My Science School

Blue whales are the largest animals ever to live on our planet. They feed almost exclusively on krill, straining huge volumes of ocean water through their baleen plates (which hang from the roof of the mouth and work like a sieve). Some of the biggest individuals may eat up to 6 tons of krill a day.

Blue whales are found in all oceans except the Arctic Ocean. There are five currently recognized subspecies of blue whales.

The number of blue whales today is only a small fraction of what it was before modern commercial whaling significantly reduced their numbers during the early 1900s, but populations are increasing globally. The primary threats blue whales currently face are vessel strikes and entanglements in fishing gear.

Blue whales sometimes swim in small groups but are more often found alone or in pairs. They generally spend summers feeding in polar waters and undertake lengthy migrations towards the equatorial waters as winter arrives.

Blue whales typically swim at about 5 miles an hour while they are feeding and traveling, but can accelerate to more than 20 miles an hour for short bursts. They are among the loudest animals on the planet, emitting a series of pulses, groans, and moans, and it is thought that in the right oceanographic conditions, sounds emitted by blue whales can be heard by other whales up to 1,000 miles away. Scientists think they use these vocalizations to communicate and—along with their excellent hearing—perhaps to sonar-navigate the dark ocean depths.

The primary diet of blue whales is krill—tiny shrimp-like animals, but fish and copepods (tiny crustaceans) may occasionally be part of the blue whale’s diet. When blue whales hunt for food, they filter feed by swimming toward large schools of krill with their mouth open and closing their mouths around the krill while inflating their throat pleats. Once closed, blue whales then push the trapped water out of their mouth with their tongue and use their baleen plates to keep the krill trapped inside.

Credit : NOAA Fisheries 

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Blue whales are the largest animals ever to have lived on Earth. They can grow to a length of 30 metres and weigh 173 tonnes. Also among the loudest animals on the planet, the blue whale can make a range of sounds to communicate with others of the species hundred miles away and to navigate.

Now, scientists have determined how much energy species of different sizes invest to capture their prey and which of these species reap the greatest rewards for their efforts. To do so, they gathered data from hundreds of feeding whales.

The results demonstrated that the availability of their prey limits that body size in all whales, but only filter-feeding whales have evolved a feeding strategy that helps them to achieve the largest body sizes to have ever evolved on Earth.

Scientists obtained the data for their study after seeking and tagging whales, porpoises, and dolphins of various sizes—from 5-foot-long harbor porpoises to gigantic blue whales. They also tracked animals’ underwater activities using multi-sensor tags, which were temporarily affixed on animals’ backs via suction cups, reaching from their boats with long poles to stick.

Credit :  Tech Explorist 

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The Goliath birdeater tarantula from South America is the largest spider in the world. Weighing up to 170 gm, its legs can reach up to one foot. Hunting at night, its diet mainly comprises earthworms, insects and frogs.

The Goliath bird-eating tarantula lives in the rainforest regions of northern South America, including Venezuela, northern Brazil, Guyana, French Guiana and Suriname. It lives in the deep rainforest, in silk-lined burrows and under rocks and roots.

If they need to defend themselves, they rub hairs together to create a hissing noise loud enough to be heard 15 feet away. They can also let their hairs loose and fling them at attackers. The goliath bird-eating spider may also rear up on its hind legs to show its large fangs as a further defense strategy. If they need to defend themselves, they rub hairs together to create a hissing noise loud enough to be heard 15 feet away. They can also let their hairs loose and fling them at attackers. The goliath bird-eating spider may also rear up on its hind legs to show its large fangs as a further defense strategy.

After their maturation molt, males develop a "finger" on the underside of the first set of front legs that is used to hook and lock the female's fangs and to steady themselves while they mate. After mating, males die within a few months.

The female must have recently molted in order to reproduce, or acquired sperm will be lost during the molt. Once mated, the female makes a web in which she lays 50 to 200 eggs that become fertilized as they pass out of her body. The female then wrap the eggs into a ball, and, unlike other species of tarantula, the female carries the egg sac with her. Egg sacs are almost the size of a tennis ball and contain around 70 spiderlings.

