Jaws

I read in the newspaper the other day, that a man was arrested for trying to smuggle shark teeth into India. Import of shark teeth is prohibited in the country under the Wild Life Protection  Act of 1972.

But why do people try to smuggle shark teeth? What makes shark teeth so precious?

Shark teeth are not just teeth. They are fossils. Sharks do not have any bones in their body. Their skeleton is made up of a softer tissue called cartilage. When a shark dies, the cartilage decays along with the rest of the body. What remains of dead sharks are only the teeth. These teeth get covered with minerals and sand, and hence do not get corroded. The get fossilized. It takes about 10 000 years for the fossils to get formed.

These fossilized teeth lying on the sea bed often get washed ashore by the waves. They can be spotted by people in the sands at low tide.

During the renaissance period, people mistook these shark teeth for fossilized tongues of dragons and snakes. They were used to cure snake bite. Due to this quality, people considered them lucky, and shark teeth came to used as charms for good luck.

Now that shark teeth have been recognized for what they are, they have become precious commodities and collector’s items. The teeth of the giant pre-historic shark, the Megalodon are the most valuable of all. They can measure upto 7 inches and weigh more than a pound.

Fossilized shark teeth appear brown or blue because of minerals deposited on them. Shark teeth are commonly found on beaches of California. Sharks loose one tooth per week, on an average, while biting off prey. This is because their teeth are not attached to roots like the human teeth. And once a tooth falls off, it is immediately replaced by the one behind it. Yes, sharks have multiple rows of teeth.

Further reading:

1. http://www.enchantedlearning.com/subjects/sharks/anatomy/Teeth.shtml
2. http://www.veniceflorida.com/shark.htm

Noisy Flights

Why is the humming bird called so?

It is because of the humming sound it makes while flying.

Have you ever tried running and singing at the same time? It would be impossible wouldn’t it? You would start panting within no time! Then how does the humming bird manage this?

The secret is that the sound made by this bird during the flight is not vocal at all. It is caused by the rapid beating of its little wings, just like bees and dragon flies. This little bird beats its wings around 60 to 80 times a second!

In fact, the sounds made by the feathers of this bird are not restricted to humming alone. The elaborate courtship displays of humming birds comprise of a bomb dive from a great height. The dive is accompanied by a loud chirp. But this chirp again, is not vocal. During the dive, the bird spreads out its tail feathers, just for 60 milliseconds. The feathers vibrate for this brief period and the air passing across them gives the chirp that attracts the female’s attention.

Humming birds are the smallest vertebrates, the smallest hummingbird, the Bee Hummingbird being no more than 2.25 inches long. These creatures can hover at one place in air for a long period of time. They are capable of flying forwards, backwards, upwards and downwards, an incredible feat that no other bird is capable of! This is possible because they have wings that rotate through 180^o. Unlike most birds that flap their wings back and forth to fly, hummingbirds move their wings in the shape of an eight, so that they can move in any direction. They have strong pectoral muscles that make this possible.

Hummingbirds are mainly found in the American continents. The feed on nectar from flowers, from where they get their sugars. For proteins, they feed on insects.

Further reading:

1.http://birding.about.com/od/birdprofiles/a/whatishummingbird.htm

2.http://www.sciencedaily.com/releases/2012/09/120927091924.htm

3.http://www.sciencedaily.com/releases/2010/11/101121122532.htm

4.http://www.youtube.com/watch?v=l3XT6qoNMMQ

Forests in the sea

Whenever we talk of forests, we visualize a vast expanse of land with lots of large trees and thick lush green undergrowth…..and a variety of big and small animals and insects living in the midst of this vegetation. We may be well aware that there are different types of forests like tropical evergreen forests, coniferous forests of the temperate region, deciduous forests etc..Grasslands are also forests.

But how many of us are aware that there are forests under the sea?

Along the Pacific coasts of the North America, South America, Australia and near South Africa, the ocean beds are densely populated with the Giant Kelp. These are large algae that grow to about 90 feet high. They are brown algae and absorb light using the pigment fucoxanthin which gives them their brown colour. Large numbers of these algae grow close together forming “Kelp forests”.

Kelp grow in waters that are nutrient rich, at a temperature below 21^oC. They grow in shallow waters near the coast so that they receive sufficient sunlight.

