My Science School

Beaver is among the largest rodents in the world. There are two species of beavers: American and Eurasian.

It has thick fur, webbed fur, webbed feet and scale-covered tails. It is a semiaquatic species, which can swim 5 miles per hour and spend 15 minutes underwater without returning to the surface for air.

It uses its powerful jaws and strong teeth to fell trees and build homes and dams, which acts as channels to control the flow of water in a stream or lake.

It eats leaves, roots, and bark from aspens, willows, maples and poplar trees. It also eats aquatic plants.

All beavers need water to survive. They live in or around freshwater ponds, lakes, rivers, marshes and swamps. American beavers live throughout North America, but stay clear of deserts and the far northern areas of Canada. Eurasian beavers once lived all over Europe and Asia. Now, they only live in small numbers throughout southern Scandinavia, Germany, France, Poland, and central Russia due to overhunting.

Beavers don’t just build homes from trees, they also eat them. Unlike other mammals, beavers can digest cellulose, which is a major component of their diet, according to ADW. Beavers eat leaves, roots and bark from aspens, willows, maples and poplar trees. They also eat aquatic plants. 

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The caterpillar of the elephant hawk moth from Brazil mimics a snake to defend itself from predators. When alarmed, the crawler flips, retracts its legs and head, and puffs up its thorax or the front part of its body to appear like the head of a snake. It has two pairs of eye spot markings on its body.

If the "deadly" costume isn't enough to deter a predator, the caterpillar might also strike to enhance the effect. 

While many animals use eyespots to draw predators' attention away from the head (a tactic known as deflection), a snake mimic caterpillar's false face is actually located on the same end as its real one. 

"Deflection might not work well for a caterpillar because the caterpillar probably won’t survive if any part of its body gets pierced or ripped off by an attacker," explains eyespot expert Dr Thomas Hossie. "This defence is all about intimidating or startling an attacker who will run (or fly) away instead of risk a lethal encounter with a snake."

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Wombats are the only animals in the world whose poop is cube-shaped. These burrowing marsupials, which are native to Australia, mark their territories with their poop whose shape prevents it from rolling away. It is said that the varying elasticity of their intestines help shape their cubic scat.

But how does such sharp-sided scat come from a round anus?

To get to the bottom of the mystery, scientists dissected a wombat that had died after being hit by a car. They examined the intestines and found that they contain two grooves where the guts are more elastic, which the team first reported in 2018.

In the new study, the researchers dissected two further wombats and tested the guts’ layers of muscle and tissue, finding regions of varied thickness and stiffness. They then created a 2D mathematical model to simulate how the regions expand and contract with the rhythms of digestion. The intestinal sections contract over several days, squeezing the poop as the gut pulls nutrients and water out of the feces, the team reports today in the Royal Society of Chemistry's aptly titled journal Soft Matter.

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Cows are ruminants (cud-chewing herbivores) and they do not have upper front teeth. They have what is called a hard, leathery dental pad in the place of upper incisors. They use their tongue to grasp the grass and pinch it off using their dental pad and lower incisors. But they have molars on the upper and lower jaw for grinding up food.

Let’s explore how cows are able to eat grass. The key to this ability lies in the stomach. After we chew and swallow our food, the stomach serves as a holding tank where digestion begins and food starts being separated into individual nutrients. Next, food passes into the small intestine where the breakdown continues and where the body absorbs nutrients. This basic digestive process is also true of cows, but there are a few extra steps along the way.

Cows are unique in that they have fewer teeth than other animals. In the front of the mouth, teeth (known as incisors) are only located on the bottom jaw. In place of the top incisors, there is a hard leathery pad (known as the “dental pad”). In addition, cattle have a relatively immobile upper lip (compared to goats and sheep). Because of this unique oral anatomy, a cow uses its tongue to grasp a clump of grass and then bite it off. Teeth in the back of the mouth (known as molars) are located on the top and bottom jaws. Plant materials sometimes contain tough stems, but because a cow chews food in a side-to-side motion, the molars shred the grass into small pieces that are more easily digested. 

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It is commonly believed that when an earthworm is cut in half-crosswise, it regenerates into two new worms. But this is not true. Earthworms do have the ability to regenerate lost segments. This ability varies between species and depends on the extent of the damage. They have a distinctive head and tail. They also have clitellum, a glandular and non-segmented section of the body wall, near the head. It secretes a sticky sac in which their eggs are deposited. When cut behind this clitellum, the head of the earthworm may survive and grow the tail, but the tail does not grow a head. The tail will die.

Some earthworms may amputate their tail when grasped by a predator. The tails would still move and distract their attacker. Species Eisenia fetida accumulates waste in its tail and when it cannot store any more, it amputates the tail. But none of these earthworm species grow head.