In order to grow, they must go through several molts. Molting is the process by which the tarantula sheds its old exoskeleton and emerges in a new, larger one. Spiderlings can be expected to molt five or six times in their first year. They take around two to three years to reach maturity.

Credit : Smithonian National Zoo

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Sun bear is the smallest of all bears, inhabiting the rainforests of Southeast Asia. Its body is covered with short, but coarse fur that can be brown, black or grey. There is a U-shaped patch of white on the chest, which looks like the rising sun.

Its unique feature is its very long tongue (20-25cm long). This helps them extract honey from beehives and also earning it the nickname honey bear.

It does not hibernate but build nests of twigs and leaves in trees to sleep in. It eats insects, leaves, lizards, and berries. But its favourite snack is honey.

Sun bears don’t appear to have a defined breeding season and generally give birth to one cub. Cubs are born in dens or in hollow trees and are blind and helpless at first. At around 2 months, they are capable of moving about and weaning takes place at around 4 months. Parental care is important in the early life of cubs and they remain with their mothers for 2 years or more after birth.

With estimated population declines of over 30% over the past 30 years, sun bears are classed as Vulnerable on the IUCN Red List of Threatened Species. Sun bears occupy just a fraction of their former range, having been extirpated from many areas it originally occupied.

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Serval is a wild cat native to Africa. It has a yellowish to orange fur covered in black spots. Some of the spots blend together to give them the appearance of stripes. It has a long neck, big ears and long legs.

It is one of the best hunters in the wild cat kingdom.

Its success rate is 50%, while other cat species have only 10% success rate. It hunts both during the day and night. Its predators are leopards, hyenas and dogs. Humans kill them for fur. Cubs are blind at birth and weigh only 250 gram. They will open their eyes and double their size in two weeks.

Unfortunately, as with most carnivores, serval populations are at risk. They are not only suffering from loss of habitat, but they are also destroyed when suspected of killing domestic fowl. 

Servals are important small hunters that, unlike large carnivores, eat a wide variety of smaller prey, such as rodents and birds. Because the over-population of rodents poses such a direct threat to the environment and agricultural crops, servals and other small carnivores are extremely important to the balance of many ecosystems.

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The tench is a large, hardy olive green-coloured fish native to Europe. Found in lakes and rivers, its skin secretes a lot of slime. Also known as doctor fish, its slime is believed to have healing properties. The slime was once used on humans to treat wounds.

Tench prefer shallow lakes, rivers, and backwaters with a great deal of vegetation. In some parts of the world, they spend the winter buried in mud.

To find food, the tench uses short sensory organs that protrude from each side of its mouth, called barbels, to search the river or lake bottom for snails, mosquito larvae, and other small creatures. Tench also eat detritus, algae, and plant matter.

Male tench reach maturity at around two to three years old, females about a year later. That happens in late spring or summer when the female releases her eggs every 15 days or so until the temperature cools. She does this near plants so that the sticky eggs attach to the vegetation. One or two males will swim by and release sperm. Once the eggs hatch, the larvae stay attached to the plants for several days before swimming off.

In Europe, tench are threatened by the alteration of waterways and other kinds of river engineering.

Credit : National Geographic

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Did you know a black tarantula has been named after legendary American singer, songwriter and actor Johnny Cash? Scientifically called "Aphonopelma johnnycashi", this tarantula was discovered in 2015 near Folsom Prison, California. It was named after Cash in honour of his song Folsom Prison Blues."

The spider doesn't sing, but it's black and can be found near the California prison that was the setting of Cash's "Folsom Prison Blues."

The researchers also collapsed the number of U.S. species from 55 to 29, including Aphonopelma johnnycashi and Aphonopelma atomicum—named, with a wink to "Tarantula" and other sci-fi B movies, because it was collected near the atom bomb test site in Nevada.

"This is unequivocally the most important work on tarantulas ever done. It sets an incredibly high standard for taxonomy which few will be able to attain," Robert Raven of Australia's Queensland Museum wrote in an email after reading the paper.

