My Science School

Saltwater crocodiles enjoy "catching a wave" and can travel hundreds of kilometres by surfing on ocean currents. This current riding behaviour allows for the conservation of energy. Estuarine or saltwater crocodiles (Crocodylus porosus), found in Southern Asia and Australia, are the world's largest reptiles and can grow up to 5.5 metres in length.

Working at the remote Kennedy River in northeastern Australia, the team of scientists — which included the late Steve Irwin, "The Crocodile Hunter" — tagged 27 adult seawater crocodiles with sonar transmitters, employing 20 underwater receivers deployed along a 39-mile-long stretch of the river (63 km) to track the reptiles' every move for more than 12 months. They found both male and female adult crocodiles undertook long-distance journeys, regularly traveling more than 30 miles (48 km) from their home area to the river mouth and beyond into open sea.

The scientists also discovered the "salties" always began long-distance travel within an hour of the tide changing, allowing them to go with the flow. They halted their journeys by hauling out onto the river bank or diving to the river bottom when the currents turned against them.

The researchers originally were just aiming to investigate the territorial habits of the crocodiles and how they divvied up land among themselves.

Credit : Live Science 

Picture Credit : Google

Baby turtles make sounds to communicate with each other while still in the egg, to help synchronize when they hatch. Being able to coordinate hatching times is an important survival technique. If they all hatch together, there is a better chance that more of them will make it across the beach and into the water.

Researchers from Brazil, Mexico and the US got together to study the nests of 12 leatherback sea turtle nests in Oaxaca, Mexico. Starting on day 51, the point at which the babies's ears should be developed enough to hear sounds, they monitored the nests for any signs of noise. They immediately began detecting sounds, recording more than 300 different noises in total. They classified the sounds into four categories, including chirps, grunts and "complex hybrid tones," or sounds composed of two parts that they classified as pulse characteristics and harmonic frequency bands. 

That latter sound - the most complex of the bunch - was only recorded in nests that contained just eggs, rather than eggs and hatchlings (most had begun hatching by day 55). The baby turtles, the researchers believe, may be coordinating their hatching timing by emitting the sounds. This phenomenon has been observed in other animals ranging from birds to crocodiles, likely as a survival mechanism. In the case of the turtles, hatching en masse brings a certain strength in numbers. While some babies will be picked off by predators, a bird can only eat so many sea turtles at a time, meaning at least a few will make it to the sea. 

This finding, the authors point out, means that light pollution might not be the only anthropogenic nuisance threatening baby sea turtle survival. Noise pollution could be affecting them, too. 

Credit : Smithsonian 

Picture Credit : Google

Shark teeth have naturally built-in toothpaste! The surface of shark teeth contains 100 per cent fluoride, the active ingredient in most toothpastes. They also have the handy ability to replace their teeth several times during their lives, because their teeth sometimes end up stuck in prey or are otherwise forced out.

According to the study, their teeth are perfectly designed for such tasks, never suffering from cavities.

While shark teeth contain the mineral fluoroapatite (fluorinated calcium phosphate), the teeth of humans and other mammals contain hydroxyapatite, which is an inorganic constituent also found in bone, explained co-author Matthias Epple.

“In order to make teeth more acid resistant, toothpaste often contains fluoride,” Discovery News quoted Epple, a professor of inorganic chemistry at the University of Duisburg-Essen, as saying.

“In the surface of human teeth after brushing, a small amount -- much less than 1 percent -- of hydroxide is exchanged by fluoride.

“In contrast, (the surface of) shark teeth contains 100 percent fluoride. In principle, sharks should not suffer from caries. As they live in water and as they change their teeth regularly, dental protection should not be a problem for sharks,” he said.

Credit : Hindustan Times 

Picture Credit : Google

A species of "immortal" jellyfish can age backward. The Turritopsis dohrnii jelly fish can revert back to its juvenile stage from its adult stage, doing it several times over, making it the only known officially immortal creature. When starvation, physical damage or other crises arise, instead of sure death, Turritopsis turns itself into a bloblike cyst, which then develops into a polyp colony (the first stage in jellyfish life) which can spawn hundreds of genetically identical jellyfish - near perfect copies of the original adult.

Fully grown, Turritopsis dohrnii is only about 4.5 mm (0.18 inches) across, smaller than a pinky nail. A bright-red stomach is visible in the middle of its transparent bell, and the edges are lined with up to 90 white tentacles. These tiny, transparent creatures have an extraordinary survival skill, though. In response to physical damage or even starvation, they take a leap back in their development process, transforming back into a polyp. In a process that looks remarkably like immortality, the born-again polyp colony eventually buds and releases medusae that are genetically identical to the injured adult. In fact, since this phenomenon was first observed in the 1990s, the species has come to be called “the immortal jellyfish.”

The cellular mechanism behind it—a rare process known as transdifferentiation—is of particular interest to scientists for its potential applications in medicine. By undergoing transdifferentiation, an adult cell, one that is specialized for a particular tissue, can become an entirely different type of specialized cell. It’s an efficient way of cell recycling and an important area of study in stem cell research that could help scientists replace cells that have been damaged by disease.

As for Turritopsis dohrnii, this jelly is not only an extraordinary survivor. It’s also an increasingly aggressive invader. Marine species have long been known to hitch rides around the world in the ballasts of ships. Researchers have recently identified the immortal jellyfish as an “excellent hitchhiker,” particularly well-suited to surviving long trips on cargo ships.

Credit : AMNH

Picture Credit : Google