My Science School

Oral care experts under the ocean

'Cleaner' fish are much in demand among bigger fish. The cleaner fish are allowed to enter in through the mouth and eat up bacteria and other parasites, thus getting a meal and giving their clients a healthier mouth. However, the fish are known to engage in wrongful actions sometimes they eat mucus or scales, causing a jolt of pain to the client. The client, in return, chases the cleaner fish fiercely, giving the message! Apart from the fact that cleaner fish are too small to make a meal out of, the bigger fish face difficulty finding one. So, usually once trust has been established, the two are inseparable.

A relationship that's spot on!

Tarantulas are scary as it is - the Colombian Lesserblack Tarantula is huge, formidable and capable of eating small creatures! Yet, these mighty tarantulas spare spotted frogs. Maybe they don't taste good, but there's another reason for this special act of kindness. As mighty as they are, these tarantulas still need to protect their eggs from ants. And it turns out that spotted frogs are pretty nifty when it comes to eating up these ants, so living together offers great perks for both.

An assistant for pistol shrimp

The pistol shrimp has one mean weapon that makes other creatures jealous - rapid snapping claws! The shrimp snap their claws so rapidly that a jet of water shoots out in that direction. Despite having this weapon, nature has been cruel enough to give the shrimp lousy eyesight. That's where the goby comes into the picture. Like a guide dog leading its blind owner, the goby lets the shrimp's antennae hang onto its tail fins while it leads the way. In return, the goby gets free accommodation in the shrimp's tunnel, so all's well.

All for a sweet tooth

Meat ants have a mean reputation they're known to be violent towards other meat ants from a different territory as well as other species. Kicking, biting and spraying foul chemicals are some of their classic defence mechanisms. Yet, like everyone else, they have their weakness - a sweet tooth. What do they do to satisfy their need for sugar? They warmly welcome certain caterpillar species to their abode for the sake of the sugary fluid that the meat ants adore. In return, they even carry the caterpillars to places where plants grow so that they can feed. Talk about royal treatment!

Polar bears and arctic foxes

In the snow-filled Arctic world, finding friends and food isn't easy. So when Arctic foxes willingly join polar bears to hunt for prey, the bears don't really complain. As far as they know, the foxes don't cause any major inconvenience and the bears let them eat the scraps. The foxes are glad to get what would normally be difficult to, if they hunted by themselves.

Let's fish together

Last but not the least, dolphins work alongside fishermen! Believe it or not, without any kind of training, dolphins round up fish and alert fishermen when to throw their nets. What do they get in return? Fish that escape the net swim right into their mouths! How much better can it get? Turns out that dolphins interested in helping humans. hang out together in groups.

Picture Credit : Google 

Elephant skin can be upto 1.5 inches thick in certain places. Despite this, an elephant's skin is very sensitive, to the point where it can feel a fly land on its back. The skin is also sensitive to changes in its environment. Surprisingly it is also sensitive to the sun, and baby elephants are even known to get sunburn.

Elephant skin, unlike human skin, is resistant to shedding, so the layers – particularly the super-tough top layer, the stratum corneum -- stick around longer before sloughing off. It also has a lot more keratin (the stuff that makes up fingernails) than human skin, so it's more durable. As this thick hide is subject to everyday movement, like bending and twisting, it quickly wrinkles, with layer upon layer of wrinkly skin serving as a complex system of channels that capture and hold moisture and dirt.

So when you see elephants basking in sloppy pools, spraying water and mud to and fro, they aren't just doing it for the hilarity. The filthy goo settles into the teensy cracks in their skin, some of which are just a micrometer across, about 50 times smaller than the naked human eye can detect. Continually wetted, the skin remains permeable, helping the animals stay cooler.

Interestingly, elephant skin doesn't just randomly wrinkle — it cracks in geometric shapes that approximate other common sights in our world, from drying mud to heat-shattered asphalt, or even geometrically precise rock breakage like the Giant's Causeway in Ireland. The result is a durable cooling system that keeps these gigantic mammals from cooking in their own thick skin on steamy summer days.