The 340-page study by biologists Chris Hamilton and Jason Bond of Auburn University and Brent Hendrixson of Millsaps College "will be referenced for many many years," Raven said.

Credit : phy.org 

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Some fish do, while others, such as some sharks, don't. In humans and many land mammals, sleeping would mean eye closure and the presence of typical patterns of electrical activity in the brain, including the neocortex. But fish lack eyelids and a neocortex. So, the fish that sleep do not sleep in the same way that land mammals do, they simply rest with their eyes open.

Researches show that fish may reduce their activity and metabolism while remaining alert to danger. Some fish float, some stuff themselves into a secure spot in the mud or coral, and some even locate a suitable nest. These periods of suspended animation are comparable to that of sleep in people. The nature of fish "sleep" is still an area of active research.

What about shark? There are over 400 species of sharks. Some need to move pretty much all the time to keep water moving over their gills so that they can breathe. These sharks are obligate ram ventilators. These include the great white, the mako and the whale shark. Though there have been some accounts that vouch that these sharks too rest, such 'sleep' has not been confirmed through studies.

Many fish species, such as bluefish, Atlantic mackerel, tuna, and bonito, also swim continuously and do not show signs of sleep.

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The leaf sheep, a species of sea slug, is the only non-plant organism in the world that performs photosynthesis.

Costasiella kuroshimae grows up to 8 mm in length, and is found near Japan, Indonesia and the Philippines. Its appearance makes it look like the cartoon sheep character Shaun the Sheep. It has two dark eyes, dotted green cerata on its body, and two rhinophores on its head with fine hairs that sense chemicals in the water, enabling it to find food sources. It spends its whole life on the algae Avrainvillea. In a process called kleptoplasty, it sucks the algae's chloroplasts (structures within the algae's cells that contain chlorophyll, a green photosynthetic pigment) and keeps them within its cerata, enabling it to perform photosynthesis. This ability has earned the leaf sheep the title of "solar-powered sea slug".

Unfortunately, the leaf sheep are native to the waters around Japan, which means they’ll be hard to see for many of us. Although, in the eastern emerald elysia, another sea slug belonging to the clade, Sacoglossa, resides along the east coast of the U.S. The eastern emerald elysia, like the leaf sheep, can perform photosynthesize light into food. Although it’s not nearly as cute.

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In September 2021, bioscience and genetics company Colossal announced that it has raised $15 million for its ambitious project to bring the woolly mammoth back to the Arctic tundra. The company is co-founded by Ben Lamm, a tech and software entrepreneur, and George Church, a professor of genetics at Harvard Medical School who has pioneered new approaches to gene editing. Scientists have set initial sights on creating the elephant-mammoth hybrid, with first calves expected in six years.

The project is framed as an effort to help conserve Asian elephants by equipping them with traits that allow them to thrive in vast stretches of the Arctic known as the mammoth steppe. But the scientists also believe introducing herds of elephant-mammoth hybrids to the Arctic tundra may help restore the degraded habitat and combat some of the impacts of the climate crisis. For example, by knocking down trees, the beasts might help to restore the former Arctic grasslands.

Not all scientists suspect that creating mammoth-like animals in the lab is the most effective way to restore the tundra. “My personal thinking is that the justifications given – the idea that you could geoengineer the Arctic environment using a herd of mammoths – isn’t plausible,” said Dr Victoria Herridge, an evolutionary biologist at the Natural History Museum.

“The scale at which you’d have to do this experiment is enormous. You are talking about hundreds of thousands of mammoths which each take 22 months to gestate and 30 years to grow to maturity.”

Lamm said: “Our goal isn’t just to bring back the mammoth, but to bring back interbreedable herds that are successfully rewilded back into the Arctic region.”

Whether Asian elephants would want to breed with the hybrids is, for now, unknown. “We might have to give them a little shave,” said Church.

