My Science School

Echinoderm is a variety of invertebrate marine animals belonging to the phylum Echinodermata. They are characterized by a hard, spiny covering or skin.

The adults are recognizable by their (usually five-point) radial symmetry, and include starfish, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. 

The echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. Most echinoderms are able to reproduce asexually and regenerate tissue, organs, and limbs; in some cases, they can undergo complete regeneration from a single limb. Geologically, the value of echinoderms is in their ossified skeletons, which are major contributors to many limestone formations, and can provide valuable clues as to the geological environment. They were the most used species in regenerative research in the 19th and 20th centuries. Further, some scientists hold that the radiation of echinoderms was responsible for the Mesozoic Marine Revolution.

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Reptiles are air breathing vertebrates covered in special skin made up of scales, bony plates, or a combination of both.

They include crocodiles, snakes, lizards, turtles, and tor- toises. All regularly shed the outer layer of their skin. Their metabolism depends on the temperature of their environment.

Unlike birds and mammals, reptiles do not maintain a constant internal body temperature. Without fur or feathers for insulation, they cannot stay warm on a cold day, and without sweat glands or the ability to pant, they cannot cool off on a hot one. Instead, they move into the sun or into the shade as needed. During cooler parts of the year they become inactive. Because of their slow metabolism and heat-seeking behavior, reptiles are cold-blooded.

Reptile reproduction also depends on temperature. Only boas and pythons give birth to live young. The other species lay their eggs in a simple nest, and leave. The young hatch days to months later. The soil temperature is critical during this time: It determines how many hatchlings will be male or female. Young reptiles can glide, walk, and swim within hours of birth. Reptiles first appear in the fossil record 315 million years ago and were the dominant animals during the Mesozoic era, which lasted for 270 million years until the extinction of the dinosaurs.

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Amphibians are small vertebrates that need water, or a moist environment, to survive. All can breathe and absorb water through their very thin skin.

Amphibians are a class of cold-blooded vertebrates made up of frogs, toads, salamanders, newts, and caecilians (wormlike animals with poorly developed eyes). All amphibians spend part of their lives in water and part on land, which is how they earned their name—“amphibian” comes from a Greek word meaning “double life.” These animals are born with gills, and while some outgrow them as they transform into adults, others retain them for their entire lives.

Amphibians are the most threatened class of animals in nature. They are extremely susceptible to environmental threats because of their porous eggs and semipermeable skin. Every major threat, from climate change to pollution to disease, affects amphibians and has put them at serious risk.

Amphibians lay jelly-covered eggs, called spawn, usually in still, fresh water, often among water plants. The resulting young, known as tadpoles - which at first look like legless blobs with tails - are aquatic and have feathery, external gills, but soon develop lungs and legs and leave the water. Adult amphibians spend most of their life on land, usually in damp habitats, only returning to the water to breed in the spring. A few species may be found in water at almost any time of year.

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Arachnida is a class of joint-legged invertebrates with segmented bodies, tough exoskeletons, and joint appendages. Arachnida includes orders containing spiders (the largest order), scorpions, ticks, mites, harvestmen, and solifuges.

Almost all adult arachnids have eight legs, unlike adult insects which all have six legs. However, arachnids also have two further pairs of appendages that have become adapted for feeding, defense, and sensory perception. The first pair, the chelicerae, serve in feeding and defense. The next pair of appendages, the pedipalps, have been adapted for feeding, locomotion, and/or reproductive functions. In Solifugae, the palps are quite leg-like, so that these animals appear to have ten legs. The larvae of mites and Ricinulei have only six legs; a fourth pair usually appears when they moult into nymphs. However, mites are variable: as well as eight, there are adult mites with six or even four legs.

Like all arthropods, arachnids have an exoskeleton, and they also have an internal structure of cartilage-like tissue, called the endosternite, to which certain muscle groups are attached. The endosternite is even calcified in some Opiliones.

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Marsupials are mammals that carry their young in a pouch attached to their body.

Marsupials have a short-lived placenta that nourishes their young for just a few days before they’re born, the rest of their nutrition coming from the mother’s teats inside the pouch. Instead of the placenta, the mother’s milk nourishes the young and allows it to grow and develop.

Although the word ‘marsupial’ comes from the Latin word ‘marsupium’, which means pouch, not all marsupials have pouches. The pouch is designed to protect the offspring while they suckle on the nipples, however some in some species this is just a fold, not something the young can fit inside for their joey stage of development.

Marsupials have an extra pubic bone, the epipubic bone, to support their pouch.

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A blue whale is the largest known animal, found in oceans around the world, except the Arctic.

It grows up to 110 feet in length and 150 tonnes in weight. Did you know its tongue alone can weigh as much as an elephant?

Its diet consists exclusively of krill, which are tiny shrimp-like creatures. It eats tonnes of them at times.

They spend summers feeding in polar waters and undertake long migrations towards the Equator as winter arrives.

It makes a range of sounds to communicate and navigate. It is among the loudest animals on the planet.

