by Amica Limosani, Jake New, Barbara Wueringer
The Carcharhinidae family, also known as whaler sharks, includes 12 genera and 50 species worldwide, making it one of the largest families of sharks. These sharks are typically found in warm tropical waters, although some species can also be found in brackish and freshwater environments, therefore we encounter these often in the field. Carcharhinids are highly recognizable, often having the classic shark-like shape that many people associate with these animals.
Speartooth Shark, Glyphis glyphis
Imagine a shark with spear-like teeth navigating freshwater rivers! Meet the Speartooth Shark, Glyphis glyphis, found in selected tropical rivers and estuaries in northern Australia and New Guinea. They are one of the few shark species adapted to freshwater habitats. These elusive sharks are hard to study due to their cryptic nature and remote homes. Sadly, they are critically endangered because of habitat degradation, pollution, and accidental capture in fishing gear. Conservation efforts are crucial to ensure their survival.
Sicklefin Lemon Shark, Negaprion acudentis
Introducing the striking Sicklefin Lemon Shark (Negaprion acutidens)! While most shark enthusiasts are familiar with the Atlantic lemon shark (N. breviostris), widely researched by the Bimini Biological Field Station, the Sicklefin Lemon Shark is equally fascinating. They are easily recognizable by their slender, curved fins, particularly their two equal-sized distinctive sickle-shaped dorsal fins. They often inhabit shallow coastal waters, including mangroves and coral reefs, but are also known to explore farther offshore. With a nocturnal hunting habit, they prey on fish, crustaceans, and cephalopods. Renowned for their relatively docile nature compared to other shark species, encountering them is an unforgettable experience.
Pigeye shark, Carcharhinus amboinensis
Pigeye sharks are sporadically spread throughout the tropical waters of the Indo-West Pacific. They inhabit brackish coastal water and tend to swim close to the ocean floor. Pigeye sharks often get confused with Bull sharks because it is so hard to distinguish the two. Due to this misidentification, there is little information on the Pigeye sharks. According to the IUCN Red List, pigeye sharks in Australia are classified as least concern, though their population sizes have never been recorded. However, they often end up as bycatch in gillnets and longline fisheries. Currently, they are not targeted by fisheries and are considered sustainable. However, they are caught in gillnets and longline fisheries as bycatch.
Coates or Australian blackspot shark, Carcharhinus coatesi
Have you ever heard of a Coates or Australian Blackspot Shark, (Carcharhinus coatesi)? Despite recent reclassification and its elusive nature, this species remains largely unstudied. Females give birth to small litters of 1-3 pups, each measuring between 38-40 cm at birth, with adults reaching lengths of up to 88-92 cm.
This species is differentiated from the spot-tail shark as it does not have black markings on the lower caudal fin.
Creek Whaler, Carcharhinus fitzroyensis
Say hello to the intriguing Carcharhinus fitzroyensis (Creek Whaler)! Endemic to the tropical waters of Northern Australia, this small shark species holds many secrets waiting to be discovered. With a maximum length of 135 cm, most individuals measure between 80-90 cm. Sporting a spindle-shaped, stocky body, five gill slits, and a long snout, this shark is a remarkable inhabitant of our oceans.
It is easily identified as it lacks any black fin markings.
Nervous Shark, Carcharhinus cautus
Have you ever seen a nervous shark, Carcharhinus cautus? Aptly named for its skittish behavior, this shark often darts away when approached by divers or boats, keeping its distance from potential threats. Found in tropical and subtropical waters, primarily in the Indo-Pacific region, they navigate their habitat with caution. Sporting a streamlined body, pointed snout, and large eyes, these features likely contribute to their cautious nature.
Do not confuse the nervous shark with a lemon shark, even though it is slightly greenish in body colour, its dorsal fins are not equal in height.
Bull Shark, Carcharhinus leucas
With the unique ability to thrive in both saltwater and freshwater, these sharks are true survivors. They navigate rivers and estuaries, sometimes venturing hundreds of miles upstream in search of prey and new territories. Known for their aggressive behavior, they’re often regarded as one of the most formidable shark species to encounter in the wild. Despite coastal environments being heavily impacted by human development, Bull Sharks have adapted and expanded their habitat in Australia to the Gold Coast canals (J. Werry, 2016)!
Blacktip Shark, Carcharhinus limbatus
Introducing the Blacktip Shark, Carcharhinus limbatus! These sharks have black markings on their fins which are not as pronounced as those of blacktip reef Carcharhinus melanopterus. Beware to not confuse the two! Blacktip sharks are common in tropical and subtropical coastal waters worldwide, and they can grow up to 250 cm TL but average around 150cm. They are frequently found nearshore around river mouths, bays, mangrove swamps, and estuaries, though they do not venture far into freshwater. Fun fact their ‘black tips’ fade over time (Compagno et al. 2005). Blacktip sharks are listed as Vulnerable globally (IUCN, 2020) and are targeted by multiple commercial fisheries around the world.
Australian Blacktip Shark, Carcharhinus tilstoni
Meet the Australian blacktip shark, Carcharhinus tilstoni! Named for their black-tipped dorsal and pectoral fins, these sharks are only found in shallow coastal waters across northern Australia, often swimming in schools near coral reefs and estuaries. With streamlined bodies and large eyes, they have excellent vision for hunting. Primarily fish-eaters, they feed on small fish and cephalopods, playing a crucial role in marine ecosystems. Previously the Australian Blacktip and the global Blacktip shark Carcharhinus limbatus could only be distinguished by genetic analysis. However, scientists from NT Fisheries have found that the markings of the anal fins of both species are different, making it possible to differentiate the two in the field!
Graceful Shark, Carcharhinus amblyrhynchoides
Named for their smooth swimming style and sleek, streamlined bodies, these sharks are a marvel to watch. With their slender bodies, rounded snouts, and large eyes, graceful sharks have excellent vision in low-light conditions, making them effective nocturnal hunters. Interestingly, graceful sharks are often mistaken for bull sharks because they both have a stocky build. Can you spot the difference?