Kelp forests are the most diverse marine ecosystems. A variety of invertebrates, fish, marine mammals and birds live in and around these forests. Large creatures like sea lions, seals, otters, or even whales may take shelter in these forests to escape from storms or predators. Kelps are known to calm down sea storms because they weaken the currents and waves. They protect the shore from wave action.

Sea Urchins feed on Kelp to such a large extent that at times they raze the entire forest to ground and prevent it from regrowing. This ecological imbalance is however taken care of if there are enough Sea Otters to prey on the urchins. Thus, the Sea Otter is a keystone species of this ecosystem and prevents it from collapsing.

In today’s times of energy crisis, scientists are trying to use Kelp as a source of renewable energy. They are trying to make fuel from Kelp using bacteria.

Further reading:

1.http://theweek.com/article/index/223581/the-mutant-bacteria-that-turns-seaweed-into-fuelnbsp

2.http://www.csupomona.edu/~biotrek/posters/kelp_anatomy.pdf

3.www.youtube.com/watch?v=ZQb9ZFWfNZE

Fish with a difference

As a habit, I go to the beach for a walk every morning. As dirty as the beach is, we rarely see any sea animals there – except crabs. But this morning, the tide was low, and I ventured far into the water, in the hope of seeing something more. And I did see something……  

A unique little creature. 

The sand was wet, with many little puddles. And in these puddles I could see some animals. They were brown in colour, about three inches long, one inch thick. In water, they would wriggle continuously. Occasionally, one would come out of the puddle, and jump about in the wet sand.

These creatures were none other than the mudskippers. They are amphibious fish. Yes, you got it right – amphibious fish. That means they can live on land as well as in water. These are one of the few species of fish that can survive when out of water.

We are aware that most land animals breathe air through lungs. That is where we get oxygen from. Fish have gills instead of lungs, and through these, they absorb the oxygen dissolved in water. When most fish come out of water, the walls of their gills stick together, so that they can no more breathe. Ultimately they die.

But what sets the mudskipper apart is its ability to breathe when out of water. Like other fish it has got gills too. But around these gills it has large chambers in which it can store water, with a bubble of air, before coming to land. So although the mudskipper is on land, its gills are surrounded by water, so that the walls don’t stick together.

The mudskipper can also breathe through its skin, as long as the skin remains moist. So it has to return to water time and again for a splash. In fact, some mudskippers remain close to water, with their tails always dipped in water. This led some early observers to believe that mudskippers breathe through their tails!

Where does the mudskipper get such a funny name from? Well – when on land, they use their front fins to move about. Both the fins are used together, like a man walking on crutches. They move about in a series of ‘skips’ - hence the name. To attract females, the males may propel themselves into air as high as two feet, with the help of these fins. Some can even stand on their tails!

Next time you visit a beach during low tide, watch out for these little wonders……  

Further reading:

1. http://www.youtube.com/watch?v=KurTiX4FDuQ

2. http://worldfishcenter.org/Naga/Naga25-3&4/pdf/NAGA_25no3n4_features_d.pdf

3. http://free-journal.umm.ac.id/files/file/09_2445_ns0805_79_89.pdf

4. http://www.mudskipper.it/Profile_file/Polgar&Crosa09_online.pdf

Jumping jacks

Had been to Konkan for a vacation last year. It was a beautiful winter morning. At a point in the ghats, we stopped at a tea stall to enjoy the view with a glass of hot chai.

As we chatted with the chaiwalla, he told us the story of the fisherman who saw dolphins in the sea a few years ago. As this news spread, these dolphins became a tourist attraction. Now, many launches are available that take tourists into the sea to see these animals of titanic fame.

We decided to go too! The sea was rough, and the boat rocked. But we continued undaunted. The boatman pointed out into the sea. And lo and behold – we could see a dolphin jump out of the water and back into it….several times. Oh! What a beautiful sight!

But have we ever wondered – what makes these ‘fish’ come out of water?

And not only dolphins, even whales show this behavior. Why?

The answer lies in the basic fact that dolphins and whales, although often mistaken to be, are not fish. So, unlike fish, they do not breathe underwater through gills. They are mammals, and like humans, have lungs for breathing. They do not take in the oxygen dissolved in water, like fish. They breathe oxygen from air.

