Reefs and Elphinstone dive sites.
Tiger Sharks - Galeocerdo cuvier
Tiger sharks belong to the order Carcharhiniformes and is the only extant species within the genus Galeocerdo. There are however a number of other extinct species of tiger shark that have been identified from fossilised teeth. Both extant and extinct tiger sharks have relatively unique dentition which can be used to identify them. G. cuvier teeth are short and wide with a double serrated edge that enables them to slice through flesh, bone and turtle shells.
One of the most obvious identifying features of tiger sharks are their distinctive tiger stripes down each side of their body. This pattern is clearest in juveniles and tends to fade with age, providing camouflage which enables juveniles to remain hidden from predators and hides adults from prey prior to attack. In addition to the stripes on their sides, they exhibit countershading like many other sharks, with a white underside to blend in with sunlit waters above and a darker dorsal surface to hide them when below their prey.
The tiger shark is the largest of the Requiem shark family (Carcharhinidae), which contains other notorious predatory sharks such as the Bull Shark (C.leucas) and Oceanic Whitetip (C. longimanus). Behind the white shark, they are the second largest predatory shark species, and the 4th largest shark species overall. Adult tiger sharks are typically between 3-4.5m in length, with a very broad head and large mouth. They have relatively large eyes, and their wide body shape means they can look relatively sluggish when swimming, however, they can swim in strong fast bursts when attempting to ambush prey.
Tiger sharks are solitary hunters, often feeding at night, and they are well known for feeding on a wide spectrum of prey species. They will eat most marine organisms, as well as seabirds and terrestrial carrion. They have even been recorded with a wide range of inedible manmade objects in their stomachs, from licence plates and car tyres to bottles and cans! This variety in prey species means that tiger sharks are especially important apex predators for maintaining balanced marine ecosystems and ensuring no prey populations grow to the point that they have negative impacts on other species. Similarly, their presence in and around seagrass beds is thought to protect these habitats from being overgrazed by turtles and other prey species. Though they are typically generalist feeders, in some areas around the world researchers have discovered individuals that have developed specialised feeding strategies, for example, feeding almost exclusively on seabirds or seals.
Despite being a predominantly coastal species, tagged tiger sharks have been recorded inhabiting depths from the surface to 1000m. They are also capable of undertaking seasonal migrations between the tropics and more temperate waters and can travel long distances across the ocean in relatively short time periods. Recent research suggests that in the Red Sea, tiger sharks may move into cooler waters in the north in summer, and then back towards the southern end of the Red Sea in the winter.
Compared to teleost (bony) fishes, like other sharks, tiger sharks are relatively slow growing, late to mature and have an estimated lifespan of 20-37 years. They reproduce by internal fertilisation and are ovoviviparous, which means they give birth to live young, but embryos develop inside eggcases within the mother's womb. Embryos receive nutrients from a yolk sac and hatch out of these eggcases prior to birth. Females can give birth to as many as 82 pups per litter, with an average litter size of between 30 and 35 pups.
As adult tiger sharks exhibit cannibalistic behaviours, juveniles are usually found in more protected areas such as estuaries and bays, whereas adults typically prefer more open ocean, energetic environments such as coral reefs. This division of habitat not only protects juvenile tiger sharks from other large predators, but also from being eaten by adult tiger sharks.
Tiger sharks are listed by the IUCN as Near Threatened, which means currently they are at lower risk of extinction than many other sharks found in the Red Sea, including the oceanic whitetip (C. longimanus), however, they are still threatened by fisheries around the world targeting them for their fins, meat and squalene oil.
Fortunately, in the Red Sea waters, all sharks are protected from fishing under local laws, national and regional agreements and conventions! The sale of sharks is also illegal. Protection of Tiger Sharks is particularly important given their role in managing populations of many prey species and protecting crucial habitats.
Author:
Marine Biologist | Trainer
RED SEA PROJECT™