Credit : How Stuff Works 

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Seals can sleep with half of their brains up and working with the other half completely asleep. This is called 'unihemispheric slow-wave sleep'. It gives a whole new meaning to the term 'sleeping with one eye open' as on the side of the brain that is asleep, the eye will close, and on the side that is awake the eye will be open!

This sleep occurs while they are in the water, but when they come up to sleep on land, they sleep with their whole brains turned off like humans.

The study's first author, University of Toronto PhD student Jennifer Lapierre, made this discovery by measuring how different chemicals change in the sleeping and waking sides of the brain. She found that acetylcholine -- an important brain chemical -- was at low levels on the sleeping side of the brain but at high levels on the waking side. This finding suggests that acetylcholine may drive brain alertness on the side that is awake.

But, the study also showed that another important brain chemical -- serotonin -- was present at the equal levels on both sides of the brain whether the seals were awake or asleep. This was a surprising finding because scientist long thought that serotonin was a chemical that causes brain arousal.

These findings have possible human health implications because "about 40% of North Americans suffer from sleep problems and understanding which brain chemicals function to keep us awake or asleep is a major scientific advance. It could help solve the mystery of how and why we sleep" says the study's senior author Jerome Siegel of UCLA's Brain Research Institute.

Credit : Science Daily 

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The mugger, also known as the marsh crocodile, is a crocodile of medium to large size with the broadest snout of all the living members of the genus Crocodylus. It lives in the Indian subcontinent as well as other countries in southern Asia. They are more alligator-like than any other crocodile, especially in their rounded snout, as most crocodiles have a snout that is pointier. Like most crocodilians, muggers feature a flat head where their eyes, ears, and nose are on top. This enables them to see, hear and breathe above water when their bodies are underwater. They have webbed feet but do not use them for swimming, using their strong, flat tail instead. “Mugger” is corruption from an Indian word that means “water monster.”

The mugger crocodile occurs in the Indian subcontinent as well as surrounding countries: Sri Lanka in the east, Iran in the west, and also Pakistan and Nepal. This species is found in freshwater lakes, marshes, and ponds, and has also adapted well to reservoirs, human-made ponds, irrigation canals, and coastal saltwater lagoons. This crocodile likes shallow water no more than 5 m deep, and it avoids fast-flowing rivers. It will sometimes bury itself into the mud to avoid the searing heat in India in the dry season.

Muggers are highly social and their social behavior includes gregarious behavior, communication, territorial activities, and dominance interactions. Between adults and also adults and their young there are many vocalizations. Most of the socializing take place during the seasonal mating activities. Body postures like snout raising and tail thrashing are used by males when establishing territories and trying to gain dominance before courtship and mating. Like other crocodile species, activities include basking, diving, and swimming. In addition, a unique and important activity is burrowing. Burrows are used for thermoregulation during hot and cold periods of the day and at night muggers come out to seek food. During dry seasons, muggers walk many kilometers overland in search of water and prey and they can chase prey for short distances on land. They are adapted better than most other crocodiles to life on land.

Muggers are primarily carnivorous, eating mostly fish, frogs, crustaceans, insects, mammals, birds, and sometimes monkeys and squirrels. They also scavenge on dead animals.

Credit : Animalia 

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Gharials are one of the largest members of the crocodilian family. They look very similar to crocodiles and alligators, but they have a distinctive long, narrow snout, which reduces water resistance and helps them to hunt for fish. Historically, they lived in only four river systems in the world, but have now become extinct in many areas. The gharial is now listed as a Critically Endangered species. Read on to learn about the gharial.

Gharials have a typical crocodilian shape, other than their extremely elongated, narrow snouts. They are covered with smooth, non-overlapping scales. Adults are generally a dark or light-olive color, and youngsters usually have speckling and dark cross-bands on their heads, bodies, and tails. They have partly webbed fingers and toes. Like other crocodilians, they have a very thick, powerful tail, which is flattened on the sides (“laterally compressed”).

