Whale Shark

The whale shark (Rhincodon typus) is a large, slow-moving filter-feeding shark that holds the title for being the largest known fish species. Measuring up to 18.8 meters (61.7 feet) in length, the whale shark is the most massive living non-mammalian animal. It is the only extant member of the family Rhincodontidae and the sole member of the genus Rhincodon, belonging to the subclass Elasmobranchii in the class Chondrichthyes.

Whale sharks can be found in the open waters of tropical oceans, preferring temperatures above 21 °C (70 °F). Their lifespan is estimated to be between 80 and 130 years, determined by studying their vertebral growth bands and growth rates. These majestic creatures have large mouths and are filter feeders, sharing this feeding mode with only the megamouth shark and basking shark. Their diet primarily consists of plankton and small fish, presenting no danger to humans.

The species was identified in April 1828 after the harpooning of a 4.6-meter (15-foot) specimen in Table Bay, 🇿🇦 South Africa. Andrew Smith, a military doctor associated with British troops in Cape Town, described the shark the following year. Despite its name, the whale shark is a fish, not a mammal, and is unrelated to whales. Its filter feeding habits bear resemblance to those of baleen whales.

Whale sharks have a flattened head with a broad mouth situated at the front rather than underneath. The largest recorded whale shark had a mouth 1.55 meters (5.1 feet) across. With over 300 rows of tiny teeth and 20 filter pads, they employ these structures for filter feeding. The eyes of whale sharks are positioned just behind their eyes, which possess dermal denticles and can be retracted to protect them from damage. The shark's skin is dark grey with a white belly adorned with unique pale grey or white spots and stripes. The skin is thick, reaching up to 15 centimeters (5.9 inches) in thickness, and possesses a rough texture. Whale sharks possess three prominent ridges along their sides, with dorsal fins set far back on their body, as well as pectoral fins, pelvic fins, and a single medial anal fin.

Remarkably, whale sharks have the ability to regenerate small sections of their fins and reform spot markings over previously wounded areas. Their eyes contain a light-sensing pigment called rhodopsin, which enables them to see well in the deep ocean where blue light prevails. Furthermore, the whale shark's eyes have lost all cone opsins except LWS, allowing them to see at both ends of their vast vertical range.

Sexual dimorphism is observed in whale sharks, with females generally growing larger than males. Growth studies indicate that males typically reach lengths of 8 to 9 meters (26 to 30 feet) while females are predicted to average around 14.5 meters (48 feet). However, maximum sizes are uncertain due to a lack of detailed documentation. Sexual maturity occurs at approximately 8 to 9 meters (26 to 30 feet), although there is limited evidence for females possibly maturing at a similar or larger size. In-water measurements of whale sharks are challenging to obtain accurately, and estimates range from 14 to 21.9 meters (46 to 72 feet) in length.

Whale sharks can be found in tropical and warm-temperate seas, inhabiting both coastal and oceanic habitats. They display dynamic patterns of habitat utilization in response to prey availability. The species is migratory, with an Atlantic subpopulation from Maine to 🇿🇦 South Africa and an Indo-Pacific subpopulation that comprises 75% of the species. Seasonal feeding aggregations occur at various coastal sites worldwide.

Despite their size, whale sharks are gentle creatures that pose no danger to humans. They are known to interact peacefully with swimmers, although scientists and conservationists discourage this practice to avoid disturbance. These docile fish have been observed in many locations worldwide and are frequently sighted by divers. In certain regions, they hold cultural significance and are named accordingly, such as "marokintana" in 🇲🇬 Madagascar and "butanding" in the 🇵🇭 Philippines. The whale shark is featured on currency in several countries, including the 100-peso bill in the 🇵🇭 Philippines and the 1000 rufiyaa banknote in the 🇲🇻 Maldives.

Understanding the growth, longevity, and reproduction of whale sharks remains a challenge, and further research is needed. Their filter-feeding behavior sets them apart from other shark species, allowing them to consume plankton, fish eggs, small nektonic life, and clouds of spawning eggs. Whale sharks are a marvel of nature, exemplifying the beauty and diversity of marine life, while coexisting peacefully with humans.