Saturday, March 13, 2010

Sinharaja Rain forest





Sinharaja Forest Reserve is a national park and a biodiversity hotspot in Sri Lanka. It is of international significance and has been designated a Biosphere Reserve and World Heritage Site by UNESCO.
The hilly virgin rainforest, part of the Sri Lanka lowland rain forests ecoregion, was saved from the worst of commercial logging by its inaccessibility, and was designated a World Biosphere Reserve in 1978 and a World Heritage Site in 1988. The reserve's name translates as Kingdom of the Lion.
The reserve is only 21 km from east to west, and a maximum of 7 km from north to south, but it is a treasure trove of endemic species, including trees, insects, amphibians, reptiles, birds and mammals.
Because of the dense vegetation, wildlife is not as easily seen as at dry-zone national parks such as Yala. There are about 3 elephants and the 15 or so leopards are rarely seen. The commonest larger mammal is the endemic Purple-faced Langur.
An interesting phenomenon is that birds tend to move in mixed feeding flocks, invariably led by the fearless Greater Racket-tailed Drongo and the noisy Orange-billed Babbler. Of Sri Lanka's 26 endemic birds, the 20 rainforest species all occur here, including the elusive Red-faced Malkoha, Green-billed Coucal and Sri Lanka Blue Magpie.
Reptiles include the endemic Green pit viper and Hump-nosed vipers, and there are a large variety of amphibians, especially tree frogs. Invertebrates include the endemic Common Birdwing butterfly and the inevitable leeches.

The Amazon Rain forest




The Amazon rainforest (Brazilian Portuguese: Floresta Amazônica or Amazônia; Spanish: Selva Amazónica or Amazonia), also known as Amazonia, or the Amazon jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America. This basin encompasses seven million square kilometers (1.7 billion acres), of which five and a half million square kilometers (1.4 billion acres) are covered by the rainforest. This region includes territory belonging to nine nations. The majority of the forest is contained within Brazil, with 60% of the rainforest, followed by Peru with 13%, and with minor amounts in Colombia, Venezuela, Ecuador, Bolivia, Guyana, Suriname, and French Guiana. States or departments in four nations bear the name Amazonas after it. The Amazon represents over half of the planet's remaining rainforests, and it comprises the largest and most species-rich tract of tropical rainforest in the world.
The Amazon rainforest was short-listed in 2008 as a candidate to one of the New7Wonders of Nature by the New Seven Wonders of the World Foundation. As of February 2009 the Amazon was ranking first in Group E, the category for forests, national parks and nature reserves

Athropod


An arthropod is an invertebrate animal having an exoskeleton (external skeleton), a segmented body, and jointed appendages. Arthropods are members of the Phylum Arthropoda (from Greek ἄρθρον arthron, "joint", and ποδός podos "foot", which together mean "jointed feet"), and include the insects, arachnids, crustaceans, and others. Arthropods are characterized by their jointed limbs and cuticles, which are mainly made of α-chitin; the cuticles of crustaceans are also biomineralized with calcium carbonate. The rigid cuticle inhibits growth, so arthropods replace it periodically by molting. The arthropod body plan consists of repeated segments, each with a pair of appendages. It is so versatile that they have been compared to Swiss Army knives, and it has enabled them to become the most species-rich members of all ecological guilds in most environments. They have over a million described species, making up more than 80% of all described living species, and are one of only two animal groups that are really successful in dry environments – the other being the amniotes. They range in size from microscopic plankton up to forms a few meters long.
Arthropods' primary internal cavity is a hemocoel, which accommodates their internal organs and through which their blood circulates; they have open circulatory systems. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. Their nervous system is "ladder-like", with paired ventral nerve cords running through all segments and forming paired ganglia in each segment. Their heads are formed by fusion of varying numbers of segments, and their brains are formed by fusion of the ganglia of these segments and encircle the esophagus. The respiratory and excretory systems of arthropods vary, depending as much on their environment as on the subphylum to which they belong.
Their vision relies on various combinations of compound eyes and pigment-pit ocelli: in most species the ocelli can only detect the direction from which light is coming, and the compound eyes are the main source of information, but the main eyes of spiders are ocelli that can form images and, in a few cases, can swivel to track prey. Arthropods also have a wide range of chemical and mechanical sensors, mostly based on modifications of the many setae (bristles) that project through their cuticles.
Arthropods' methods of reproduction and development are diverse; all terrestrial species use internal fertilization, but this is often by indirect transfer of the sperm via an appendage or the ground, rather than by direct injection. Aquatic species use either internal or external fertilization. Almost all arthropods lay eggs, except for scorpions, who give birth to live young after the eggs have hatched inside the mother. Arthropod hatchlings vary from miniature adults to grubs and caterpillars that lack jointed limbs and eventually undergo a total metamorphosis to produce the adult form. The level of maternal care for hatchlings varies from zero to the prolonged care provided by scorpions.
The versatility of the arthropod modular body plan has made it difficult for zoologists and paleontologists to classify them and work out their evolutionary ancestry, which dates back to the Cambrian period. From the late 1950s to late 1970s, it was thought that arthropods were polyphyletic, that is, there was no single arthropod ancestor. Now they are generally regarded as monophyletic. Historically, the closest evolutionary relatives of arthropods were considered to be annelid worms, as both groups have segmented bodies. This hypothesis is by now largely rejected, with annelids and molluscs forming the superphylum Lophotrochozoa. Many analyses support a placement of arthropods with cycloneuralians (or their consistent clades) in a superphylum Ecdysozoa. Overall however, the basal relationships of Metazoa are not yet well resolved. Likewise, the relationships between various arthropod groups are still actively debated.
Although arthropods contribute to human food supply both directly as food and more importantly as pollinators of crops, they also spread some of the most severe diseases and do considerable damage to livestock and crops