Gareth Phoenix, a professor of plant and global change ecology at the University of Sheffield, said: “While we do need a multitude of different approaches to stop climate change, we also need to initiate solutions responsibly to avoid unintended damaging consequences. That’s a huge challenge in the vast Arctic where you have different ecosystems existing under different environmental conditions.

“For instance, mammoths are proposed as a solution to help stop permafrost thaw because they will remove trees, trample and compact the ground and convert landscapes to grassland, which can help keep the ground cool. However, we know in the forested Arctic regions that trees and moss cover can be critical in protecting permafrost, so removing the trees and trampling the moss would be the last thing you’d want to do.”

Credit : The Guardian 

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After an epic 17-month journey that made international headlines, China's famous herd of 14 wandering Asian elephants finally began heading home in August 2021. They had left their natural reserve in Pu'er city in Yunnan province, and the return covered a more-than-500-km trek. The highlights of their trip included the birth of a calf and visuals of their nap going viral. As adorable as it sounds, the stark reality is that "large-scale human engineering developments have exacerbated the ‘islanding’ of elephant habitats".

The elephants were also monitored and kept away from residential areas by a team of eight people, who tracked them on the ground and by drone for 24 hours a day.

Local wildlife experts have been unable to pinpoint the reason the herd decided to move. But Zhang Li, a professor on mammal conservation at Beijing Normal University, told the state-run Global Times in June that “Large-scale human engineering developments have exacerbated the ‘islanding’ of elephant habitats.”

This meant “the traditional buffer zones between humans and elephants are gradually disappearing, and the chances of elephants’ encountering humans naturally increase greatly,” he said.

The tourists’ behaviour wasn’t welcomed by all, with some locals complaining that the elephants had eaten entire fields of corn and truckloads of pineapples. A car dealer in Eshan county reported in June that six visiting elephants had drunk two tonnes of water in his shop.

Others monitored the news for incidents that might pose a threat to the animals. In July, the Australian Broadcasting Corporation reported that Yunnan authorities had warned locals to avoid poisonous mushrooms growing during the wet season. Soon, the topic “Will elephants eat the poisonous mushrooms” began trending on Weibo, eventually being viewed more than 120m times.

The elephants were also used as state propaganda, starring in an editorial published by the Global Times titled, “China’s care for wandering elephants mirrors adorable national image the West can’t distort.”

Credit : The Guardian 

Picture Credit : Google

The eyes of the Arctic reindeer change colour with the seasons, from golden in the summer to a deep blue in winter. The part that changes colour is the tapetum lucidum - a mirrored layer behind the retina. The interminable Arctic winter forces

the reindeers' pupils to dilate for months to allow more light in; pressure in the eye increases, preventing fluid from draining naturally. This compresses the tapetum's collagen fibres, which in turn makes it reflect shorter wavelengths, notably the blue light common in Arctic winters. In summer, with the usual gaps between the fibres, the tapetum reflects yellow wavelengths. The technique allows the reindeer to make the most of changing light levels in their extreme habitat.

In dark conditions, muscles in your irises contract to dilate your pupils and allow more light into your eyes. When it’s bright again, the irises widen and the pupils shrink. The same thing happens in reindeer, but the interminable Arctic winter forces their pupils dilate for months rather than hours. Over time, this constant effort blocks the small vessels that drain fluid out of the eyes. Pressure builds up inside the eyeballs, and they start to swell. “The animal’s moving towards glaucoma,” says Jeffery.

These events also change the tapetum. This layer is mostly made up a collagen, a protein whose long fibres are arranged in orderly rows. As the pressure inside the eye builds up, the fluid between the collagen fibres gets squeezed out, and they become more tightly packed. The spacing of these fibres affects the type of light they reflect. With the usual gaps between them, they reflect yellow wavelengths. When squeezed together, they reflect… blue wavelengths.

Credit : National Geographic Society 

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On July 29, 2021, International Tiger Day, the Prime Minister tweeted that "India achieved the target of doubling of tiger population four years ahead of schedule and that the country is home to 51 tiger reserves spread across 18 states" and "to over 70% of the tiger population globally. While this was great news, it was also of concern that threats such as poaching, habitat degradation, and human-wildlife conflict continued to exist.

