My Science School

When the movement of waves deposits gravel and sand in a manner that prevents access to a bay, it builds up a baymouth bar. The existence of the bar creates a shallow lake known as a lagoon that is separated from the sea by a beach.

A baymouth bar is a depositional feature as a result of longshore drift. It is a spit that completely closes access to a bay, thus sealing it off from the main body of water. These bars usually consist of accumulated gravel and sand carried by the current of longshore drift and deposited at a less turbulent part of the current. Thus, they most commonly occur across artificial bay and river entrances due to the loss of kinetic energy in the current after wave refraction.

In most cases, a Sand Bypass System is built to prevent these bars forming across the entrance of man-made seaway's, eliminating the danger posed to commercial and recreational boat owners passing through.

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Man-made, shore protection measures to reduce erosion. Constructed of wood or stone, groynes control the movement of water rushing onto the beach and prevent sand from being swept away by the waves. A number of groynes usually run perpendicular to the shore and extend up to the sea.

A groyne is a rigid hydraulic structure built perpendicularly from an ocean shore (in coastal engineering) or a river bank, interrupting water flow and limiting the movement of sediment. It is usually made out of wood, concrete, or stone. In the ocean, groynes create beaches, prevent beach erosion caused by longshore drift where this is the dominant process and facilitate beach nourishment. There is also often cross-shore movement which if longer than the groyne will limit its effectiveness. In a river, groynes slow down the process of erosion and prevent ice-jamming, which in turn aids navigation.

Groynes run generally perpendicular to the shore, extending from the upper foreshore or beach into the water. All of a groyne may be underwater, in which case it is a submerged groyne. They are often used in tandem with seawalls and other coastal engineering features. Groynes, however, may cause a shoreline to be perceived as unnatural. Groynes are generally straight but could be of various plan view shapes, permeable or impermeable, built from various materials such as wood, sand, stone rubble, or gabion, etc.

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The Kiama Blowhole is a blowhole in the town of Kiama, New South Wales, Australia. The name ‘Kiama’ has long been translated as “where the sea makes a noise”. It is one of the town's major tourist attractions. Under certain sea conditions, the blowhole can spray 50 litres of water up to 25 metres (82 ft) in the air, in quantities that thoroughly drench any bystanders. There is a second, less famous blowhole in Kiama, commonly referred to as the "Little Blowhole" by locals. It is much smaller than the other (called the "Big Blowhole"), but due to its narrow shape, it is more reliable than the Big Blowhole, and in the right conditions can be equally spectacular.

The blowhole attracts 900,000 tourists a year. Kiama Blowhole is just a few metres beyond the coastline. The "little blowhole" is located at the Little Blowhole Reserve, Tingira Crescent, Kiama, 2km south of the main blowhole.

The blowhole was formed from basalt lava flows approximately 260 million years ago and was first discovered by local Aboriginals who named it 'Khanterinte'. The blowhole was first written about by George Bass on 6 December 1797. Bass had captained a crew of six and set out on an open whaleboat to explore the south coast of Australia. He noticed the blowhole after anchoring his boat in a sheltered bay.

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Tombolo, one or more sandbars or spits that connect an island to the mainland. A single tombolo may connect a tied island to the mainland, as at Marblehead, Mass. A double tombolo encloses a lagoon that eventually fills with sediment; fine examples of these occur off the coast of Italy. The shallower waters that occur between an island and the mainland are the loci of such features because sandbars form there.

Adam’s Bridge, which connected Sri Lanka (Ceylon) with India across the 33-mile (53-kilometre) wide Palk Strait, was formerly the world’s largest tombolo. It was destroyed several thousand years ago by a slight change in mean sea level, and only a chain of sandbanks that seriously hinder navigation exists there today.

Credit: Britannica

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The Twelve Apostles Marine National Park is a protected marine national park located on the south-west coast of Victoria, Australia. The 7,500-hectare (19,000-acre) marine park is situated near Port Campbell and is named after the scenic The Twelve Apostles rock stacks, and contains the wreck of the clipper Loch Ard, wrecked on Mutton Bird Island in 1878. The marine park borders Port Campbell and Great Otway National Parks.

The limestone unit that forms The Twelve Apostles is referred to as the Port Campbell Limestone, which was deposited in the Mid-Late Miocene, around 15 to 5 million years ago.

The Twelve Apostles were formed by erosion. The harsh and extreme weather conditions from the Southern Ocean gradually erode the soft limestone to form caves in the cliffs, which then become arches that eventually collapse, leaving rock stacks up to 50 m (160 ft) high. The stacks are susceptible to further erosion from waves. In July 2005, a 50-metre-tall (160 ft) stack collapsed, leaving seven standing at the Twelve Apostles viewpoint. Due to wave action eroding the cliffs, existing headlands are expected to become new limestone stacks in the future.