Saturday, February 13, 2010

The Mollusca Sea slugs, squid, snails, and scallops


A cuttlefish, a coleoid cephalopod, moves primarily by undulating its body fins.
Mollusca is one of the most diverse groups of animals on the planet, with at least 50,000 living species (and more likely around 200,000). It includes such familiar organisms as snails, octopuses, squid, clams, scallops, oysters, and chitons. Mollusca also includes some lesser known groups like the monoplacophorans, a group once thought to be extinct for millions of years until one was found in 1952 in the deep ocean off the coast of Costa Rica.
Molluscs are a clade of organisms that all have soft bodies which typically have a "head" and a "foot" region. Often their bodies are covered by a hard exoskeleton, as in the shells of snails and clams or the plates of chitons.

A part of almost every ecosystem in the world, molluscs are extremely important members of many ecological communities. They range in distribution from terrestrial mountain tops to the hot vents and cold seeps of the deep sea, and range in size from 20-meter-long giant squid to microscopic aplacophorans, a millimeter or less in length, that live between sand grains.

These creatures have been important to humans throughout history as a source of food, jewelry, tools, and even pets. For example, on the Pacific coast of California, Native Americans consumed large quantities of abalone and especially owl limpets. However, the impact of Native Americans on these molluscan communities pales by comparison to the overharvesting of some molluscan taxa by the United States in the 1960s and 1970s. Species whose members once numbered in the millions, now teeter on the verge of extinction. For example, fewer than 100 white abalone remain after several million individuals were captured and sold as meat in the 1970s. Besides having yummy soft parts, molluscs often have desirable hard parts. The shells of some molluscs are considered quite beautiful and valuable. Molluscs can also be nuisances, such as the common garden snail; and molluscs make up a major component of fouling communities both on docks and on the hulls of ships.


On the left is a marine snail, the California Trivia (Trivia californiana). Here the mantle covers much of the shell. Note how a portion of the mantle is rolled into a tube shape to form the siphon just above the head. At the right is a restoration of one of the largest of all molluscs, the Giant Squid (Architeuthis).
They also have a very long and rich fossil record going back more than 550 million years, making them one of the most common types of organism used by paleontologists to study the history of life.

Monday, February 1, 2010

Astronomers discover cool stars in nearby space


An international team, led by astronomers at the University of Hertfordshire in the United Kingdom, has discovered what may be the coolest sub-stellar body ever found outside our own solar system. Using the United Kingdom Infrared Telescope (UKIRT) in Hawaii, a discovery has been made of an object that is known as a brown dwarf.

What has excited astronomers are its very peculiar colors that actually make it appear either very blue or very red, depending on which part of the spectrum is used to look at it.

The object is known as SDSS 1416+13B, and it is in a wide orbit around a somewhat brighter and warmer brown dwarf, SDSS 1416+13A. The Sloan Digital Sky Survey detected the brighter member of the pair in visible light. By contrast, SDSS 1416+13B is only seen in infrared light. The pair is located between 15 and 50 light-years from the solar system, which is quite close in astronomical terms.

"This looks like being the fourth time in 3 years that the UKIRT has made a record breaking discovery of the coolest known brown dwarf, with an estimated temperature not far above 200° Celsius," said Philip Lucas at the University of Hertfordshire's School of Physics, Astronomy and Mathematics. "We have to be a bit careful about this one because its colors are so different than anything seen before that we don't really understand it yet. Even if it turns out that the low temperature is not quite record breaking, the colors are so extreme that this object will keep a lot of physicists busy trying to explain it."

SDSS 1416+13B was first noticed by Ben Burningham of the University of Hertfordshire as part of a dedicated search for cool brown dwarfs in the UKIRT Infrared Deep Sky Survey (UKIDSS). The object appeared far bluer at near infrared wavelengths than any brown dwarf seen before. A near infrared spectrum taken with the Japanese Subaru Telescope in Hawaii showed that it is a type of brown dwarf called a T dwarf, which has a lot of methane in its atmosphere, but with peculiar features including a big gap at certain wavelengths.

Burningham soon noticed that a previously observed brighter star (SDSS 1416+13A) that appears close by in the UKIDSS discovery image was also a brown dwarf. Team member Sandy Leggett, of the Gemini Observatory, then used the orbiting Spitzer Space Telescope to investigate SDSS 1416+13B at longer wavelengths. She measured its color at mid-infrared wavelengths, which are thought to be the most reliable indicator of temperature, and found that it is the reddest known brown dwarf at these wavelengths by some margin. Comparison with theoretical models of the brown dwarf atmospheres then provided a temperature estimate of about 441° Fahrenheit (227° Celsius).

"The fact that it is a binary companion to a warmer brown dwarf that also has an unusual spectrum is helping us to fill in some gaps in our understanding," said Burningham. "It seems likely that both brown dwarfs are somewhat poor in heavy elements. This can be explained if they are very old, which also fits with the very low temperature of the faint companion."

Too small to be stars, brown dwarfs have masses smaller than stars but larger than gas giant planets like Jupiter. Due to their low temperature, these objects are very faint in visible light, and they are detected by their glow at infrared wavelengths. They were originally dubbed "brown dwarfs" long before any were actually discovered to describe the idea of bodies that were cooler, fainter, and redder than red dwarf stars, with the color brown representing the mix of red and black.