Category Sea/Ocean

How to look after goldfish?

Goldfish make extremely popular pets. They are not difficult to look after providing you follow a few simple rules.

The first serious threat to a goldfish is when it is taken home from the pet shop. It should be swimming around in quite a lot of water and you should not take it in one of those small plastic bags. If you must use a plastic bag take the goldfish out of it as soon as possible or it may suffocate.

A second danger to goldfish is the tank it swims in. Tap-water contains chlorine which is poisonous to goldfish. This water is also too cold and might kill the pet.

A third danger is feeding which is all too often wrong for goldfish. These fish do not require much food, but what they do eat must be carefully chosen. Never give goldfish breadcrumbs: use the special food sold in shops but be careful to give it only in small quantities. Occasionally you can give goldfish a small amount of finely minced raw meat or the crushed yolks of hard-boiled eggs.

The larger the tank the happier the fish will be. The ideal tank is the aquarium but a large bowl will serve. Do not forget that even a goldfish can become bored and pine away living alone, so you should give it a companion, either male or female. Goldfish were originally natives of eastern Asia but were later introduced into China, Japan, Europe and the United States. They have been known to live for twenty-five years in captivity, but the average life span is usually much shorter.


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How sea-fishing carried out?

Fishing is one of the oldest activities known to man. Early man who lived on houses erected on poles above the water of lakes, soon learned how to catch the silent creatures that swam around underneath the surrounding waters. The fishing methods of those primitive peoples did not differ much from the lines, nets and hooks of today.

The implements used in fishing can be quite complicated, such as the lobster pots that are sunk, laden with bait, to the sea-bed and the nets which are rigged up by groups of people working together. When these nets are dragged along the water they are known as trawls.

Other types of nets are placed in the water to form a ring which is then gradually closed round the fish and lifted out of the water. This method is known as purse seining. In other netting systems fishermen simply block the fish’s means of escape and force them to swim into a special area where they are caught.


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What happens when the ocean becomes acidic?

Did you know the oceans absorb 30% of the CO2 emitted on Earth? At the outset, this might seem like a good thing because it means less carbon dioxide in the air and therefore reduction in global warming. But in the past decades, scientists have realised this comes at the cost of changing the ocean’s chemistry.

When carbon dioxide dissolves in seawater, it forms carbonic acid. When emission increases, a lot of CO2 dissolves in the ocean. Incidentally, the rise in CO2 emission is primarily attributed to human activities. The more the CO2, the more acidic the water gets. Subsequently, the pH level of water goes down. (pH is a measure of how acidic or basic water is.) This process is known as ocean acidification. Ocean acidification has the potential to damage the ocean chemistry. Even a small change in the acidity of seawater can have harmful effects on marine life, impacting chemical communication, reproduction, and growth.

Impact on shelled creatures

Ocean acidification affects ocean species in varying degrees. Creatures such as mussels, clams, urchins, starfish and corals are the worst affected. They make their shells and skeletons by combining calcium and carbonate from seawater. As acidification changes the chemistry of the ocean, these organisms struggle to build their shells and skeletons. Even if they are able to build skeletons in more acidic water, they may have to expend more energy which might otherwise be needed for activities such as reproduction. Further, scientists have found that ocean acidification causes shells of some species to dissolve and slows moulting in crabs and lobsters.

Acidification may also limit coral growth by corroding its skeletons. When reef-building corals are affected, a host of marine life that call the reef their home will also be affected.

Impact on fish

A small change in pH can make a huge difference to survival. In humans, a drop in blood pH level of just 0.2-0.3 can cause seizures, coma, and even death. Similarly, fishes are sensitive to pH. If their blood pH drops, they will have to burn extra energy to get rid of the excess acid in their blood through their gills, kidneys and intestines. This will reduce their ability to carry out other tasks such as hunting, escaping predators and reproducing.

Studies have shown that acidification changes the way sounds get transmitted through the water, making the underwater environment noisier.


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What is special about salmon?

Salmon comprises many species of fish. They are unique in that they live both in freshwater and salt water, and for this characteristic they are called “anadromous” Let’s find out more about how this happens.

Found in the Atlantic and Pacific oceans, salmon begin their life in freshwater. For the first few months (sometimes even a few years, depending on the species). The salmon live in freshwater, usually a river. And then they move to the ocean. Again, after living there for a while, when it’s time for them to spawn (lay eggs), they head back as adults to the same river they were born in. Soon after spawning, adults from some species die, and some repeat the cycle. These journeys are said to cover hundreds of miles in a salmon’s lifetime. According to research, salmon have an acute sense of smell, which is what helps them back to their birth place, though much time passes in between. Some have said it’s the Earth’s magnetic field that guides them.

But what’s more fascinating is how their bodies adapt to two different habitats.

Usually fish can die if they switch between salt and freshwater – when salt water fish get into freshwater. Their cells can burst and when freshwater fish enter salt water, their cells can shrivel. However, a complex adaptation mechanism involving body fluids comes into play to help the salmon survive. It happens at the intertidal zone (such as a seashore) before the young salmon enters the ocean. It gets used to the salty water by gradually drinking a lot of it, expelling excess salt and very little urine. These work in reverse when the adult returns to its freshwater home – it hardly drinks freshwater and has no need to expel salt. A study from 2015 made a revelation about another factor that helps the young salmon – light. Increased light during spring increased the production of a special enzyme which “stimulates the fish to prepare itself before it wanders out into salt water’.


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What is group of barracudas called?

A group of barracudas is called a battery. Barracudas are ferocious, opportunistic predators, relying on surprise and short bursts of speed, up to 43 km/h, to overtake their prey.

Barracuda are snake-like in appearance, with prominent, sharp-edged, fang-like teeth, much like piranha, all of different sizes, set in sockets of their large jaws. They have large, pointed heads with an underbite in many species. Their gill covers have no spines and are covered with small scales. Their two dorsal fins are widely separated, with the anterior fin having five spines, and the posterior fin having one spine and 9 soft rays. The posterior dorsal fin is similar in size to the anal fin and is situated above it. The lateral line is prominent and extends straight from head to tail. The spinous dorsal fin is placed above the pelvic fins and is normally retracted in a groove. The caudal fin is moderately forked with its posterior edged double-curved and is set at the end of a stout peduncle. The pectoral fins are placed low on the sides. Its swim bladder is large. Speedy and dynamic, they are slim, with small scales. Barracudas also have two well-separated dorsal fins, a protruding lower jaw, and a large mouth with many large, sharp teeth.


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Why don’t sharks just swim up to whales and start eating them?

Sharks do sometimes prey on whales, but adult whales are massive beasts that can and will kill sharks if they come too close. Calves are sometimes attacked, lone mothers with a calf are preyed upon, but whales often live in pods that defend one another. Even peaceful filter-feeder whales still pack a punch with their tails, whales are social and will defend one another and their sonar (okay, okay, echolocation) gives them immense advantage over sharks.

Fish are deaf or nearly deaf. The shark doesn’t even know the whale has a lock on it and is coming down, hard. The shark will smell the whale but by the time it can see the whale coming it will be too late. The whale can accurately locate the shark from kilometers away and act accordingly.


Credit : Quora

Picture Credit : Google



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