The stacks were originally known as the Pinnacles, and the Sow and Pigs (or Sow and Piglets, with Mutton bird Island being the Sow and the smaller rock stacks being the Piglets), as well as the Twelve Apostles. The formation's name was made official as the Twelve Apostles, despite only ever having had eight stacks.

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A sea stack is a vertical column of rock near a coast. This column is the remains of limestone cliffs that have been battered by the sea from both sides. At first, the waves carve out deep caves in the cliffs, which then gradually collapse, leaving behind the steep stack of rocks.

By definition, a sea stack is a naturally occurring pillar made up of stacked rocks, that projects up towards the sky. It is usually found surrounded by water, especially during high tide, isolated and separate from the mainland mass at a small distance away. During low tide, the water recedes far enough so that some sea stacks become accessible via the beach.

Standing at the foot of a sea stack, looking up at that magnificent, yet oddly placed rock formation, one is likely to wonder how exactly did it get there? While the possibility of a divine hand at work might seem alluring, the truth is actually a little more interesting. These grand structures of rocks are actually created by the erosive powers of waves and winds.

Sea stacks are formed from headlands. A headland is a coastal land-form that is quite high, and has a sheer drop that extends out into the sea or ocean. Parts of the headland that jut out into the water slowly get eroded over time by the mechanical energy of winds and waves. Essentially, the softer and weaker part of the rocks get eroded and break away, leaving behind the harder and stronger rock.

The formation process usually begins when water starts smashing against the portion of the headland rock that is jutting out, causing it to slowly erode. Coastal winds too assist in this process. Both, waves and winds chisel away at the rocks continuously for many years, until finally, a cave is formed.

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Potable water for all still remains a dream as there are several people without easy access to safe drinking water. MIT researchers have come up with a portable desalination unit that can remove particles and salts even from seawater to generate drinking water. The results of their research has been published in Environmental Science and Technology.

Push of a button

The suitcase-sized device that they have developed weighs less than 10 kg. requires less power to operate than a cell phone charger and can even be driven by a small solar panel. Generating water that exceeds World Health Organisation quality standards, the technology is packed in a user-friendly way and runs with the push of a button.

Most commercially available portable desalination units require high pressure pumps to push water through filters. As it is impossible to miniaturise filters without compromising on the energy efficiency, the researchers took to alternative methods.

ICP and electro-dialysis

The researchers employed a technique called iron concentration polarisation (ICP). The ICP process applies an electric field to membranes placed above and below a channel of water. ICP uses less energy than other techniques and the process removes both dissolved and suspended solids.

ICP, however, isn't foolproof and does not always remove all the salts. To counter this, a second process of electro-dialysis was also incorporated in the device. With the help of machine learning, the ideal combination of ICP and electro-dialysis modules were found out. These modules were then shrunk and stacked to improve their energy efficiency and also to fit them within a portable device.

Following successful lab experiments where drinking water was produced from water sources with different salinity and turbidity levels, the device was then field tested at Boston's Carson Beach. The device was able to fill a plastic drinking cup with drinking water in about half an hour.

Improve production rate

While the water produced thus is of good quality, the current prototype generates only 0.3 litres of drinking water per hour and consumes 20 watts of power per litre. Enhancing the energy efficiency and improving the production rate are foremost in the minds of those who wish to commercialise the technology.

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The octopus is a surprisingly complex creature and, quite possibly, the world's original "blue blood." Its 500 million neurons are distributed throughout its head and body, compared to the 100 billion neurons in our brains. The octopus's brain power isn't easily apparent at first glance, but it's proven itself capable of planning, reasoning and -- predicting sporting matchups. On the planning front, researchers have discovered that octopuses in Indonesia will gather coconut shell halves in preparation for stormy weather, then take shelter by going inside the two pieces of shell and holding it shut.

So what makes these smart sea creatures so adaptable? The ability is literally in their blood. The same pigment that gives the octopus blood its blue color, hemocyanin, is responsible for keeping the species alive at extreme temperatures. Hemocyanin is a blood-borne protein containing copper atoms that bind to an equal number of oxygen atoms. It's part of the blood plasma in invertebrates.

Blue-hued hemocyanin binds to oxygen in the blood and transports it throughout the octopus's body to supply tissues, a critical factor in its survival. Octopuses have three hearts and need more oxygen than most other invertebrates, so the hemocyanin allows octopuses to get a steady oxygen supply, even when it isn't readily available in their environment. It also ensures that they survive in temperatures that would be deadly for many creatures, ranging from temperatures as low as 28 degrees Fahrenheit (negative 1.8 degrees Celsius) to superheated temperatures near the ocean's thermal vents.

