Commonly Asked Questions Appears in Georgia Aquarium's:
Range / Habitat
- Whale shark occurs worldwide in the tropical Atlantic, Pacific, and Indian Oceans between about 30 degrees North and 35 degrees South. It has been sighted as far as 41 degrees North and 36.5 degrees South, and is very rarely found in the Mediterranean Sea.
- Typically found offshore but will come close inshore, sometimes entering lagoons or coral atolls. Frequents shallow water areas near estuaries and river mouths, sometimes during seasonal plankton blooms.
- Whale shark is the largest of all fishes. Because of its size and cartilaginous skeleton, it is very difficult to weigh accurately. Females are larger than males, as in most shark species.
- The largest accurately measured whale shark was 40 feet 7 inches (12.2 m), although there are anecdotal reports of a 60-foot (18 m) whale shark in 1925.
- The average length is between 18 and 32.8 feet (5.5 - 10 m).
- Newborns measure 21 to 25 inches (53 - 64 cm) long.
- Body Composition
- Whale shark has a broad, flat head, small eyes, five large gill slits, two dorsal fins, two long pectoral fins, and a large sweeping tail. It has a vestigial spiracle behind the eye, which may be evidence of evolution from bottom-dwelling carpet sharks.
- Unlike most shark species, its mouth is located at the front of the head instead of the underside of the rostrum.
- The whale shark has a huge mouth which can reach up to 4 feet (1.4 m) across located at the front of the head.
- The skin of a whale shark can be as thick as 4 inches (10 cm), which limits possible predators to killer whales, great white sharks, tiger sharks and humans.
- Whale shark has a two-toned pattern of light spots on its dark gray back with a white underside.
- A whale shark’s strong pattern and coloration may be evidence of its evolutionary relationship to benthic carpet sharks.
- Teeth of the whale shark are tiny and pointed backward; thought to have no function in feeding.
- There are about 300 rows of tiny teeth along the inner surface of each jaw, just inside the mouth.
Diet / Feeding
- Consists of zooplankton (krill, larvae, jellies, copepods, etc) and small fishes (sardines, anchovies, etc).
- Can only swallow small prey because its throat is very narrow, often compared to the size of a quarter.
- Feeding behaviors
- Whale shark uses multiple feeding methods:
- The first is considered passive feeding, where the shark swims with its mouth open, continually collecting food as it goes.
- When food concentrations are high, the shark will use one of two suction-type feeding methods:
- One where the shark hovers vertically, nearly motionless.
- Another where the shark swims normally.
- During these feedings, the shark will open and close its mouth, creating a strong suction, bringing in larger volumes of water.
- When the sharks are fed in Ocean Voyager, they employ this suction-type feeding style, while following feeding ladles along the surface.
- During horizontal feeding, part of its head may be lifted out of the water. It will open and close its mouth 7 to 28 times per minute with suction gulps synchronized with the opening and closing of the gill slits.
- Strains food through specialized “pads” that sit in front of their gills. The pads catch food particles as the water passes over them and out past the gills.
Reproduction / Growth
- The whale shark is ovoviviparous, meaning the embryo is formed within an egg retained in the mother’s uterus. At term, the young are released into the sea fully-formed. The litter size can be over 300 pups.
- Very little is known about whale shark mating behavior as it has never been observed in either its natural habitat or in an aquarium setting.
- “Vulnerable” on the IUCN Red List.
- Appendix II of CITES.
- World populations of whale sharks have decreased dramatically in recent years due to heavy fishing driven by market demand in Asia for whale shark meat and shark fins.
- Swim Speed
- Whale shark is slow-swimming and often seen feeding at the surface.
- Usual swim speed when feeding at the surface is roughly 2 knots (a typical walking pace at 2.3 mph). When cruising, it averages about 2.5 knots (2.9 mph). When alarmed, the whale shark has been observed accelerating to a body length per second for very short bursts.
- Known to be highly migratory, ranging thousands of miles. It will migrate between ocean basins and national jurisdictions, but will usually return to the same sites annually.
SourcesSharks & Rays. Hennemann, R. M.