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Blue whales are the largest animals to have ever lived on our planet. Being endangered animals, it’s important that children learn about their behaviour, habitat, population and the influence of human activity have on them.
What is a Blue Whale?
Blue whales (scientific name Balaenoptera Musculus) are the largest animals on the planet; they can grow to lengths of around 30m (100ft) and weigh over 150 tons. Although these marine animals resemble fishes in their physical appearance, they have more in common with us than they have with fish; they are mammals. They give birth to live young ones and suckle them for 6-9 months till they grow. Blue whales are found in all of the world’s oceans and mostly spend summers close to the arctic waters feeding on krill. They are relatively solitary animals and are often found alone or in pairs of two adults or mother and calf, and even then, they are known to swim several kilometres apart. Although they are aquatic animals, blue whales cannot breathe underwater. They have to surface periodically for breaths of air. They are known to stay submerged for periods up to 20 minutes when feeding and dive up to a depth of 500 meters.
Physical Features of Blue Whale
- Blue whales aren’t as blue as they seem in deep waters, it’s an effect caused by sunlight and the depth of the ocean around. In reality, they are greyish blue.
- A fully mature whale can grow up to 30 meters long, and their average length is around 20 to 25 meters. The longest recorded whale measured 33.5m.
- Their flippers measure 3-4 meters in width which is only about 12% of its overall length. They also have small triangular dorsal fins to help them steer in the water.
- Being the largest animals, they also are super-heavy. Their weight can range from 150 to 190 tons (150000 -190000Kg) which is about the weight of 30 adult elephants.
- Despite their enormous size, they are graceful swimmers thanks to their streamlined body which almost gives them the appearance of a submarine from the air. They swim at an average speed of 20 Km/hr and can reach a top speed of 50 km/hr.
Blue Whale Diet
- Blue whales are carnivorous, and their diet consists of some of the smallest animals in the ocean called Krill.
- Krill are small crustaceans that are similar to shrimp and measure in size between 1-5 cm on an average. A few species can also grow to sizes of 10-12cm.
- Krill are often found in the ocean travelling in dense masses that are referred to as swarms or clouds. Their body is often pinkish-red in colour, and when they travel in a large enough mass, they make the ocean look pink from above.
- Blue whales are also called Baleen whales due to the way their mouth has evolved to feed on Krill. Unlike other whales that have teeth, blue whales have baleen plates to eat the small crustaceans in a method called filter feeding.
- The whale swims into a swarm of krill with its mouth wide open to collect as much krill as it can. Then they shut their mouth and expel the water out using their tongue while the baleen bristles act like a filter to trap their prey.
- They feed about 4000-6000 kg of krill a day, which is over 40 million of the little crustaceans.
Blue Whale Habitat
- They live in all the oceans around the globe and depending on the time of the year; they can be found in different oceans.
- Most of the year they can be found in the Arctic and Antarctic water where they follow the Krill masses. During mating season they migrate to warmer tropical waters to mate and give birth.
- One interesting fact about blue whale habitat for kids is that one of the largest colonies of blue whales was recently found close to Sri Lanka. It remained undiscovered due to three decades of conflict in the region that had made it off limits to most locals and researchers.
How do Blue Whales Give Birth?
- They reach sexual maturity at the ages of 5-10 years, while their total lifespan is about 80 years. Their mating season lies between autumn to the end of winter.
- Their gestation period is between 10-12 months at the end of which the female gives birth to a single calf.
- At birth the calf measures 6 to 7.5 meters in length which are about 1/4th – 1/3rd the size of an adult whale and weigh about 2500kg.
- The mothers feed the newborn babies for the first 6-9 months through a nipple. A newly born calf can drink up to 400 litres of milk a day and continues drinking until about 7-9 months. The milk is rich in fat and all the vital nutrients that will help it develop.
- Once the mother stops nursing the calf, it will begin to feed on solid food and hunt on its own.
- As with other baleen whales, once they reach adulthood, the females tend to be larger than the males.
Are Blue Whales Endangered?
- Blue whales are considered as an endangered species due to their low numbers left in the oceans.
- Before the whaling era estimated 200,000-300,000 blue whales existed in the world’s oceans. Uncontrolled hunting by humans caused their numbers to plummet to 5000-12000.
- During the industrial age, Blue whales were hunted for their blubber (to extract oil), food, clothing and other products made out of whale body parts. The improving technology in hunting and shipbuilding made it easier to catch whales.
- After 1931 international agreements were made to regulate whaling in an effort to let populations of whales to recover from the brink of extinction.
- It has also been observed that whales could communicate up to 1,600km underwater using sounds prior to the 1940’s. Since then a steady rise of cargo freights and ships in the ocean has increased noise pollution limiting their communication distances to the only 160km. This has significantly impacted their mating behaviour leading to lowers numbers.
Other Interesting Facts about Blue Whales for Children
Here are some blue whale fun facts for kids that are easy to remember:
- The blue whale blows, also called spouts at the time of their exhalation consists of air and water. They can shoot up to 9 (30ft) meters into the air.
- Their lungs can hold 5000 litres of air during dives.
- Blue whales are not only the largest animals now, but they are also the largest animals to have ever existed on the planet. They are larger than even the dinosaurs were.
- Other than humans, the only natural predator’s blue whales have are a pack of hungry killer whales. However, killer whales mostly target the calves, and their hunt is rarely successful.
- They are also considered as apex predators of the oceans as they can travel through the oceans hunting without worrying about being hunted themselves.
- When hunting, blue whales can dive to depths of 500 meters and hold their breath for 35 minutes.
- It is estimated that over about 95%-99% of the blue whale population was wiped out during the whaling era.
- Blue whales are the loudest animals on the planet with their volume greater than 180 decibels. In comparison, the sound of a jet engine at full thrust is 130 decibels.
- They also have exceptionally deep voices at frequencies around 14Hz which is inaudible to us.
- Blue whales have mating songs to communicate. They are also known to have dialects which depend on which ocean they are in.
- They also sleep while swimming and only half of their brain are awake.
- Their mouth is large enough to fit 100 people, and yet their food pipe is so small that a human cannot pass through.
- Their tongue alone weighs as much as an elephant.
- They normally swim around 10km/hr but can go up to 50 km/hr when threatened.
- Blue whales are related to hippopotamus through their genetic ancestry.
Although everything about blue whales is massive, they are gentle creatures of the ocean.
Also Read: Amazing Animal Facts for Kids