The male gharial has a large, hollow swelling at the end of his snout that is known as a “nasal boss.” This only develops when he becomes sexually mature. This swelling, and the males’ greater body-size, makes it easy to distinguish between male and female gharials (i.e. sexual dimorphism), something which is rare among other crocodilians. The function of the nasal boss is not well understood, but it might be a visual sex indicator, or it might be used as a sound resonator.

Gharials generally prefer clear, flowing, freshwater rivers with deep pools and plenty of fish. They also like habitats with sand-banks or san-bars for nesting and basking in the sun.

Gharials are found in small populations in only a few localities in the Northern part of the Indian Subcontinent.

Young gharials eat small fish, frogs, tadpoles, and insects. Adults also feed on larger fish and crustaceans. Gharials do not chew their prey, rather, they swallow it whole.

Credit : Animals.net

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Earth’s largest living crocodilian—and, some say, the animal most likely to eat a human—is the saltwater or estuarine crocodile. Average-size males reach 17 feet and 1,000 pounds, but specimens 23 feet long and weighing 2,200 pounds are not uncommon.

Saltwater crocs, or "salties," as Australians affectionately refer to them, have an enormous range, populating the brackish and freshwater regions of eastern India, Southeast Asia, and northern Australia. They are excellent swimmers and have often been spotted far out at sea.

Classic opportunistic predators, they lurk patiently beneath the surface near the water's edge, waiting for potential prey to stop for a sip of water. They’ll feed on anything they can get their jaws on, including water buffalo, monkeys, wild boar, and even sharks. Without warning, they explode from the water with a thrash of their powerful tails, grasp their victim, and drag it back in, holding it under until the animal drowns.

Salties are considered at low risk for extinction. But saltwater croc hides are valued above all other crocodilians, and illegal hunting, habitat loss, and antipathy toward the species because of its reputation as a man-eater continue to put pressure on the population.

Credit : National Geographic

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The Nile crocodile has a somewhat deserved reputation as a vicious man-eater. The proximity of much of its habitat to people means run-ins are frequent. And its virtually indiscriminate diet means a villager washing clothes by a riverbank might look just as tasty as a migrating wildebeest. Firm numbers are sketchy, but estimates are that up to 200 people may die each year in the jaws of a Nile croc.

Africa's largest crocodilian can reach a maximum size of about 20 feet and can weigh up to 1,650 pounds. Average sizes, though, are more in the range of 16 feet and 500 pounds. They live throughout sub-Saharan Africa, the Nile Basin, and Madagascar in rivers, freshwater marshes, and mangrove swamps.

The diet of the Nile crocodile is mainly fish, but it will attack almost anything unfortunate enough to cross its path, including zebras, small hippos, porcupines, birds, and other crocodiles. It will also scavenge carrion, and can eat up to half its body weight at a feeding.

Hunted close to extinction in the 1940s through the 1960s, local and international protections have helped them rebound in most areas. In some regions, though, pollution, hunting, and habitat loss have severely depleted their numbers.

One unusual characteristic of this fearsome predator is its caring nature as a parent. Where most reptiles lay their eggs and move on, mother and father Nile crocs ferociously guard their nests until the eggs hatch, and they will often roll the eggs gently in their mouths to help hatching babies emerge.

Credit : National Geographic

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The dwarf crocodile is the smallest species of crocodile in the world, growing up to 1.5 metres (4.9 feet) in length. When compared to the largest species, the saltwater crocodile (up to 5.2m/17 feet in length), they really do dwarf in comparison!

Dwarf crocodiles can be found in the mangrove swamps, rainforests and slow moving rivers and streams of West Africa and are mostly active at night when they like to feed on small animals such as fish, insects, lizards, water birds and shrews.

Dwarf crocodiles can lay up to ten eggs at any one time. Good diggers, the females lay their eggs in mounds of soil and vegetation. The female will dutifully guard the eggs until they hatch and will continue to look after the hatchlings once in the water.