Amazing flatworm

However, there is a type of worm which can regenerate both head and tail. It's a primitive worm, called the planarian flatworm, common to many parts of the world, living in ponds and rivers.

A planarian split lengthwise or crosswise will regenerate into two separate individuals. When cut into three, even the middle part grows both new head and tail. The worm has extraordinary regeneration capacity that it can reform its entire body from just 1/277th of its original body size. When planarian regrows its head, it even keeps its old memories intact. In 2017, an amputated planaria was sent aboard the International Space Station (ISS). After spending five weeks, it regenerated into a double-headed worm.

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Do you know what keeps marine creatures such as seals, whales, and walruses warm in the chilly waters they inhabit? Blubber. It is a thick layer of fat right under the skin of marine mammals, and covers their entire body, except for their fins, flippers, etc. In addition to insulating the animals, it stores energy and increases buoyancy. So one can imagine how integral the blubber is to these mammals existence. But the sea otter, among the smallest of marine mammals, has no blubber at all. And how it stays warm has been a mystery.

Otters are found on all continents, except Australia and Antarctica. They inhabit both freshwater systems such as rivers, lakes, and wetlands, and marine ecosystems. The sea otter is found in the Pacific Ocean. It has been known all along that the sea otter's thick and water-resistant fur offers it some help with heat loss. But that isn't enough to protect itself from the cold water of Alaska, where a lot of these otters reside. Scientists also knew "the sea otters burn a lot of energy - approximately three times greater than predicted for mammals of their size, and to keep up with the demand, they may consume up to 25 percent of their body mass in a day". But what they could not find out was "which tissues were making use of this energy and how it was going towards producing heat".

And that is what a new paper published in a journal discloses - these creatures have a unique energy conversion system whereby their muscle tissue "leak" large amounts of heat throughout their bodies. Normally, a living creature's metabolism rate is linked to its activity level. In the case of a sea otter, the metabolism is high but without much activity. So this metabolic energy is being lost as heat rather than being used for powering its muscles. As a news report quotes the lead author of the paper, "they're really good at making heat by being inefficient. The team behind the study found that this "thermogenesic effect was present in sea otters from the time they were babies to adults.

Apparently, this effect is presumed to be prevalent among animals in the polar regions, but seen for the first time in these marine creatures. The study's lead author also imagines that understanding this metabolic system could help find solutions to obesity in humans.

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At 850,000 to 1 million hairs per square inch, sea otters (Enhydra lutris) have the thickest fur of mammal. Their fur any consists of two layers, an undercoat and long, waterproof guard hairs. As marine mammals without any fat to keep them warm, this double-layer system traps air next to their skin, preventing it from getting wet and protecting them from chilly ocean waters.

To add air to their undercoat sea otters will lay on their backs in the water and tilt their head down toward their stomach where they then blow air into their fur. In addition to staying warm, this helps increase buoyancy that can help the sea otter swim heavier objects up from the bottom of the ocean. Sea otter pups are born with a special coat that acts like a lifejacket and prevents them from being able to dive. At two months old the pup sheds this special coat.

The special qualities of sea otter fur made it a desired resource in the 18th and 19th centuries and they were hunted nearly to extinction. In response, sea otters were made one of the first marine mammals protected in the state of California in 1913. Sea otters are still a threatened species in the state of California and today 100,000 to 150,000 are protected by law.

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There are more than 16,000 species of them, varying in size and colour.

Most of them are active at night and use moon, stars and geomagnetic field to navigate. Some of their kinds are great mimics, impersonating other creatures to avoid being eaten by predators (They even mimic bird droppings!)

It is an important pollinator. It has long, curled tongue designed for diet based on nectar, fruits and berries.

While at rest, it flattens its wings against its body or spread them out (whereas butterflies usually hold their wings up)

The smallest moth in the world is the Stigmella maya, and the forewing measures just 1.2 millimetres. It is found in Yucatan in Mexico.

The largest moth in the world is the Atlas moth (Attacus atlas), with wingspan of up to 30 cm (12 inches) and a surface area of 400 square centimeters (62 square inches). It is found in the tropical and subtropical forests of Southeast Asia.

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Llama is a relative of the camel, native to South America. But unlike camels, it does not have a hump. It has long legs and neck, small head and pointed ears.

It has been used as a pack animal by locals for centuries. It can navigate rocky terrain with ease.

It is a social animal and lives in herds. When it gets annoyed, it spits. It feeds on grass and regurgitates food and chews it as cud.

In mountainous regions llamas migrate up and down mountains, moving up to higher regions when it is warm, in order to stay cooler, and moving back down in winter when temperatures start to drop. Llamas are peaceful natured hardy animals. They have excellent survival skills and their thick coats allow them to thrive in climates with extreme temperatures. The llama is the national symbol of Peru and appears on many tourist products as well as coins and stamps.

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