Requiem Sharks are a family of sharks of the order Carcharhiniformes, which is the largest order of sharks containing 260 unique species. There is some confusion behind the origin of their name. Some scientists attribute it to the French word for “rest (death)” which may refer to their impressive hunting skills, while others believe it is from the term “reschignier” which means “to grimace while bearing teeth.” Requiem Sharks are found all over the world and are one of the most studied and fascinating types of sharks.
What Are Some Species Of Requiem Shark?
Species of Requiem Sharks vary in size from the smallest, the Australian Sharpnose Shark at 2.26 ft (69 cm) to the largest the Tiger Shark at 18 ft (5.5 m). Though most Requiem Sharks all share very common features, the family includes 60 unique types of sharks. The most commonly known Requiem Sharks include:
- Tiger Sharks
- White Tip Reef Sharks
- Lemon Sharks
- Blue Sharks
- Daggernose Sharks
- Sharpnose Sharks
- Sliteye Sharks
- Milk Sharks
- River Sharks
- Dusky Sharks
Where Do Requiem Sharks Live?
Requiem Sharks are found in oceans all over the world. They are highly migratory, and hunt their prey along great distances, but they prefer warm tropical waters. Though sometimes their migratory hunting takes them into temperate zones during the late Spring, Summer, and early Autumn. They are typically found in barrier reefs, along coasts, and in estuaries. Requiem Sharks include the rare species of river sharks the Borneo River Shark, Ganges Shark, and Northern River Shark, which are found in brackish and freshwater habitats. Bull Sharks are also known to swim upriver into freshwater for food. The are often bottom dwelling species and tend to stick to shallower waters, except when migrating.
What Does Requiem Sharks Look Like?
Requiem sharks all have round eyes with nictating membranes. They also have five gill slits along the sides of their heads. Behind their gills, they have large pectoral fins. Their bodies are long, slender and tapered, and they have rounded snouts with no spiracles (except on Tiger Sharks). Their snouts are filled with sharp, blade-like teen with a single cusp. They tend to be grey or brown in color with a white belly, a type of camouflage known as countershading. Since most requiem sharks share the same physical characteristics and overlapping habitats, they are incredibly hard to tell apart from one another. So even though they are extremely well studied, it can be difficult to successfully track the behaviors of each unique subspecies of Requiem Shark. Most often, different species are identified by the patterning on their pectoral fins.
How Do Requiem Sharks Hunt?
Requiem Sharks are incredibly fast and effective hunters. Their elongated, torpedo-shaped bodies make them quick and agile swimmers, so they can easily attack any prey. They have a range of food sources depending on their location and species that includes bony fish, squids, octopuses, lobsters, turtles, marine mammals, seabirds, other sharks, and rays. Requiem Sharks are often considered the “garbage cans” of the sea because they will eat almost anything, even non-food items like trash. They are migratory hunters that follow their food sources across entire oceans. They tend to be most active at night time, where their impressive eyesight can help them sneak up on unsuspecting prey. Most Requiem Sharks hunt alone, however some species like the White Tip Reef Sharks and Lemon Sharks are cooperative feeders and will hunt in packs through coordinated, timed attacks against their prey. This behavior is often called a “feeding frenzy” though this term is a misnomer because it is a very directed, deliberate behavior and not just a mindless killing spree.
How Do Requiem Sharks Mate?
Most Requiem Sharks travel great distances to mate. Depending on the species, their mating season varies from late Spring to early Autumn. Typically when it is mating season the females will release chemicals into the water signaling the males they are ready for copulation. The males respond by biting the female sharks until one accepts the advances. When copulation begins the male inserts their reproductive organ a clasper into the female’s cloaca, where the embryos are fertilized. Requiem Sharks are viviparous which means they give live birth to their pups. Their pups are usually born in the brackish waters of river mouths and estuaries, where food is plentiful and the dark waters help camouflage them, giving them a greater chance at life.
Human Interactions With Requiem Sharks
Over half of all shark attacks are attributed to Requiem Sharks. Though since the different species tend to resemble each other, these reports are not completely accurate. Requiem Sharks are typically aggressive hunters with a varied diet, so often times they will attack if provoked or even just curious about humans as a food source. They also tend to live along coastal shores where humans tend to swim. So the frequency of attacks is not necessarily because of the nature of Requiem Sharks, but more because of the circumstances of human interactions. In fact, an estimated 60% of all Requiem Shark attacks are the product of provoked attacks. Especially since Requiem Shark meat is highly valued for its flavor all over the world. Most Requiem Shark attacks happen as a product of commercial fishing or because a spear hunter was prodding the shark, and not because these sharks were specifically hunting humans. So even though they account for a high percentage of shark attacks, they are not really a threat to humans.
Requiem Sharks are generally a well known species of shark. Since they are often found swimming in the same warm, coastal waters as humans, they are easy track and observe. They are incredible migratory hunters, fast swimmers, and have a very diverse diet. However, because so many share very similar characteristics, they are hard to tell apart which can often lead to confusion about their unique behaviors. Requiem Sharks are just one of the many 440 wonderful species of sharks roaming our oceans, but since we often interact with them more than other types of sharks, it’s great to get to know them.
I am broadly interested in how human activities influence the ability of wildlife to persist in the modified environments that we create.
Specifically, my research investigates how the configuration and composition of landscapes influence the movement and population dynamics of forest birds. Both natural and human-derived fragmenting of habitat can influence where birds settle, how they access the resources they need to survive and reproduce, and these factors in turn affect population demographics. Most recently, I have been studying the ability of individuals to move through and utilize forested areas which have been modified through timber harvest as they seek out resources for the breeding and postfledging phases. As well I am working in collaboration with Parks Canada scientists to examine in the influence of high density moose populations on forest bird communities in Gros Morne National Park. Many of my projects are conducted in collaboration or consultation with representatives of industry and government agencies, seeking to improve the management and sustainability of natural resource extraction.