Whale shark : The largest fish on the planet

According to the scientists and researchers, 95% portion of the oceans are still undiscovered and unexplored. We have no idea how many different types of species would be their inside the depths of the ocean. Speaking of the unknown depths of the sea, most of us think about the size of the creatures that can be found in there. Therefore today we are going to talk about one of those big creatures that can be found in the oceans but unlike the other unknown creatures, this one is actually known and studied. We are going to be talk about a creature which is referred as the largest and biggest fish on the planet which is the which is not "Blue whale"(in case your thinking). We are going to learn about the "Whale shark". So let's go.

Rhincodon typus (Whale shark)

General Info

Whale sharks are typical aquatic craniates/animals (fish) that are just big in size. They are the biggest specie among all the other types of sharks. These shark called whale sharks simply because, first of all they are sharks and second of all their size exceeds most of the sizes of  other sharks and are more similar to some whales (Like the Baleen whales). Whale sharks are free swimmers and are mainly found in almost all tropical oceans around the world. Every spring, they migrate to the central west cost region of Australia at the Ningaloo coast (Ningaloo reef). Their lifespan is estimated to be between 80 to 130 years although the average is above 100 years.

They are currently on the spot of "Endangered Species" on the IUCN red list. Their present population is around 7,000 in total.

Whale shark were first noticed and studied in April 1828 in Table bay, South Africa by a Scottish zoologist Sir Andrew Smith.

Whale sharks normally prefer slightly warm water and are rarely found in the water having less than 20 to 21 degree Celsius (68 to 69.8 degree Fahrenheit) in temperature. They use filter feeding to as their feeding method which only two other shark species use, that is, the Megamouth Shark and the basking shark. 

Physical Characteristics

Whale sharks have massive body size with a big, wide and flat head with two small eyes in front of it's head. They have 5 pair of gills in total with spiracles (openings used for respiration) on the side of their eyes. They have 20 filter pads and 300 rows of teeth inside their mouth. Their body color is grey (dark) or grayish-brown along with white spots on it and a white belly underneath. They have a quite heavy and thick skin with a thickness of nearly 6 inches (15 cm).

As for the dimensions, their average length is between 18 to 32 feet (~ 5.5 to 10 meters) and with a weight between 19,000 to 20,000 depending upon the gender. Although the largest specimen ever recorded was 61.68 feet (18.8 meter) in length and weighs around 50,000 pounds (~ 22,680 Kg).

Behavior, diet and lifestyle

Despite of their large size all well being a shark, they are not that deadly and does not posses any danger to humans. In fact many of the scuba divers and explorers are found to be taking photos and rides on the whale sharks. Although accidents can happen, like taking a hit from a whale sharks tail, but it is rare mostly. The younger whale sharks are slightly more playful as compared ti their adult counterparts. As mentioned, they prefer living in warm water in the tropical oceans and often migrate for feeding or breeding purpose.

    

These creatures spend most of their time near the surface of water and live and travel alone most of the time. But sometimes they are found travel in a depth up to 6,000 feet (1828.8 meters) inside the oceans. They are rarely with other whale sharks or in a small group during the migration or breeding season.

As for their diet and food consumption, they mainly feed on Plankton and other small aquatic creatures like crabs, tunas, squids, jellyfish, krills, sardines and floating fish eggs and larvae. The young whale sharks eats nearly 46 to 50 pounds per day (20.86 to 22.68 Kg). While the exact measure of the adults are unknown, it is estimated that the adult can eat nearly 1.5 or 2 times the food as compared to the young whale sharks.

Biological features

Filter feeding 

Whale sharks uses filter feeding method to eat the food. In this method, a large amount of water is sucked by the whale shark along with food. The 20 filter pads inside the mouth helps in trapping or catching the food whereas the 5 pair of gills in each side of their head is used to flush out the all the water. To be specific, they uses cross- flow filtration, in which the food flows in parallel to the filter pads inside the mouth. When the extra water is getting flushed out through the gills, the denser gets caught on the filter pads. For food present in low density area of water or which is suspended in water, they use passive feeding method in which they swim directly towards the target and open their mouth wide to get all the food covered it that cross section area. After that they simply use cross-flow filtration to get the food on their filter pads.

Coughing and propulsion

Whale sharks are often observed coughing in order to get the food from the filter pads directly to their stomach. They use a forward propulsion or generate a water pressure inside their mouth to remove the trapped food on their teeth or filter pads. Doing this will get the food easily to their stomach and prevents the fouling and decaying of the filter pads.

Reproduction

After reaching the age of sexual maturity which after 30 years, whale sharks start their migrating to find their breeding partner. Around 400 males show up near tropical islands ( like Isla Mujeres) to mate with females. Among these, most of the whale sharks are not sexually matured. The breeding season can last from the months of June to September. The gestation period of whale sharks is unknown.

Whale sharks are ovoviviparous, it means despite of the production of eggs, they give birth to young ones. The young whale sharks are hatched inside the body and egg shells are remained behind. The female can give birth to 300 "pups" (whale shark babies). Instead of giving birth to all the babies at once, the female actually gives birth in a steady rate overtime. Whale shark babies are of 1.31 to 1.96 feet (0.4 to 0.6 meters) in length and can weigh up to 6,000 pounds at the time of birth.

Facts and summary

• Whales are the biggest known specie of fish on the planet.

• They prefer living in warm water and near the surface.

• They are biggest among all the sharks.

• And if in case you need a visual comparison of their size with something they are big as school bus and some even slightly bigger than it.

• Whale sharks are ovoviviparous, it means despite of the production of eggs, they give birth to young ones. The young whale sharks are hatched inside the body and egg shells are remained behind.

• Babies of whale shark are called "pups".

• They are friendly in nature and are not deadly as most of the shark species.

• Also they get their food with filter feeding method unlike other sharks which are mostly ferocious predators.

• They can outtake and process around 6,000 litres of water through their gills.

• Their average life span is between 75 to 90 years and can even live up to 130 years.

• They are slow swimmers and cannot exceed a speed more than 3.1 miles per hour (5 Kmph).

• Young Whale sharks grow fast.

• They have a very thick skin, about 15 cm (6 inches).

• Although being shark and having a size of nearly a whale, they neither look like shark nor like a whale, instead they look like a giant cat fish.

• They have never eaten a human.

• Whale sharks have sensitive bellies.

• Whale sharks are sharks, not whales and whales are mammals, not fishes.

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Related : Blue Whales (Get to know about the largest animals on planet Earth)