The Dwarf crocodile is an African reptile. The area of its distribution stretches from sub-Saharan regions to west-central Africa, from southern Senegal to the Democratic Republic of the Congo, reaching as south as northern Angola. The primary habitat of the Dwarf crocodile is rainforest. The reptile occurs in tropical lowland regions, where the animal inhabits swamps with dense vegetation, slow flowing currents and rivers. In addition, the Dwarf crocodiles are sometimes found in savannah pools.

Credit : Folly Farm 

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Snow leopard is found only in mountain regions of Central and South Asia. Its fur is whitish to grey with black spots on head and neck, with larger rosettes on the back. It has bushy tail and pale green eyes. It is active at dusk and dawn and it hunts wild goats, sheep, hares, rodents and birds. It uses its unique coat to camouflage itself in the snowy landscape.

Few humans have seen snow leopards in real life, but hunting scenes like the one above have been captured on video by researchers who spend countless hours searching the mountains of Central Asia for snow leopards. Researchers think only 3,500 to 7,000 snow leopards exist in the wild, but no one knows for sure.

Snow leopard experts need to gather more information about the secretive cats’ lives to help protect them. To do that, researchers use high-tech tools to spy on the shy animals. They gently trap the wild cats to examine them and put on satellite radio collars to track where the cats roam. Motion-activated digital cameras capture images of snow leopards, exposing many new details about how many there are, how they live, and what threatens their survival.

Even though snow leopards live in some of the most rugged mountain terrain on Earth, people pose the biggest threat to their survival. Poachers can sell a snow leopard’s hide and bones for thousands of dollars. Herders often kill any snow leopard that attacks their livestock. Hunters target ibex, wild sheep, and other animals for food and trophies—removing important snow leopard prey. The more scientists can learn about snow leopards, the better they can protect these rarely seen cats from humans who harm them.

Credit : National Geographic

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When faced with the option of having to either find our way through dense forests or simply take a trail already created, humans are likely to choose the latter. A recent study shows that wolves too are doing exactly that take human-made trails. Is that good or bad news?

Researchers tracked as many as 142 wolves using GPS collars -across British Columbia, Alberta, and Saskatchewan spanning over 5, 00,000 sq km, and discovered something startling. In the northern boreal forests of western Canada, these wolves are often choosing trails created by humans (and "the path of least resistance), which allow them to move faster and farther than before. The perks? Convenient hunting! They now have easier access to their prey, the boreal woodland caribou, and “an iconic species in Canada". While it's great for the wolves, the same cannot be said of their prey. Increasing wolf movement appears to be causing a decrease in the caribou population, already a threatened species. These "caribou are being hunted by wolves at rates they cannot sustain".

These human-made trails were created "to extract resources, creating roads for forestry and seismic lines searching for underground oil and gas deposits". And, "caribou live across large areas, overlapping places where the energy and forestry sectors are actively extracting natural resources" such as oil, gas and timber. Already dealing with habitat loss, the caribou now face another form of threat from the wolves.

Thankfully, it may not be too late to save them. Habitat restoration is suggested to keep a healthy balance between wolf and caribou populations. Though it is expensive and time consuming", "habitat restoration has two main goals: to reduce wolf hunting efficiency by limiting their use of trails and slow their movement when on them and to return the forest to caribou habitat'. As it is with most instances, what is created to ease human life seems to be affecting the natural rhythm of our environment. So, it only seems fair that we set it right.

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The loggerhead turtle is named for its large head, which supports powerful jaw muscles that enable them to feed on hard-shelled prey, such as whelks and conch. Loggerheads are the most abundant species of sea turtle that nests in the United States. Juvenile and adult loggerheads live in U.S. coastal waters, but many adults that nest on U.S. beaches migrate from neighboring nations like the Bahamas, Cuba, and Mexico. 

