Tag: fish

White Sand is Mostly Parrot Fish Poop

By Anupum Pant

Walking on the sparkling white sand on a sunny beach in Hawaii, sounds wonderful, right? Who’d even think, the white sand on Hawaii beaches, which people love walking on, is actually something that is excreted by a certain kind of fish called the Parrot fish…at least most of it – about 70% of it is poop.

Now, I suppose people walking on the beach must be all grossed out. But they shouldn’t be. It isn’t too bad after all. The sand (poop) doesn’t even smell like anything bad. It looks and feels completely fine. There’s actually no reason to be grossed out.

This is how it works…

The Parrot fish spends most of its time eating sea weed and polyps which grows on coral most of the time. When it tries to puck it off, thanks to the protruded mouth of a parrot fish, it scoops off a part of coral too. The coral and sea weed mixes and gets crushed in its throat.

The sea weed and polyps eventually get digested, while the crushed coral comes out as it is. As a result, it poops out the undigested  crushed coral.

Interestingly, in the process of taking off a chunk of coral and munching it, the parrot fish does two good things.

Firstly, it helps the coral in removing all the parasites and other things growing on it. The fish is considered to be a natural cleaner of corals. Had there been no parrot fish, corals would have died.

Secondly, the parrot fish does a great service to its own beak in this process. As a result, the beaks don’t grow too much.

The parrot fish eats a lot, and each one of them can produce about 100 kg of “sand” every year. It has been confirmed by scientists that about 70% of the sand that is present on all the tropical beaches has come out of the back side of a parrot fish at some point of time.

This is what a parrot fish looks like and this is how it poops out sand…

Bonus fact: Our planet is old and fresh water is less. So, it’s valid to say that all the water molecules that are there now have passed through something really bad, and there’s a high chance that all of it has passed someone’s urinary tract at some point.

Killer Whale’s Ingenious Trick To Kill Sharks

By Anupum Pant

Background

Although mosquitoes are much much deadlier, Great White Sharks no doubt are dangerous animals too. It seems as if there’s nothing this big fish fears. But even this deadly hunter gets hunted.

On the other hand, Orca or the Killer whale is a relatively cuter animal. Remember Free Willy? But to me, these seemingly cute animals are in fact shrewd hunters who like to torture their prey before eating it. They’ve learnt well the tricks of the trade. I feel they are a lot like crows. That is to say, they are extremely intelligent and learn by observing.

For instance, to make seals sitting on ice pieces fall down, the killer whales know a good trick. They make waves and make the ice sheet wobble. As a result, seals fall down. Similarly, by sneaking up, making bubbles to trap fish and by using other such methods, these genius hunters make sure they get their prey.

Also, like Daniel Kish, they use echolocation. But Orcas use it to locate the prey. Still, their intelligence doesn’t always work.

Orcas kill sharks and they know a really efficient trick to do it successfully. They flip the sharks upside down. Here’s how they exactly manage to have “Shark sushi for lunch”.

Tonic Immobility + Ram Ventilation

To kill sharks they employ this very ingenious trick. They cash in on Tonic Immobility. Ironically, Tonic immobility is a defence mechanism some sharks use. Tonic immobility is something that a number of animals use for different purposes. Mostly they do it for defence by faking death.

During this state, their breathing becomes very relaxed and they might look as it they are dead. For instance, lobsters become immobile when they are stroked on their backs. Sharks can be flipped and they become immobile (not always). Everyone knows how Possums do it – they play Possum.

Now, since some sharks can’t breathe when they stop moving, due to something called ram ventilation, they drown. And isn’t that perfect for our Killer!

The killer whale  flips the shark, puts it to sleep. The shark stops breathing and dies. Then the killer whale goes and rips apart the tongue and liver of the shark, because that is all it eats. All the other parts of the dead shark drop to the sea bed.

Even these uneaten parts don’t go to waste, the other sea creatures have the time of their life eating them. They probably thank the odd little habit of the killer whale – the habit of eating just the liver and leaving everything else.