The Prime Minister said that the last tiger census of 2018 showed a rise in the tiger population. "India is home to 51 tiger reserves spread across 18 states. The last tiger census of 2018 showed a rise in the tiger population. India achieved the target of doubling of tiger population 4 years ahead of schedule of the St. Petersburg Declaration on Tiger Conservation," he tweeted.

He further said that India's strategy of tiger conservation attaches topmost importance to involving local communities.

"We are also inspired by our centuries-old ethos of living in harmony with all flora and fauna with whom we share our great planet," PM Modi added. The Saint Petersburg declaration on tiger conservation was signed in 2010. In the meeting, it was decided to celebrate July 29 as Global Tiger Day across the world to create awareness on tiger conservation.

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In May 2021, genetic tests confirmed that a giant tortoise found on the Galapagos Islands is from a species that scientists thought had died out more than a century ago. The single female Fernandina giant tortoise was discovered during a 2019 expedition to Fernandina Island. To prove the link, scientists took samples from the female to compare to the remains of a male from the species Chelonoidis phantasticus. The last previous sighting of the species had been in 1906.

A giant tortoise (Geochelone hoodensis) population that in the 1970s had dropped to about 15 was once again a common sight on the island, said Washington Tapia, a park official who led the survey, which used electronic devices to track the animals. “During the expedition we found nests, recently hatched tortoises, and adults born on Española, which indicates that the tortoise population is doing well.”

The population now numbered between 1,500 to 2,000, said Linda Cayot, a scientific adviser to Galápagos Conservancy. “We will have a much better idea when the survey results are compiled.”

The original population was thought to number up to 5,000 before becoming a vulnerable source of fresh meat for passing sailors.

The project’s success has bolstered a plan to “re-tortoise” another island, Pinta, with the same species in the hope of re-creating a “pre-human” balanced ecosystem. The scattering of rocky, volcanic islands 600 miles west of mainland Ecuador are a Unesco world natural heritage site and home to dozens of endemic species found nowhere else. Some 95%  of the territory’s 3,000 sq miles is a protected area.

“It’s completely amazing, one of the few places where you can actually see evolution happening in real time,” said Henry Nicholls, ambassador for the Galápagos Conservation Trust. He welcomed the recovery of Española’s giant tortoise population. “They are a flagship species which capture the public imagination.”

Credit : Our World

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Scientists at the Zoological Survey of India (ZSI) discovered a new species of shrew-Crocidura narcondamica-from the Narcondam volcanic island in the Andaman and Nicobar conglomerate nestled in the Bay of Bengal, according to an article published on May 3, 2021 in the journal Nature. A media report in August 2021 said that India added 557 new species to its fauna, which included 407 new species and 150 new records, as revealed by Animal Discoveries 2020, a document published by the 251. The number of faunal species in India climbed to 1,02,718 with the discovery of the new species.

The new species is of medium size (head and body lengths) and has a distinct external morphology with darker grey dense fur with a thick, darker tail compared to other species of the genus, Dr. Sivaperuman added. He also said craniodental characters of the species such as braincase was rounded and elevated with weak lambdoidal ridges makes the species distinct in comparison to other close congeners.

The discovery of a new insectivorous mammal comes after 43 years. Prior to this, scientists from the ZSI had discovered Crocidura jenkinsi on the South Andaman Island in 1978.

The discovery comes from one of most remote and uninhabited islands, Narcondam island, of the Andaman and Nicobar archipelago. Narcondam Island is located about 130 km east of North Andaman, and about 446 km of the west coast of Myanmar. The isolated island covers an area of 6.8 km2 and the highest peak (volcanic cone) is 710 m above sea level; however, the base lies approximately 1,500 m beneath the sea. This thickly vegetated island is bordered by cliffs on the southern side and crested by three peaks is part of a volcanic arc that continues northward from Sumatra to Myanmar.

Credit : The Hindu 

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