Loggerhead populations in the United States declined due to bycatch in fishing gear such as trawls, gillnets, and longlines. The use of turtle excluder devices (TEDs) in shrimp trawls, gillnet bans, and other gear modification have reduced sea turtle bycatch in some fisheries, but bycatch in fishing gear remains the biggest threat facing loggerheads. 

Loggerhead turtles have large heads with powerful jaws. The top shell (carapace) is slightly heart-shaped and reddish-brown in adults and sub-adults, while the bottom shell (plastron) is generally a pale yellowish color. The neck and flippers are usually dull brown to reddish brown on top and medium to pale yellow on the sides and bottom. Unlike freshwater turtles and tortoises, sea turtles cannot withdraw their head or flippers into their shells. Hatchlings are mostly dark brown, their flippers have white to white-gray margins, and the  bottom shell is generally yellowish to tan.

Loggerhead turtles, like all sea turtles, are marine reptiles and must come to the surface to breathe air. Adult female sea turtles return to land to lay their eggs in the sand—they are remarkable navigators and usually return to a beach in the general area where they hatched decades earlier.

The life history of loggerhead turtles involves a series of stages of development from hatchling to adult. Hatchlings and juveniles spend the first 7 to 15 years of their lives in the open ocean. Then they migrate to nearshore coastal areas where they will forage and continue to grow for several more years. Adult loggerhead turtles migrate hundreds to thousands of kilometers from their foraging grounds to their nesting beaches. 

Through satellite tracking, researchers have discovered that loggerheads in the Pacific undertake a trans-Pacific migration. Hatchlings from nesting beaches in Japan and Australia migrate across the Pacific to feed off the coast of Baja California, Mexico, Peru and Chile—nearly 8,000 miles! They spend many years (possibly up to 20 years) growing to maturity and then migrate back to the beaches where they hatched in the Western Pacific Ocean to mate and nest and live out the remainder of their lives.

Loggerheads are carnivores, only occasionally consuming plant material. During their open ocean phase, they feed on a wide variety of floating items. Unfortunately, trash and other debris discarded by humans also tends to accumulate in their habitat. Small fragments of plastic are often mistaken for food and eaten by turtles. Juveniles and adults in coastal waters eat mostly bottom dwelling invertebrates such as whelks, other mollusks, horseshoe crabs, and other crabs. Their powerful jaws are designed to crush their prey.

Credit :  NOAA Fisheries 

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Olive ridleys are considered the most abundant sea turtle in the world. They get their name from the coloring of their heart-shaped shell, which starts out gray but becomes olive green once the turtles are adults. They have one to two visible claws on each of their paddle-like flippers. Western Atlantic olive ridleys usually have a darker coloration than eastern Pacific olive ridleys. Adult turtles are relatively small, averaging 2 to 2.5 feet (0.6 to 0.7 meters) in length and weighing 80 to 110 pounds (36 to 49 kilograms). The largest of these animals are observed on the Pacific coast of Mexico.

The olive ridley is found in the tropical regions of the Pacific, Atlantic, and Indian Oceans. In the Pacific, it prefers beaches of Mexico south to Colombia. In the Indian Ocean, its greatest abundance is in eastern India and Sri Lanka. Only a small and declining population of olive ridleys nest in the western Atlantic along the western coast of Africa.

Olive ridleys do not nest along coastal beaches of the United States, but do utilize waters of the southwestern U.S., and sometimes north to the Oregon coast during feeding migration. The olive ridley appears to be more of an open ocean inhabitant, unlike the Kemp’s ridley, which primarily inhabits shallow nearshore coastal waters.

The olive ridley is omnivorous, meaning it feeds on both plants and animals, including algae, lobster, crabs, tunicates, mollusks, shrimp, and fish. Olive ridleys can be found foraging for invertebrates to depths of about 500 feet (150 meters).

Credit : National Wildlife Federation 

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Hawksbill sea turtles inhabit the tropical and sub-tropical waters of all of the world’s major oceans. Hawksbills get their name from their unique beak-like mouth, which resembles that of a hawk and is perfect for finding food sources in hard-to-reach cracks and crevices. They are the only species of sea turtle that can survive on a diet consisting mainly of sponges. Hawksbill turtles play a key role in the function of marine ecosystems.