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Bizarre Creature – The Tongue Eating Parasite

By Anupum Pant

Background

Firstly, if you are eating something, or you are weak at heart, then go away. It isn’t going to be a pleasant one today because we are going to look at a really bizarre, and probably one of the most grossest creature ever – The tongue eating parasite.

Not that it is really needed here, but in case someone comes searching for it, the scientific name of this isopod is Cymothoa Exigua. It is one of those very large group of animals that includes crabs and lobster – called Crustacean. This one lives in the ocean and is parasitic. That means this creature lives and benefits at the expense of the other, called the host (fish in this case).

Changing Sex

Protandry hermaphroditism: Another interesting thing about these isopods is that the adult males can turn themselves into females. When a creature changes sex from male to female, it is called Protandry. This changing of sex at some point in life is called Sequential hermaphroditism. So, the tongue eating parasite is a Protandric Hermaphrodite. But that isn’t even what we came here for…The main tongue eating part is coming…

The Life of Cymothoa Exigua

The life cycle of this parasite starts with these little ones attaching themselves to gills of, say a Snapper(or others). They enter the body of a fish through gills. When they mature inside, all of them are males. Later, since they are Protandric Hermaphrodites, one of these matured males turns into a female. During this time the males are still attached to the gill arches.

The male that turns into a female, goes to the base of the tongue of this fish and attaches itself to it. It feeds on the tongue and destroys it. Then the parasite attaches itself to the stub and starts acting as a prosthetic tongue!

If you are not in a mood to read, the woman in the video below explains it nicely.

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Tiger Fish Jumps Out of Water and Catches Flying Birds

By Anupum Pant

It is normal for birds to swoop down and catch fish from water. But, since 1940s, stories about a meter-long-demonic-African-fish leaping out of water to catch birds in mid-air have been told. They were only stories; no one had seen the actual occurrence…Until now.

Recently, a video of it happening was captured by a team of researchers from North-West University in Potchefstroom, South Africa, and was posted on YouTube. As expected, the video went viral. Who wouldn’t love watching a fish-eating a bird! I put it on repeat and must have watched it 10 times already.

In the video you see a Tiger fish (Hydrocynus vittatus – literally means a ‘spotted water dog’) that lives in African fresh waters. It is one of the largest predators there and lives with a larger cousin, the Giant Tiger fish (Hydrocynus goliath). The Tiger fish can measure as much as 1 meter in length. On the other hand, giant tiger fish (not seen here) can reach up to 1.5 meters in length.

Taking shots around the South African lake in the Mapungubwe National Park, they were not really expecting to record a video in which a fish would fly out of the water and catch a swallow. Rather they were there to study migration and habitat at the lake. The team was surprised to see this. The director said:

“The whole action of jumping and catching the swallow in flight happens so incredibly quickly that after we first saw it, it took all of us a while to really fully comprehend what we had just seen.”

Given that a fish in water, or even human beings for that matter, cannot see beyond a specific window (The Underwater Optical Man-hole), this fish does an amazing job of tracking and striking a bird in mid-flight with so much precision. Cheers for that Mr. Tiger Fish.

Agreed the video isn’t clear, but it the first of its kind. Soon, I hope, we’ll see HD, NatGeo quality videos. Watch it on video here: [Video]

Pacific Leaping Blenny – Fish Lives on Land

By Anupum Pant

Scientific name: Alticus arnoldorum

After having seen animals that live on for centuries, fish that have legs and several others, another fascinating animal joins the list at AweSci today. The Pacific Leaping Blenny – A fish that, unlike every other extant specie of fish, lives on land.

Wait! What?

The Pacific Leaping Blenny is a 2-4 inches long fish that is found on reefs in Samoa, Marianas, Society, and Cook Islands, in the western and southern Pacific Ocean. For all its life, this fish stays on land. It breathes through its gills and partly through its skin.

During the few hours when the tide is at a normal level, such that the waves are just strong enough to reach them and not enough to pull them back into water, these fish take care of their business on land. They need the water to hit them because it keeps their skin wet. Which in turn, lets them breathe through their gills and skin. As long as their skin is moist, they can live out of water indefinitely. So much that they have been officially classified as a terrestrial specie. They would suffocate if their skin dries off completely.