We cannot hold our breath underwater for a long time. We have to come to the surface of water to breathe in again, unless we are carrying oxygen cylinders. Similarly, the dolphin comes to the surface of water to breathe air through a hole on its back that functions as a nostril. It takes in sufficient amount of air into the lungs and goes underwater again. It can stay underwater for about fifteen minutes. Whales breathe the same way, but some of them can remain underwater for upto an hour!

But doesn’t the water enter the lungs of these animals and choke them? No – at the base of their breathing hole, they have a flap which closes as they dive. This flap keeps the water out of the lungs. Also, as they go deeper, although the pressure of the surrounding water increases, their lungs collapse, and the water is kept out.

Further reading:

1. http://library.thinkquest.org/17963/respiratory-system.html

2. http://understanddolphins.tripod.com/dolphinblowholeandbreathing.html

3. http://www.youtube.com/watch?v=S6hNWZQeFzc

  

In the dark

The streets of Gotham were pitch dark because of the power cut. It was almost midnight. Tom could barely see a few feet ahead. As he turned the corner, he became aware of someone behind him. The footsteps came closer and closer, and before he knew it, someone nabbed him by the throat, and threw him on the floor. The masked man pointed a knife at him and began searching him for his wallet. Tom lay helpless on the ground, too scared to react.

Suddenly, something swooped down and pushed the robber over. The figure in the dark started bashing the robber. Thankful, Tom got up to his feet. He wondered who his savior was. And then, he saw the savior’s outline in the dark. It was none other than batman himself!

Of course! Who else could have spotted danger in the dark!

Yes. Bats are nocturnal .i.e. they rest during the day and hunt at night. But how do they find their prey in the dark? The do it using a special ability called echolocation. As bats fly around in search of prey in the dark, they produce sounds by clicking their tongues or contracting their voice boxes. These sounds are very high-pitched, and cannot be heard by humans. These sound waves travel through air. When they hit a flying insect, they bounce off the insect, and start travelling back towards the bat. Using its ears, the bat detects these reflected waves and knows where the insect is.

The bat knows if the insect is on its left or right depending on which ear the waves reach first. It can also make out the size of the insect depending on the loudness of the echo. A smaller insect will reflect less waves, giving a softer echo. On the basis of the pitch of the echo, the bat knows in which direction the insect is moving. An insect that is moving towards the bat will give a higher pitched echo than the original sound, whereas an insect moving away from the bat will give a lower pitched echo. The bats mind unconsciously interprets this information, the way we humans unconsciously interpret the information from our eyes or ears as sight or sound.

The bat can also use this ability to locate stationery objects, and hence to find its way in the dark.

Further reading:

1.http://www.batcon.org/index.php/all-about-bats/intro-to-bats.html

2. http://www.youtube.com/watch?v=gZxLUNHEmPw

Fine Fiddle

Every fiddler had a fine fiddle,

and a very fine fiddle had he;

Oh there's none so rare as can compare

With King Cole and his fiddlers three.

We have all heard of King Cole’s famous fiddlers three. They played fine tunes to please their master, the king. But have you ever heard of the crab that plays the fiddle?

I am talking about the ‘fiddler crab’. This species of crab is commonly found on Indian beaches. It measures about one to two inches, and can be identified by its distinctly visible ‘fiddle’.

In the males of this species, one of the claws is extremely large, much larger than the other claw, and sometimes even larger than the entire body of the crab. This claw is often brightly coloured, and is meant for attracting the female. During courtship, the males engage in a fight in which they use their large claw.

The fiddler crab feeds on algae, fungi , dead plants etc….

When this crab feeds, it picks up food from the ground and puts it into its mouth. It repeats this action several times, rapidly. It uses its small claw to feed. The larger claw remains motionless. The small claw thus moves again and again across the large claw. So the overall action looks as if the large claw is the fiddle, and the crab is playing it with the small claw!

Watching this tiny fiddler is a joy indeed!


1. http://wildphotos.net/facts/Fiddlercrab.asp?page=/facts/Fiddlercrab.asp
2. www.youtube.com/watch?v=qPAA9y7CRqo
3. http://www.dnr.sc.gov/cwcs/pdf/FiddlerCrab.pdf