These marine marvels are a species of ‘baleen’ whale. Instead of teeth, they have baleen, a fibrous material used to filter their food. When eating, the whale lets a huge volume of water and krill into its mouth. It then pushes the water through its 300-400 baleen plates, which trap the tasty grub to be swallowed. Gulp!

Sadly, in the late 19th early 20th century, blue whales were heavily hunted. And despite a global hunting ban in 1966, their population has declined by 70-90 percent in the past 150 years. With only 10,000-25,000 left in the wild, these magnificence marine mammals are today classified as an endangered species.

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Praying mantis, a large group of insects found in tropical and temperate habitats.

Most of them are ambush predators. It uses its spiked forelegs to grasp its prey. Moths, crickets, grasshoppers and flies are its favourite food. But larger species in its family (mantidae) even prey on lizards.

It earned its common name – praying mantis, because of the way its front legs are bent and held together at an angle that suggests the position of prayer.

It has triangular heads on along thorax. Did you know it can turn its head 180 degrees to scan its surroundings?

Try to sneak up on a praying mantis, and you may be startled when it looks over its shoulder at you. No other insect can do so. Praying mantids have a flexible joint between the head and prothorax that enables them to swivel their heads. This ability, along with their rather humanoid faces and long, grasping forelegs, endears them to even the most entomophobic people among us.

The female praying mantis deposits her eggs on a twig or stem in the fall ?and then protects them with a Styrofoam-like substance she secretes from her body. This forms a protective egg case, or ootheca, in which her offspring will develop over the winter. Mantid egg cases are easy to spot in the winter when leaves have fallen from shrubs and trees. But be forewarned! If you bring an overwintering ootheca into your warm home, you may find your house teeming with tiny mantids.

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We all see squirrels scurrying about on trees or climbing wires. These rodents move with remarkable agility, and jump from one building to another or from one tree to another with such swiftness that sometimes we perhaps do wonder if they'd have a fatal fall. Apparently, squirrels don't usually fall to their deaths. So what protects them? Come, let's find out.

To understand the protection that squirrels have, we have to get into a bit of physics. When any object or living being falls-from any height - there are two forces at play. One is gravity, the force that pulls any object to Earth, and the other is drag or air resistance, the force that air pushes against a moving object. The latter acts in the opposite direction of the falling object, and tries to slow it down. While the force of gravity remains constant through the falling, the force of air resistance increases with increasing speed. As this continues to happen, the force of air resistance finally equals the force of gravity. This is called terminal velocity, and it is the speed when the object cannot full faster the speed stabilises.

Now, we know that usually heavier and larger objects experience greater pull of gravity. But squirrels being small and light, their force of gravity is very low, and thanks to their "stretchy bodies and puffy tails, they experience a lot of air resistance. So, when the air resistance finally matches the low gravity during a fall, the terminal velocity is very low too. At such a low speed, the fall does not become fatal for the squirrel.

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Did you know wood frogs can freeze without actually dying? When temperatures dip to 0 degrees Celsius, ice starts to form on their skin. Two-third of their body water becomes ice. As a wood frog starts freezing, its heart continues to function to distribute glucose (a cryoprotectant) throughout its body to promote freeze tolerance. The heart slows down and stops with the completion of ice formation. The wood frog survives frigid winters like this, and when spring arrives and temperatures warm, it thaws out and hops away.

Most frogs survive northern winters by hibernating deep under water, in ponds, lakes and streams—they are cold and dormant but their body temperature never falls below freezing.

Wood frogs have a different strategy. They hibernate by nestling down into the leafy litter on the forest floor. The leaves, duff and overlying snow give some insulation from extreme cold, but the frogs are not protected from subfreezing temperatures as they would be if they chose the underwater strategy.

Researchers have found that wood frogs spend the winter frozen! This amazing strategy allows wood frogs to become active very early in spring, because the land thaws and warms more quickly than the ice-covered lakes The newly active frogs can mate and lay eggs in small ponds and even in melt water pools that dry up by midsummer. By contrast, frogs that hibernate underwater take longer to become active, so they must breed later. These frogs need permanent water that won’t dry out.

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Sea otters hold hands while sleeping so as to avoid drifting away from each other or from the rest of their group. Usually, a mother and her pup adopt this method to avoid getting separated. They also sleep, wrapping themselves in kelp or giant seaweed growing from the seafloor to remain anchored in one place.

Otter fur is expensive, and the animal is often hunted. When they hold hands with another otter, they can remain away from land, making it harder for hunters to kill them.

The fur of an otter is thick, and as the otter sheds, it is replaced gradually rather than in a specific season. Their fur helps them stay buoyant in the water, so they must keep their fur clean to give them this natural buoyancy. 

Otters spend a lot of their time grooming. They spend time cleaning the fur, untangling knots, removing any loose hair, and rubbing the coat to squeeze out any excess water. They also introduce air into the fur by blowing air directly into their coat.

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Snakes are found on every continent except Antarctica. They are also absent from islands in the Arctic region such as Iceland and Greenland. Reptiles such as snakes are cold-blooded, meaning they depend on external heat sources in the environment to keep themselves warm. Antarctica is the coldest continent on Earth; and as it remains frozen throughout the year, snakes cannot survive there.

