About Whale Sharks
As the largest fish in the sea, reaching lengths of 40 feet or more, whale sharks have an enormous menu from which to choose. Fortunately for most sea-dwellers—and us!—their favorite meal is plankton. They scoop these tiny plants and animals up, along with any small fish that happen to be around, with their colossal gaping mouths while swimming close to the water's surface.
Characteristics
Preferring warm waters, whale sharks populate all tropical seas. They are known to migrate every spring to the continental shelf of the central west coast of Australia. The coral spawning of the area's Ningaloo Reef provides the whale shark with an abundant supply of plankton.
Although massive, whale sharks are docile fish and sometimes allow swimmers to hitch a ride.
The whale shark's flattened head sports a blunt snout above its mouth with short barbels protruding from its nostrils. Its back and sides are gray to brown with white spots among pale vertical and horizontal stripes, and its belly is white. Its two dorsal fins are set rearward on its body, which ends in a large dual-lobbed caudal fin (or tail).
Habitat
The whale shark, like the world's second largest fish, the basking shark, is a filter feeder. In order to eat, the beast juts out its formidably sized jaws and passively filters everything in its path. The mechanism is theorized to be a technique called “cross-flow filtration,” similar to some bony fish and baleen whales.
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Whale sharks feed on wide variety of planktonic (microscopic) and nektonic (larger free-swimming) prey, such as small crustaceans, schooling fishes, and occasionally on tuna and squids. Also, phytoplankton (microscopic plants) and macroalgae (larger plants) may form a component of the diet.
Whale sharks are ovoviviparous. The eggs remain in the body and the females give birth to live young which are 40 to 60 cm (16 to 24 in) long. This is known from a single pregnant female that was caught in 1995 off the coast of Taiwan. Inside the uterus of this female, which was nicknamed “megamamma supreme”, scientists found over 300 embryos, far exceeding the highest number found in any other shark. Interestingly, many of these embryos were at different stages of development – some were still in their egg cases whilst others had emerged but were still in the uterus. This may signify that females are able to store a male’s sperm, selectively fertilising her eggs over a prolonged period.
Reproduction
Diet
Whale sharks are highly valued on international markets. Demand for their meat, fins and oil remains a threat to the species, particularly by unregulated fisheries. They are victims of bycatch, the accidental capture of non-target species in fishing gear. And whale shark tourism presents a threat to the species as it can interrupt their feeding and sharks can be injured by boat propellers. They are currently listed as a vulnerable species; however, they continue to be hunted in parts of Asia, such as the Philippines.
Threats
COMMON NAME
Whale Shark
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SCIENTIFIC NAME
Rhincodon typus
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STATUS
Vulnerable
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TYPE
Fish
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DIET
Carnivores
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GROUP NAME
School
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AVERAGE LIFE SPAN IN THE WILD
70 years
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SIZE
18 to 32.8 ft
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WEIGHT
20.6 tons
Info gathered from National Geographic, Florida Museum, Lonely Planet, World Wildlife Fund, Smithsonian, and Live-science