Their fascinating camouflage

It is fascinating to see an existing example of how ancient sea dwelling creatures must have first evolved. At these times when we have great predators waiting on land to immediately end this transitional specie, this fish does a great job of hiding itself from them. And given their poor speed on land, that is how they survive on these rocky shores. They have developed a specialized kind of camouflage that makes it difficult for a predator to find and kill them. As you can see in the picture above, they have a skin color that matches very well with the surrounding reefs/rocks.

How do they move on land?

Since they don’t have legs, that is exactly the question that hit my mind when I first read about these creatures. Turns out, for movement on land, they have developed a very peculiar kind of a movement style. They twist their tails, load up the tension and then release to leap. This sequence happens too quickly to notice easily through naked eyes. So, picked off directly from the Wikipedia page, here we have a slow motion video of this fish leaping off.

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The Underwater Optical Man-hole

By Anupum Pant

Agreed, sometimes, when you find yourself being interrogated in a room covered with one-way mirrors, you can’t see the people who are observing you; Instead, you see yourself in the mirrors. Otherwise, If you can see something, it seems normal to assume that the thing can see you too.

A trout’s window to the outside world is something similar to what a person in the interrogation room experiences. However, unlike the person, a fish can actually see things that are out of the water, but the view is very limited.

The Snell’s Window

When a fish looks up from water, it sees only a circular window of light, from under the water surface. Everything that lies outside of this circle is darker. This darker area of vision is replaced by the reflection of the sea/lake bed (where there is no source of light to illuminate it). This effect isn’t due to any limitations of a fish’s eye. In fact, even human divers see only a circle of light when they are under water. This circle is called the Snell’s Window or the optical man-hole.

Irrespective of the fish’s visual acuity, some physical properties of water and air get together and have a great effects on what a fish can see. It sees a circle with diameter calculated by the Snell’s equation.
In short, the window is about 2.3 times as wide as the fish’s depth. So, a fish can see more if it goes deeper. At a depth of 1 meter, it can clearly see things on a circle that is 2.3 m wide on the surface of water.

So, even if you can see a fish in water, it will be foolish to assume that the fish can see you too. Some times it can’t. It looks something like this from under water:

In Wikipedia’s words:

Snell’s window is a phenomenon by which an underwater viewer sees everything above the surface through a cone of light of width of about 96 degrees.

Why does it happen?

It happens due to a simple optical phenomenon called the total internal reflection.
The physics behind this phenomenon can be read here. [Read here]

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Raining Frogs and Fish

By Anupum Pant

Raining cats and dogs is a bit unlikely, but there is nothing wrong about saying, “it is raining frogs and fish”. It happens more often than you think. So, don’t be alarmed if one day you wake up and find fish on your terrace.

When we talk about rain, the one place in India which stands out is Kerala. As we’ve seen in a previous post that Kerala has seen red rains, it has also seen raining fish. This isn’t a joke. On February 12, 2008, people actually saw fish falling down from the sky.

Not just that. I’ve seen reports of water birds, tomatoes, coal, and even a boats falling from the sky.

Raining Animals

After a few moments of awe, when you look at the occurrence of raining animals with the science microscope, you’ll find that it is not something very extraordinary. In fact, there is a whole Wikipedia page on raining animals. It turns out, several places around the world have experienced raining frogs, fish, spiders, worms etc. And as always, science has an explanation for it.

How does it happen?

Water Sprouts: When tornadoes move on land, they can pick up trucks, houses, trees and what not. They suck up several things from the ground and cause total destruction along the path they travel. But, when such storms travel on water, they suck up water, fish and of course, frogs.

This experiment proves how a low pressure can pick up things. – [Experiment]

These things can stay up with the storm for a long time. And eventually when the storm comes on land and weakens the animals may drop down with rain. As a result, we see fish and frogs raining from the heavens.

Sharks Are Not So Bad After All

By Anupum Pant

Sharks have been on earth for millions of years more than we have been here. Also, they haven’t changed much since a long time. The kind of sharks we see today, were the same sharks that existed 350 million years ago.