Researchers suspect the "blue blood" adaptation is the result of the octopus's inability to migrate away from challenging environmental conditions.

Credit : How stuff works

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A Dugong (family: Dugongidae) is the only herbivorous marine mammal found in deep waters. Dugong is a mammal that is closely related to elephants. It is a huge bulbous animal who is usually grey brown in color. Like whales, they have flattened fluked tail, a distinctive head shape, paddle like flippers but do not have any dorsal fin. The dugong is a marine mammal that is the only herbivore found in the deep waters that eats seagrass. Dugongs, even though they resemble a manatee, do not belong to the family of manatees. They weigh less than manatees and have different physical characteristics. Their rarity and the decreasing population are a great threat to their extinction. Issues like degradation of sea beds and illegal fishing traps are a major threat to the Dugong population.

There are very few dugongs that live in shallow waters of Australia, the Indian, and Pacific Ocean. Dugongs are listed as creatures that are vulnerable to extinction by the IUCN Red List. The numbers of these beautiful sea creatures are decreasing day by day due to the loss of seagrass beds and pollution of water which disrupts their habitation. Illegal fishing and fishing of dugongs for consumption and trade also is causing their population to decrease. They cannot live in freshwater and can tolerate marine water. Dugongs communicate by emitting sounds which are similar to chirps, whistles, barks that travel through water. They also communicate through sounds that echo underwater. They are also found in oceans around United States.

A dugong is a marine mammal that is native to the Great Barrier reef, world’s largest coral reef in the continent of Australia. The coastal shallow water around Australia were home to more than 85,000 animals but dugong populations are constantly decreasing across the world and they are highly endangered. The dugong species is hunted to extinction as well as traded to different countries illegally. Dugongs mostly live a sedentary lifestyle and migrate for miles in search of seagrass. Some dugongs prefer living in pairs, while sometimes, a herd of 7-10 Dugongs can be seen habituated. The herd or a group of dugong is called a nutcluster.

Dugongs have a lifespan of 70 years and give birth to only one calf during reproduction. They spend most of their time nursing and tending to their offspring. Low litter count and elongated weaning periods are also the reason why the gugong population is depleting. Young dugong calves are easy prey for crocodiles and sharks, which again contributes to population decrease.

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The blue-ringed octopus may look cute and harmless at the first glance. But take care; it is an extremely poisonous animal!

These small octopuses are common in coral reefs and tide pools of the Pacific and Indian Oceans. They usually stay hidden in crevices, shells or marine debris, their tan-coloured body blending in with the surroundings. But the ‘true colour’ of this shy little thing comes out when threatened by somebody. Bright blue rings appear all over its body as a warning signal, which have given it the name.

If a human is bitten by the blue-ringed octopus it can cause respiratory distress and paralysis and other symptoms too, like nausea, blindness and heart failure.

The venom is not just to fight the enemies, it helps in feeding too. These octopuses usually hunt small crabs and shrimp, but will also eat molluscs and small fish. The octopus delivers the paralyzing venom into the prey. The venom is produced by its saliva, which also contains digestive enzymes. So the flesh of the prey is partially digested before the octopus sucks it out. The blue-ringed octopus is not hurt by its own venom.

The Mediterranean Sea holds a wonder that beats all – something that never dies! It is a jellyfish whose scientific name is Turritopsis dohrnii.

Jellyfish start their lives as larvae, which attach themselves to a suitable place like a rock. Then they are transformed into polyps that have a small body with tentacles. These polyps then clone themselves to form others and create a colony, or a medusa, which is the jellyfish.

When this jellyfish dies, or is physically damaged, the decaying cells form new polyps, and later return to their jellyfish state. This way they could live forever under the right conditions! However, they don’t actually achieve immortality because these tiny wonders are eaten by fish or other animals, or die by other means.

Although the jellyfish has ‘fish’ in its name, it is not fish. It is not made of jelly either. Unlike a fish, it is an animal without a backbone found in oceans and seas around the world. The name jellyfish derives from the jelly-like bodies of these animals. Jellyfish are found in oceans and seas all over the world, in the deepest as well as in shallow water.

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Meet someone whose body tells his own life’s story that runs into centuries! The ocean quahog, a bivalve mollusc that can live more than 500 years, is the longest-lived solitary animal.

The shell of an ocean quahog is a treasure-house of information for scientists. Its shell grows periodically throughout life and the growth patterns visible on the shell function as a calendar. They help not only to tell the age of the animal, but also to know more about the marine environment in the past. For example, scientists would be able to tell from the shell of a quahog, how warm the seas were two centuries ago! The quahogs are the only surviving species of a family of similar claims that had lived during the Dinosaur era!

