Tag: motion

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 Sun’s Unusual Behavior – Seen from Mercury

by Anupum Pant

The sun – as seen from Earth

For most of us living on Earth (closer to the equator), the sun has followed a simple path throughout the years. It rises, goes up at noon and then sets for rest of the day. It is a simple straight line for the complete year.
For people living a little away from the equator, things get a bit interesting. There, the summer sun at noon is overhead, but the winter sun is low at noon, not overhead. It isn’t very easy for a person living near the equator to grasp this phenomenon well. You’ll have to go there and see for yourself. Or simply, the simulator at the end of this paragraph will help you understand it better.
At poles, the sun almost moves horizontally for many days. It keeps on making a horizontal circle around you. There, it is day for 6 months and night for the next 6 months. [Here is a sun path simulator for Earth]

However, nowhere on earth, things get as interesting as they get in the skies of Mercury.

The sun – as seen from Mercury

On Mercury, the sun appears to briefly reverse its usual east to west motion once every Mercurian year. The effect is visible from any place on Mercury, but there are certain places on its surface, where an observer would be able to see the Sun rise about halfway, reverse and set, and then rise again, all within the same day. It is indeed an unusual performance which isn’t easy for us Earthlings to digest. [See animation in the next paragraph]

Why does it happen?

Let us consider a simpler analogy – some planets (like Mars), as seen from earth, take a similar path. [see the animation for Mars’s path as seen from earth]

The planets, including Earth, all travel around the Sun in a continuous orbit. We can see them make their way across the sky in a straight line usually. However, every now and then a planet appears to turn around. After turning around, it appears to move back the way it came. This is called a retrograde orbit and is caused due to the difference in speeds at which the planets circle the Sun.

So, as we see Mars do a reverse from earth, a similar motion of sun is observed from the surface of Mercury.

[Apparent Retrograde Motion – Wikipedia]