Whale shark

Taxonomy:

Phylum– Chordata

Class– Chondrichthyles

Subclass– Elasmobranchii

Order– Orectolobiformes

Family– Rhincodontidae

Genus– Rhincodon

Species– typus

Status: IUCN Red List ENDANGERED

Average Size and Length: Typically, 33-36 feet, rarely over 40 feet in length. Max recorded length 65 feet.

Average Weight: 10 or more Tons. Usually doesn’t exceed 22 tons.

Teeth and Jaw: A whale shark has rows of over 300 rows of tiny teeth, but as filter feeders they do not use these teeth to eat.

Head: Whale sharks have flattened heads and have a blunt snout their mouth is over 5 feet wide. They have short barbells, or whisker-like sensory organs like catfish have that protrude from their nostrils.

Dermal Denticles: Each Whale shark dermal denticle has an extremely strong central keel, no lateral keels, and a tri-lobed rear margin. It would appear that the denticles are hydrodynamically important in its pelagic lifestyle.

Tail: Keel on the caudal peduncle and a lunate unnotched tail fin.

Demographic, Distribution, Habitat, Environment and Range: The Whale shark is found mainly in the open ocean but will congregate to feed near coasts and around reefs, estuaries and lagoons, as we see several times a year here in Jupiter, Florida. They are worldwide in tropical to warm oceans that range from 68-86 degrees F (20-30 degrees C). Whale sharks can be found at the surface down to 2,300 feet. The Red Sea is a popular area for juvenile whale sharks to hang out together and feed. 

Mating season and location of Whale sharks is still unknown, but according to the Galapagos Conservation Trust, preliminary findings from the Galapagos Whale Shark Project suggest that as high as 98% of individuals that pass through the marine reserve are female, the vast majority of which are not only mature but appear pregnant. This observation is truly unique among the known whale shark populations worldwide and could indicate that their birthing grounds are relatively close by. Some believe that the deep depths of the Darwin Islands are the key to the mysterious Whale shark nurseries. 

Diet: Whale sharks are meat-loving carnivores, but they are filter feeders. Plankton are their main food source, but they also eat shrimp, algae and other marine plant material, sardines, anchovies, mackerels, squid, tuna and albacore. A Whale shark delicacy is fish eggs. According to The Nature Conservatory, whale sharks will wait as long as 14 hours for fish to spawn on reefs. Then, they will swoop in and eat the eggs.

Ram-Suction Index: Whale sharks use three feeding methods:

Passive-swimming slowly with mouth open, straining plankton from the water.

Vertical-floating vertically, with little to no forward movement, using a suction method to draw prey into their mouths.

Active-suction filter-feeding while swimming steadily, enabling the whale sharks to draw water into their mouths at higher velocities. This type of feeding is also called “ram-filter feeding”.

They open their mouths, let water come in and their bodies filter out food, and release the water and any debris back into the ocean.

Aesthetic Identification: The markings on a Whale shark are extremely distinctive, and unforgettable. Whale sharks have greenish, bluish or greyish coloring on the back and sides, which pale to white on the lower flanks and underside. They have an intricate pattern of white, cream, pale, yellow, or grey spots and stripes like a checkerboard all along their backs, from head to tail. One of the most striking and beautiful patterns to see in the shark world. These spots and patterns are completely unique to each Whale shark, like human fingerprints.

Biology and Reproduction: The Whale shark is the largest shark and the largest fish in the ocean.

Researchers are still learning a lot about Whale sharks. It is unknown when Whale sharks reach sexual maturity, but it is thought around 30 years or 26-30 feet. Whale sharks are ovoviviparous, but the gestation period is still unknown. The size of a Whale shark’s litter is unclear, but one was recorded to have more than 300 developing pups still inside of her. 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” Pups are between 20-60 inches.

The lifespan of a Whale shark is still unknown, but research is suggesting more than 60 years and others more than 100 years.

Behavioral Traits, Sensing and Intelligence: Whale Sharks do endure long distances of migration. One whale shark’s 5,000-mile journey was documented.

Whale sharks are solitary creatures. They don’t shy away from sharing feeding grounds with other whale sharks, though.

Whale sharks have like a mirror behind the retina that helps them see in the dark. Their eyes are so small (about the size of a golf ball) that scientists are unsure how much whale sharks rely on their sense of sight. This also suggests that they have a wide field of vision. Unlike some other shark species, whale sharks lack eyelids.

Whale sharks have a strong sense of smell. They also have short barbells, or whisker-like sensory organs like catfish have that protrude from their nostrils. They use these to sense food, as well as their Ampullae of lorenzini.

Speed: Whale sharks are slow-moving, they typically do not exceed 3.5 mph.

Whale Shark Future and Conservation: More than 10 Whale Sharks are in captivity (Osaka, Okinawa Japan and Atlanta, Georgia, USA).

Whale shark fins are sold in the Orient, especially in the Hong Kong.

Whale Shark Recorded Attacks on Humans: None. Not a threat to humans.