Treasures of Nature

Friday 16 February 2024

Patch or Soot?

We all know that pollution causes a lot of harm to the plants and animals around us. But did you know that some living beings can even be accurately reflect the levels of pollution in their surroundings? Due to this ability, they are often considered as reliable indicators of pollution, and are called bioindicators.

Well, these peculiar living beings are called lichens.

Lichens are formed by a symbiotic association between algae and fungi. In such an association, both the members help each other to thrive. The algae are plant like organisms that can prepare their own food by photosynthesis. They provide food to the fungi. The fungi cannot prepare their own food, but they can provide a structure and protection to the algae, which are otherwise delicate.

Lichens grow on barks of trees, often appearing as white patches. They are often called the mossy lichens.

In highly industrialized areas, where air pollution by sulfur dioxide is common, lichens are unable to survive. In these areas, the barks of trees do not show the white patches of lichen. In fact, higher the levels of sulfur dioxide in the air, fewer the lichens seen on the trees.

However, there is another kind of lichen, that is much more tolerant to air pollution and high levels of sulfur dioxide in air. This sturdier cousin of the mossy lichen is called the crusty lichen.

Areas where even these sturdier crusty lichens cannot grow, are considered very highly polluted.

In fact, the barks of trees in these highly polluted areas are often covered by black soot, which is also another air pollutant released by factories. Hence, instead of appearing white and patchy, the barks of trees appear black.

These lichens are our friends and have always warned us about pollution going above permissible levels. Although air pollution harms other living beings in the world, it harms humans too! We are wise enough to understand that we must save ourselves from the ill effects of pollution. It is for us to not only decode the signals of these bioindicators, but also to save the entire ecosystem from the suffering due to actions of humans

Friday 3 May 2019

Food for one…..

We know that the word ‘Karma’ has a spiritual meaning. You may wonder if the word “Trung trung karmo” has a similar meaning. Well – it is the local name of the black-necked crane, that is believed to be a carrier of the Dalai Lama. Hence, the sightings of this bird are considered to bring luck, and often cause a stir….

These birds are found in the high-altitude marshes of Tibet and Ladakh in the breeding season. They migrate to parts of Bhutan and Arunachal Pradesh in winter. According to the IUCN, these birds have been classified as a ‘vulnerable’ species.

The black necked cranes migrating to the Sangte and Chugh valleys in Arunchal Pradesh feed on insects in the paddy fields. But due to change in the variety of rice grown in these valleys in the past six to seven years, the insects are not drawn to the paddy fields after the harvest. Experts think this could be a reason for the decrease in the numbers of black necked cranes visiting Arunachal Pradesh every year.

The introduction of new rice varieties has decreased the number of people going hungry in these regions, but the sightings of the bird are becoming rarer. Another instance of Karma – how food for one could be another’s ………

References:

1. Birds of Shangri-la

2. IUCN red list

3. Species field guide

Monday 30 November 2015

Wide or White?

White Rhino

Recently, one of the last four northern white rhinos in the world died in captivity. Now only three members of this endangered species survive.

The efforts to conserve the Northern White Rhino were initially fruitful, but the resurgence of poaching activity has now brought them to the near extinction. These animals are killed for their horns, which are used to make traditional medicines for many major human diseases and also to make decorative articles.

Actually, the white rhino is not really white. It is grey. There is very little difference in the colour of the black rhino and the white rhino. Then why is it called so? The answer to this lies in the more appropriate name of the white rhino: it is also called the square-lipped rhinoceros.

When Dutch settlers in Africa saw this species of rhinoceros, they realized that these had a wider mouth than the other rhinos. So the Dutch called these rhinos ‘wijd rhinos’. ‘Wijd’ in dutch means ‘wide’. However, the English settlers that followed them mistranslated the word ‘Wijd’ word as ‘White’ – hence the name ‘White Rhino’.

The White rhinos have a wider squared upper lip, which helps them to bite off short grass. The black rhino on the other hand as a pointed upper lip which helps it to bite off leaves from trees.

Another theory about their name says that the white rhinos, although actually grey, appear white because their backs are often covered with white bird droppings.

One male and two female northern white rhinos left in this world are currently kept captive under high security in a conservatory in Kenya, to protect them from poachers.


Black Rhino

References:

1. http://www.iucnredlist.org/details/4185/0

2. http://animals.nationalgeographic.com/animals/mammals/white-rhinoceros/

3. https://www.savetherhino.org/rhino_info/species_of_rhino/white_rhinos/factfile_white_rhino

Tuesday 29 September 2015

The story of the horns

Do you recognize this picture? A devil’s head with horns?

No. In fact it is a close-up picture of a seed. What look like horns are actually hooks.

You might wonder what hooks are doing on a seed! These hooks allow the seed th stick to the fur of an animal. When the animal moves from one place to another, it carries the seed along with it. When the seed falls off the animal to the ground, it has travelled a large distance from the parent plant. Like other modes of seed dispersal, animal dispersal of seeds also helps plants to colonize new habitats.

This is just one mode of seed dispersal. A more common mode of animal dispersal of seeds is through animal droppings. Generally frugivores i.e. fruit eating animals consume the seed of the fruit with their fruit meal. They are unable to digest the seed, which is then thrown out of their body through the droppings, at a new location where the animal has reached. This seed germinates where it falls, giving rise to a new plant.

Some animal dispersed seeds are covered with a slimy substance which helps them to stick to the bodies of birds. The birds fly over large distances and carry the seeds along with them.

References:

1. http://www.britannica.com/topic/animal-dispersal-in-rainforests-1673040

2, http://theseedsite.co.uk/sdanimal.html

3. http://www.webpages.uidaho.edu/range556/appl_behave/projects/seed_dispersal.html

Wednesday 19 August 2015

The Wind Tales

I was walking along a crowded road in the middle of the city. Like many of our roads, this road too was lined with huge old trees. Right there on the footpath, I found something that we were fascinated by as children. Many nature enthusiasts fondly call it the ‘monkey biscuit’, since monkeys nibble at it.

This is the seed of a plant called Angsana or Petrocarpus indicus. What makes it special are the wing like papery structures that surround it, and make it ‘fly’. This is one of the many types of seeds that are dispersed by wind. The wind carries these seeds over large distances. If the seed lands on a surface that is suitable for germination, it can grow into a new plant there.

Angsana seeds

Plants of the genus Shorea have structures similar to blades of a helicopter attached to their small fruits. These plants disperse their entire fruits with the help of the wind. The seeds, of course, are inside the fruit!

Shorea fruits

The Dandelion seeds have feathery bristles around it which help it to float in air like a parachute.

Dandelion seeds

The structure of seeds of Alsomitra macrocarpa inspired the structure of the first gliders.

Alsomitra macrocarpa seed

Dispersal of seeds in this way helps the propagation of the species to distant places. If the offspring of the same plant grew in close proximity with each other, they would have to compete for food, water and space. Dispersal of seeds to faraway places ensures that this problem is solved.

References:

1. http://theseedsite.co.uk/sdwind.html

2. http://waynesword.palomar.edu/plfeb99.htm

Sunday 13 January 2013

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.

Saturday 17 November 2012

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.