The ocean quahog (Arctica is landica) lives in the North Atlantic Ocean, buried in sandy sea beds. It feeds on the organic matter it gets by filtering water using its siphon. Interestingly, their feeding activity seems to depend on how much light is available! Thus, in the northern-most regions where they are found, they mostly feed during eight months of the year. During the remaining months, they feed for only a few days.

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The newly hatched, or neonate, ghost shark was found at a depth of 1200m off the east coast of New Zealand's South Island. The rare discovery of a juvenile ghost shark off New Zealand's South Island coast will help researchers better understand the biology and ecology of this mysterious deep water fish.

Ghost sharks or chimaeras are one of the most elusive fish species in the world. They have existed for hundreds of millions of years, but not much is known about them because they usually reside at depths of up to 2,000 metres. The neonate or hatchling was found at a depth of 1,200 metres.

Ghost sharks, also known as ratfish, spook fish or rabbitfish, are not actual sharks but are closely related to sharks and rays. They are cartilaginous, meaning their bodies have stiff armour-like plates and bone-like cartilage. Adult ghost sharks have venomous spines in front of their dorsal fins. Embryos grow inside their egg capsules on the sea floor and feed off the capsules until ready to hatch (between 6 to 12 months).

Critical missing details about the species' life cycle makes monitoring chimaera populations difficult. Sixteen per cent of all ghost shark species are threatened or near threatened.

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Beluga whales are white whales that live in the Arctic. They attract a lot of attention to themselves because of their unique color and the lack of a dorsal fin. Unfortunately, they are kept in captivity more than any other whale or dolphin species. Due to the irresponsible behavior of humans they are now on the edge of extinction. Belugas are pretty and friendly white whales, and their color helps them to stay alive and protects them from danger. There are many interesting facts about the Belugas that you should know and share with your kids.

Belugas are toothed whales, but they never chew their food. They swallow their prey. Another reason why the Beluga Whale is an endangered species is the fact that they have babies only once in three years. The female Beluga always gives birth to one calf and nurses it until it’s two years of age. The period between conception and birth for Beluga whales is 15 months. So, all in all, a female Beluga can give birth to only one new offspring every three-and-a-half years. The word Beluga comes from the Russian word for white. Although, they are born dark-grey, and it takes eight years for them to turn completely white. Amazing, right? Beluga whales can swim backwards. Beluga whales, just like dolphins, have been known to save people’s’ lives by pushing them to the surface when they are drowning. A captive Beluga saved a free diver’s life in 2009 while she was competing. This fact only confirms how good animals are to us even after all the cruelty they suffer. The Belugas are threatened mostly by being captured for captivity, hunting, climate change, oil and gas development, and industrial pollution. The wild predators that hunt them are Orcas and polar bears. Beluga whales are also known as the canaries of the ocean because of their incredible capability to produce different sounds. Scientists recorded eleven types of sounds that Belugas use to communicate with each other, to identify objects or calculate distance. They have a bulbous structure in their forehead that serves as an echo box where all the sounds come from. High-pitched whistles, clicks, mews, bleats, chirps, and bell-like tones are some of the sounds recognized by scientists. The Beluga’s neck is incredibly flexible and can move up and down and left and right. Such neck flexibility helps the whale to spot their prey easily. Beluga whales living in captivity have been recorded mimicking the human voice. It’s quite amazing to hear them imitating the human voice, but on the other hand, that means they spend so much time surrounded by people in an environment that is not their natural habitat. Beluga whales are highly social creatures that like to communicate with each other and with other species as well. They live in groups called pods, and they travel together everywhere. To spot them in real life, you must visit the Arctic Ocean coastal waters where they spend most of their time. Belugas can live 70 to 80 years, though in captivity they only reach a half of that age. Beluga whales can dive up to 25 minutes non-stop, and reach depths of 2624 feet. The beluga can change the shape of its bulbous forehead, called a “melon”, by blowing air around its sinuses.

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No. The water itself does not travel but only moves up and down -it is energy from wind that is transferred in the form of a wave. The energy is transferred through the water in a circular motion. While waves move like a relay team transferring energy, the water goes round like a roller on a conveyor belt.

The ocean is never still. Whether observing from the beach or a boat, we expect to see waves on the horizon. Waves are created by energy passing through water, causing it to move in a circular motion. However, water does not actually travel in waves. Waves transmit energy, not water, across the ocean and if not obstructed by anything, they have the potential to travel across an entire ocean basin.

Waves are most commonly caused by wind. Wind-driven waves, or surface waves, are created by the friction between wind and surface water. As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest. These types of waves are found globally across the open ocean and along the coast.

Credit: National Ocean Service

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