Category Sea/Ocean

WHAT IS A SEA STACK?

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.

Credit: Science Struck

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WHAT IS WEATHERING CAUSED BY SALT CRYSTALS CALLED?

Haloclasty is a type of physical weathering caused by the growth of salt crystals. The process is first started when saline water seeps into cracks and evaporates depositing salt crystals. When the rocks are then heated, the crystals will expand putting pressure on the surrounding rock which will over time splinter the stone into fragments.

Salt crystallization may also take place when solutions decompose rocks (for example, limestone and chalk) to form salt solutions of sodium sulfate or sodium carbonate, from which water evaporates to form their respective salt crystals.

The salts which have proved most effective in disintegrating rocks are sodium sulfate, magnesium sulfate, and calcium chloride. Some of these salts can expand up to three times or more in volume.

It is normally associated with arid climates where strong heating causes strong evaporation and therefore salt crystallization. It is also common along coasts. An example of salt weathering can be seen in the honeycombed stones in sea walls.

Credit: Wikipedia

Picture Credit : Google 

WHY IS OCTOPUS BLOOD BLUE?

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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What are Hurricanes?

A hurricane is a giant, spiralling tropical storm in the Atlantic Ocean that can reach wind speeds of over 257 km per hour and unleash more than nine trillion litres of rain! It begins as thunderstorms that are set off by moist air rising over the warm ocean. If the water is warm enough, the thunderstorms join together, growing bigger as they begin to spiral across the ocean. As the hurricane grows, it spins faster and tighter around its centre, or ‘eye’, which remains a very calm area of low pressure. A hurricane can be as much as 800 km across and can take l8 hours to pass over. In the northern Indian Ocean hurricanes are known as cyclones and in the western Pacific Ocean, as typhoons.

Hurricanes are large, swirling storms. They produce winds of 119 kilometers per hour (74 mph) or higher. That’s faster than a cheetah, the fastest animal on land. Winds from a hurricane can damage buildings and trees.

Hurricanes form over warm ocean waters. Sometimes they strike land. When a hurricane reaches land, it pushes a wall of ocean water ashore. This wall of water is called a storm surge. Heavy rain and storm surge from a hurricane can cause flooding.

Once a hurricane forms, weather forecasters predict its path. They also predict how strong it will get. This information helps people get ready for the storm.

There are five types, or categories, of hurricanes. The scale of categories is called the Saffir-Simpson Hurricane Scale. The categories are based on wind speed.

  • Category 1: Winds 119-153 km/hr (74-95 mph) – faster than a cheetah
  • Category 2: Winds 154-177 km/hr (96-110 mph) – as fast or faster than a baseball pitcher’s fastball
  • Category 3: Winds 178-208 km/hr (111-129 mph) – similar, or close, to the serving speed of many professional tennis players
  • Category 4: Winds 209-251 km/hr (130-156 mph) – faster than the world’s fastest rollercoaster
  • Category 5: Winds more than 252 km/hr (157 mph) – similar, or close, to the speed of some high-speed trains

Credit: NASA

Picture credit: NASA

IS THERE ANY UNDERWATER VOLCANO IN THE ISLAND OF MAYOTTE?

In 2018, seismometers around the world detected mysterious rumbles emanating from a usually quiet area in the Indian Ocean between Comoros and Madagascar. At the time, researchers were astonished to find a 2,690-foot-tall underwater volcano, which is about 1.5 times the height of the One World Trade Center in New York.

The volcano was formed after the largest underwater eruption ever detected and now, scientists suspect that the volcano draws its lava from the deepest volcanic magma reservoir known to researchers.

Scientists first took notice of volcanic activity about 31 miles east of the French island of Mayotte in 2018 when seismic hums, or low-frequency earthquakes, were detected by seismometers all over the globe. However, the huge underwater volcano shocked scientists because only two seismic events had been recorded near Mayotte since 1972. Before that, a layer of 4,000-year-old pumice in a lagoon nearby is the only additional evidence of an eruption ever found. After researchers noticed that the island was moving eastward about 7.8 inches a year, they installed ocean-bottom seismometers and GPS systems to track the island’s fascinating geological activity. To understand the origin of the tremors that began in 2018, the study’s lead author Nathalie Feuillet, a marine geoscientist at the French National Center for Scientific Research, along with her team embarked on a mission—dubbed MAYOBS1—aboard the French research vessel Marion Dufrense in 2019.

Credit : Smith sonian magazine

Picture Credit : Google 

WHAT ARE THE FUN FACTS ABOUT DUGONG?

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.

Credit :  Kidadl

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