The whale shark (Rhincodon typus) is the largest living fish and non-cetacean animal on earth. Despite their sometimes confusing name, they are NOT whales, just the biggest shark! Large adults are usually between 10-12 meters in length but have been recorded at a maximum length of around 18 meters . It is estimated that they have a lifespan of between 80-130 years.
They have a very large mouth at the front of their wide, flat head (unlike many other sharks, which have mouths on the undersides of their heads). They have a rounded snout and small eyes with spiracles (used in respiration) located just behind the eyes. Their fins include: 2 dorsal fins (on the back), 2 pectoral fins (on its sides), 2 pelvic fins, a single anal fin and a caudal (tail) fin with a much larger upper lobe than lower lobe.
Whale sharks have a distinctive white-to-light grey, spotted and striped pattern on dark grey skin, so as well as being huge, they are easily identifiable. This spot patterning is unique to each individual, just like human fingerprints, so their spots are often used in Photo Identification studies.
Recent research has revealed a lot of new information about this species. For example, a 2020 study discovered that they have dermal denticles, which are usually found across the skin of shark species, on the surface of their eyeballs in order to protect their eyes from damage. Additionally, they are able to retract the eyeball back into their eye socket to protect it from damage.
Despite their enormous size, whale sharks are filter feeders, they have small teeth but do not bite or chew their food. Their feeding method involves the suction of seawater whilst swimming, then sieving and filtering small fish, squid, krill and shrimp, and other planktonic organisms through their gill rakers. These gill rakers are bristly structures in the shark's mouth (consisting of thousands of bristles which are about 10 cm long, that trap the small organisms which the shark then swallows. Water is then expelled through 5 gill slits. It is estimated that their mouths can reach sizes of 1.5 meter across and when feeding, whale sharks can take in more than 6000 litres of water every hour. They often feed at the surface and can be seen by people on boats and snorkellers, but they are able to dive to depths greater than 1000 meters.
Whale sharks are found in tropical ocean regions worldwide, usually between latitudes 30°N and 35°S, and is thought to prefer sea surface temperatures between 21 to 25°C. They are highly migratory and are known to inhabit coastal waters and lagoons of coral atolls and reefs.
Whale sharks in the Red Sea:
Whale sharks are a seasonal visitor to the Red Sea and can be found most frequently in the upper Red Sea region between May and July. The whale shark is protected in Egyptian waters under State, Commonwealth and international legislation and it is illegal to disturb, touch, feed, harm or fish for whale sharks.
Studies have shown that within large aggregations of young whale sharks gathering in the southern Red Sea, many of the same individuals returned year on year. Interestingly, this research discovered that the group of young sharks consisted of a roughly equal number of males and females, whereas many other aggregation sites are dominated by males. Many individuals are known to remain in the area around where they were tagged, suggesting the southern Red Sea may be a critical habitat for this juvenile population.
To ensure that interacting with whale sharks is a safe, enjoyable experience and to prevent the animals themselves from being harmed or disturbed, the following Code of Conduct applies when interacting with whale sharks:
Keep noise to a minimum; Enter the water slowly from the boat- do not jump in.
Keep your fins underwater and avoid using your arms to reduce splash.
Look, but DON'T touch. If the whale shark is startled or chased they'll normally dive instantly which spoils the encounter for everyone else and stresses the shark.
Keep safe distance; Stay at least 3m away from the head and 4m away from the tail. if the whale shark comes directly towards the group, remain calm and split into two groups so that the shark can swim between you.
Do NOT chase the whale shark or block their path.
Do NOT conduct free diving or duck diving on the top of the shark.
Do NOT restrict their natural behavior and movement. Let the shark control the encounter
Avoid excessive flash photography. If necessary; avoid pointing the flash directly into their eyes, if you spot the pattern above the whale shark's pectoral fin (One or both sides) we can identify the shark. Support ongoing research by submitting your Sighting Report.
Report any type of chasing, illegal fishing or disturbance to the authorities.
The IUCN categorises whale sharks as endangered on the Red List with populations currently decreasing. Whilst little is known about natural threats to whale sharks, human activity is their biggest threat. Examples of this include: targeted fishing for their fins, meat and oil (though in many places this is banned), accidental removal as bycatch in other fisheries, significant injury from vessel strikes, entanglement and pollution. In Taiwan, whale sharks are known as ‘Tofu fish' because of the taste and texture of their flesh, and their fins can fetch up to US$15,000 on the black market for use in shark fin soup.
Sharing the water with the biggest fish in the sea is a feeling that is difficult to describe. While some people may be intimidated by its size, the whale shark really is a gentle giant keen to avoid confrontation and generally trusting of humans.
Authors:
RED SEA PROJECT™
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