In many parts of the world, hawksbills face the unique threat of being hunted for their beautiful shell, also known as “tortoise shell”, which is used by craftspeople to create many types of jewelry and trinkets. The historical hunting and killing of hawksbills for their shell nearly drove the species to extinction. Today, the Convention on International Trade of Endangered Species (CITES) forbids the trade of any turtle products on the international market, including hawksbill tortoise shell, but illegal hunting continues to represent a threat to the species in many parts of the world.

Hawksbill turtles have mottled shells consisting of an irregular combination of shades of amber, orange, red, yellow, black and brown. The shells typically have serrated edges, with overlapping scutes.  Their head comes to a tapered point and their lower jaw is V-shaped, giving them a hawk-like appearance. Hawksbills grow up to 2 to 3 feet in shell length and can weigh between 100 and 150 pounds at maturity. Hatchlings are only 2 to 3 inches long and mostly brown in color. Hawksbills have four scales (two pairs) between their eyes and four scutes along the edge of each side of their carapace.

Credit : NOAA Fisheries

Picture Credit : Google

The leatherback sea turtle is the largest turtle in the world. They are the only species of sea turtle that lack scales and a hard shell. They are named for their tough rubbery skin and have existed in their current form since the age of the dinosaurs. Leatherbacks are highly migratory, some swimming over 10,000 miles a year between nesting and foraging grounds. They are also accomplished divers with the deepest recorded dive reaching nearly 4,000 feet—deeper than most marine mammals.

The leatherback turtle has the widest global distribution of any reptile, with nesting mainly on tropical or subtropical beaches. Once prevalent in every ocean except the Arctic and Antarctic, the leatherback population is rapidly declining in many parts of the world. They face threats on both nesting beaches and in the marine environment. The greatest of these threats worldwide are incidental capture in fishing gear (bycatch), hunting of turtles, and collection of eggs for human consumption. The Pacific leatherback turtle populations are most at-risk of extinction. Pacific leatherbacks are one of nine ESA-listed species identified in NOAA’s Species in the Spotlight initiative. Through this initiative, NOAA Fisheries has made it a priority to focus recovery efforts on stabilizing and recovering Pacific leatherback populations in order to prevent their extinction.

NOAA Fisheries and our partners are dedicated to conserving and recovering leatherback turtle populations worldwide. We use a variety of innovative techniques to study, protect, and recover this endangered species. We engage our partners as we develop regulations and recovery plans that foster the conservation and recovery of leatherbacks and their habitats, and we fund research, monitoring, and conservation projects to implement priorities outlined in recovery plans.

Credit : NOAA Fisheries 

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The green sea turtle is the largest hard-shelled sea turtle. They are unique among sea turtles in that they are herbivores, eating mostly seagrasses and algae. This diet is what gives their fat a greenish color (not their shells), which is where their name comes from.

Green turtles are found throughout the world. They nest in over 80 countries and live in the coastal areas of more than 140 countries. Historically, green turtles were exploited for their fat, meat and eggs, causing global population declines. Many countries, including the United States, prohibit the killing of sea turtles and collection of their eggs. However, in some areas, the killing of green turtles for their meat or to supply shells to the wildlife trafficking trade remains a threat to their recovery. Bycatch in commercial and recreational fishing gear, vessel strikes, loss of nesting habitat from coastal development, and climate change are the biggest threats facing green turtles.

NOAA Fisheries and our partners are dedicated to protecting and recovering green turtle populations worldwide. We use a variety of innovative techniques to study, protect, and recover these threatened and endangered populations. We engage our partners as we develop measures and recovery plans that foster the conservation and recovery of green turtles and their habitats. And we fund research, monitoring, and conservation projects to implement priorities outlined in recovery plans.

Credit : NOAA Fisheries 

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