That means, modern sharks have lived happily for millions of years without eating humans. Even today, they aren’t very keen on killing us for food. They simply aren’t designed (or haven’t evolved) to do that. Humans were never a part of their normal diet. Instead, they normally feed on small fish. While a few other species of sharks may eat seals, sea lions and other mammals too. In fact, they can go on for months without food.

Funny as it may sound, sharks are scared of humans. When a shark sees a human in water, it gets confused and scared. It goes near to check,  and this usually results in an accidental bite. They don’t kill humans out of aggression. With 15 rows of razor sharp teeth on each jaw, even their gentle bites may kill a person. About only 20 out of 300 species of sharks are reported to have been involved in accidents with human beings.  About 100 such accidents occur every year.

Not being insensitive about human deaths: Can you estimate how many people do sharks kill every year? The answer is 10. Ten people, on an average are killed by shark bites every year. That is about 1/15 th of number of people killed by coconuts every year*
*Note: “150 people are killed by coconuts every year”, is a popular urban legend. The coconut death figure is a crude estimate or just a figure pulled out of thin air.

Nevertheless, the number of people killed by sharks every year is very very less (again, even a single human death isn’t really ‘less’). I’d rather not use statistics to prove my point. [image]

Why are sharks scared of us? … Why shouldn’t they be?
We kill about 100 million sharks every year. That is such a huge number when compared to number of people sharks kill every year. Again, statistics could be deceiving here. But we do get an idea. There is a massive difference in the number.
Why? Humans catch sharks for their meat, internal organs and skin,  to make products such as shark fin soup, lubricants, and leather etc. Some times, fins are cut and live sharks are thrown back into the sea, crippled. This eventually kills them due to excessive bleeding or other obvious reasons.

It is ironically that we move into their natural habitat and in turn blame sharks for destroying our boats, surf boards. Moreover, we are shocked to hear about reports of shark attacks on humans. Shouldn’t it be the other way round? We should stop looking at sharks as if they are the monsters; we are. At the same time, that doesn’t mean you should risk your life by going in shark waters to give it a high-five.

Random Science Fact:  

Only 14% of the Earth’s species are known to us. 75% of all the species on Earth will be gone within the next 300 years. Think about those species which will go extinct while we are here, and we’ll never know about them.

Axolotl – A Walking Fish That can Regenerate Limbs

By Anupum Pant

If you are looking at an Axolotl for the first time, it will confuse you. With an oddly shaped body that resembles both a catfish and a salamander, you’ll wonder if it lives in water or on land. [Image]

What is it?

A fish? Axolotl, commonly known as the Mexican Walking Fish, isn’t actually a fish. It is an amphibian, which means it has both lungs and gills. They almost never come out of water, hold their breath and take in oxygen using their gills (those three pairs of parts coming out at the back of its head are the gills). They can hold their breath for a year, beat that Mr. David Blaine.

Or Salamanders? They are closely related to salamanders and interestingly the adult Axolotls look like baby Salamanders. They have long abandoned the usual amphibian-transformation from a larva stage to an adult. Unlike Salamanders, they don’t transform into adults that can live outside water. They stay in water and walk around on the water-bed.

However, strange species of Axolotl was once delivered to a zoologist Auguste Duméril, which had somehow transformed like salamanders and would happily come out of water. But this transformation (metamorphosis) shortened their life span. Later it was found that this process can be artificially triggered by injecting iodine. (Do NOT try this at home)

As pets: Today, these animals are fairly common and are used as exotic pets all around the world. Especially in Japan, people love to have them in their aquariums.

Side note: Like several other Pokémon based on real animals, Whooper and Mudkip were actually based on Axolotls.

Regenerative Powers

Besides having the ability to walk underwater and its unusual appearance, there is something that is much more interesting about them. Unlike, almost any other vertebrate, they have the power to regenerate various cells. Not just cells, Axolotls can regenerate complete body parts – limbs, gills, eyes, kidneys, even large portions of its liver and its heart muscle. Even portions of its spine and brain can be regenerated. They are able to grow back a severed limb in span of few months. This is the reason scientists love these creatures and conduct a number of studies on them every year.