Snakes belong to the animal class reptiles.  This group also includes crocodiles, lizards, and turtles.  Reptiles are cold-blooded animals that raise their body temperature by lying in the sun or lower it by crawling into the shade.  Their body temperature changes to the temperature of its surroundings.  Because of this, snakes that live in colder climates must hibernate through the winter.  They will find burrows or caves and fall into a deep sleep until the weather becomes ware enough for them.

There are more than 2,900 species of snakes in the world.  They live almost everywhere, in deserts, forests, oceans, streams, and lakes.  Snakes live on the ground, in trees, and in water.

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Turtles can live in water or land, whereas tortoises are land animals and not equipped for water.

A tortoise has a dome-shaped shell and short and sturdy feet. Its legs are bent instead of being straight and directly under the body. A turtle has a flat, streamlined shell and limbs that are quite similar to a tortoise's, but the turtle's feet are webbed and have long claws which provide a good grip upon floating logs and help the reptile climb onto riverbanks. Some turtles might even have flippers, as is the case for the pig-nosed turtle.

The shells that cover the body of these reptiles are very important as they give researchers a fair idea of how these reptiles live. As turtles generally prefer to live in water, the shell of a turtle is flat and streamlined to aid in swimming and diving, while the shell of a tortoise, which lives on land, is rather large and dome-shaped to provide protection from predators. Also, the shell of a tortoise is quite heavy when compared to a turtle's shell, which is lighter to avoid sinking and to increase swimming speed.

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There are turtle tunnels in Japan to protect wandering turtles from being run over by trains. Seeing turtles getting trapped while crossing rail tracks to get to a pond nearby, Japan railway engineers installed shallow tunnels beneath the tracks at stations in Nara Prefecture in 2015.

Every year, these slow-moving reptiles get stuck on the tracks, causing delays in the arrival schedule. What's more, as you can see in the photos provided by the railway company, the animals can cause train accidents by getting wedged between the lines at junctions. When the switches flip, they fail to close completely due to the turtles' shells.

It's a common problem too, as the animals that were unable to climb over the metal rails follow along the tracks until they get stuck or killed by the trains. The West Japan Railway fixed this problem by installing escape ditches for the turtles at set intervals along the railroad.

Since installing the system in April, the company says it's witnessed ten turtles in the ditches. That doesn't sound like a lot, but ten animals saved and ten potential accidents avoided is great.

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Hippopotamuses are sedentary creatures that spend most part of the night eating and most part of the day cooling off in water. Though they eat up to 40 kg of grass at night, from time to time they also have to venture out in the sun to snack. But their skin is very sensitive to both drying and sunburn and that's why they produce their own sunscreen, in the form of a sticky reddish fluid. Some people call this "blood sweat," but it is neither blood nor sweat.

Unlike sweat, which humans and some animals secrete onto their skin, where it evaporates and therefore cools the body, this fluid functions as a skin moisturizer, water repellent and antibiotic.

The 'sunscreen' is made up of two pigments-one red, called hipposudoric acid; and the other orange, called norhipposudoric acid. While both pigments act as sun blocks, hipposudoric acid also discourages the growth of bacteria.

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An earthquake is a natural phenomenon, one that can leave inexplicable devastation in its wake. As with a few other destructive natural phenomena such as cyclones, it would certainly be useful to be alerted about an earthquake beforehand. Sure, there are earthquake early warning systems. But they don't "predict earthquakes, they just "detect ground motion as soon as an earthquake begins and quickly send alerts that a tremor is on its way, giving people crucial seconds to prepare". But there's been so much talk about animals being able to "predict" earthquakes. Is that true? Come, let's find out. Now and then we hear about strange animal behaviour just before an earthquake - animals or pets fleeing the place or getting restless. A U.S. earthquake in 1989 is said to have been "predicted" by a geologist who gathered data to show that "a larger than usual number of household pets were listed as missing in the week or so before" the quake. However, only a year before that a study spanning three years had showed no correlation between missing pets and earthquake. Meanwhile, as recently as 2015, a new study by research scientist Friedemann T. Freund and team said that "animals in Peru's Yanachaga National Park basically disappeared in the weeks leading up to a 7.0 magnitude quake in the region in 2011". However, Freund's long-held theory - that there are changes to the magnetic field before a quake that animals can sense - has been questioned by the scientific community. There's something that animals may be able to sense, though-seismic waves.

The first of an earthquake's seismic waves is the P-wave (pressure wave), which arrives before the S-wave, the secondary, shaking wave. Animals may sense the P-wave, which could explain their unusual behaviour. Further, some animals, such as elephants, are said to perceive low-frequency sound waves and vibrations from foreshocks that humans cannot detect. A most recent study, conducted on a farm in an earthquake-prone region in Italy and published last year, recorded the movements of cows, sheep, and dogs over several months. It discovered that "the animals were unusually restless in the hours before the earthquakes. The closer the animals were to the epicentre of the impending quake, the earlier they started behaving unusually". The study states that the effect was clear only because all the animals were studied together, and may not have been easy to spot at an individual level. While studies show that animals can perhaps sense an impending earthquake, it is said that extensive research across geographies is required to understand this better.

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