Monday, November 12, 2012

Lion study




The lion (Panthera leo) is one of the four big cats in the genus Panthera and a member of the family Felidae. With some males exceeding 250 kg (550 lb) in weight, it is the second-largest living cat after the tiger. Wild lions currently exist in sub-Saharan Africa and in Asia, with an endangered remnant population in Gir Forest National Park in India, having disappeared from North Africa and Southwest Asia in historic times. Until the late Pleistocene, about 10,000 years ago, the lion was the most widespread large land mammal after humans. They were found in most of Africa, across Eurasia from western Europe to India, and in the Americas from the Yukon to Peru. The lion is a vulnerable species, having seen a major population decline of 30–50% over the past two decades[date missing] in its African range. Lion populations are untenable outside designated reserves and national parks. Although the cause of the decline is not fully understood, habitat loss and conflicts with humans are currently the greatest causes of concern. Within Africa, the West African lion population is particularly endangered.
Lions live for 10–14 years in the wild, while in captivity they can live longer than 20 years. In the wild, males seldom live longer than 10 years, as injuries sustained from continual fighting with rival males greatly reduce their longevity. They typically inhabit savanna and grassland, although they may take to bush and forest. Lions are unusually social compared to other cats. A pride of lions consists of related females and offspring and a small number of adult males. Groups of female lions typically hunt together, preying mostly on large ungulates. Lions are apex and keystone predators, although they scavenge as opportunity allows. While lions do not typically hunt humans, some have been known to do so. Sleeping mainly during the day, lions are primarily nocturnal, although bordering on crepuscular in nature.
Highly distinctive, the male lion is easily recognised by its mane, and its face is one of the most widely recognised animal symbols in human culture. Depictions have existed from the Upper Paleolithic period, with carvings and paintings from the Lascaux and Chauvet Caves, through virtually all ancient and medieval cultures where they once occurred. It has been extensively depicted in sculptures, in paintings, on national flags, and in contemporary films and literature. Lions have been kept in menageries since the time of the Roman Empire, and have been a key species sought for exhibition in zoos over the world since the late 18th century. Zoos are cooperating worldwide in breeding programs for the endangered Asiatic subspecies.
(For more: Wikipedia )

Saturday, September 15, 2012

Cheetah study




The cheetah (Acinonyx jubatus) is a large-sized feline (family Felidae, subfamily Felinae) inhabiting most of Africa and parts of the Middle East. It is the only extant member of the genus Acinonyx. The cheetah can run faster than any other land animal— as fast as 112 to 120 km/h (70 to 75 mph) in short bursts covering distances up to 500 m (1,600 ft), and has the ability to accelerate from 0 to over 100 km/h (62 mph) in three seconds.
This cat is also notable for modifications in the species' paws. It is one of the few felids with semi-retractable claws.

The cheetah has unusually low genetic variability. This is accompanied by a very low sperm count, motility, and deformed flagella. Skin grafts between unrelated cheetahs illustrate the former point in that there is no rejection of the donor skin. It is thought that the species went through a prolonged period of inbreeding following a genetic bottleneck during the last ice age. This suggests that genetic monomorphism did not prevent the cheetah from flourishing across two continents for thousands of years.
The cheetah likely evolved in Africa during the Miocene epoch (26 million to 7.5 million years ago), before migrating to Asia. Recent research has placed the last common ancestor of all existing populations as living in Asia 11 million years ago, which may lead to revision and refinement of existing ideas about cheetah evolution.


Cheetah at the Maasai Mara National Reserve
The now-extinct species include: Acinonyx pardinensis (Pliocene epoch), much larger than the modern cheetah and found in Europe, India, and China; Acinonyx intermedius (mid-Pleistocene period), found over the same range. The extinct genus Miracinonyx was extremely cheetah-like, but recent DNA analysis has shown that Miracinonyx inexpectatus, Miracinonyx studeri, and Miracinonyx trumani (early to late Pleistocene epoch), found in North America and called the "North American cheetah" are not true cheetahs, instead being close relatives to the cougar.
(Source: Wikipedia)

Thursday, August 2, 2012

Giraffe study


The giraffe (Giraffa camelopardalis) is an African even-toed ungulate mammal, the tallest living terrestrial animal and the largest ruminant. Its binomial name refers to its camel-like face and the patches of color on its fur. Its chief distinguishing characteristics are its extremely long neck and legs, its horn-like ossicones and its distinctive markings. It stands 5–6 m (16–20 ft) tall and has an average weight of 1,600 kg (3,500 lb) for males and 830 kg (1,800 lb) for females. It is classified under the family Giraffidae, along with its closest extant relative, the okapi. There are nine subspecies, which are distinguished by their coat patterns.
The giraffe's scattered range extends from Chad in the north to South Africa in the south, and from Niger in the west to Somalia in the east. Giraffes usually inhabit savannas, grasslands, and open woodlands. Their primary food source is acacia leaves, which they can browse at heights that most other herbivores cannot reach. Giraffes are preyed on by lions, and calves are also targeted by leopards, spotted hyenas and wild dogs. Adult giraffes do not have strong social bonds, though they do gather in loose aggregations if they happen to be moving in the same general direction. Males establish social hierarchies through "necking", which are combat bouts where the neck is used as a weapon. Dominant males gain mating access to females, who bear the sole responsibility for raising the young.
The giraffe has intrigued various cultures, both ancient and modern, for its peculiar appearance, and has often been featured in paintings, books and cartoons. It is classified by the International Union for Conservation of Nature (IUCN) as Least Concern, but has been extirpated from many parts of its former range, and some subspecies are classified as Endangered. Nevertheless, giraffes are still found in numerous national parks and game reserves.
(Source: Wikipedia)

Thursday, July 19, 2012

Ladybug study




The Coccinellidae are a family of beetles, known variously as ladybirds (UK, Ireland, Australia, Sri Lanka, Pakistan, South Africa, New Zealand, India, Malta, some parts of Canada and the US), or ladybugs (North America). When they need to use a common name, entomologists widely prefer the names ladybird beetles or lady beetles as these insects are not true bugs. Lesser-used names include God's cow, ladyclock, lady cow, and lady fly.

Coccinellids are small insects, ranging from 1 mm to 10 mm (0.04 to 0.4 inches), and are commonly yellow, orange, or scarlet with small black spots on their wing covers, with black legs, head and antennae. Such color patterns vary greatly however; for example, a minority of species, such as Vibidia duodecimguttata, a twelve-spotted species. has whitish spots on a brown background.

In some species the spots are so large that they merge, leaving the remaining bright colours as spots on a black background. Many coccinellid species are mostly, or entirely, black, grey, or brown and may be difficult for non-entomologists to recognize as coccinellids at all. Conversely, non-entomologists might easily mistake many other small beetles for coccinellids. For example the tortoise beetles, like the ladybird beetles, look similar because they are shaped so that they can cling to a flat surface so closely that ants and many other enemies cannot grip them.

Coccinellids are found worldwide, with over 5,000 species described, more than 450 native to North America alone.

The Coccinellidae are generally considered useful insects, because many species feed on aphids or scale insects, which are pests in gardens, agricultural fields, orchards, and similar places. However, some species do have unwelcome effects. Among these the most prominent are the subfamily Epilachninae, which are plant eaters. Usually Epilachninae are only mild agricultural pests, eating the leaves of grain, potatoes, beans and various other crops, but their numbers can increase explosively in years when their natural enemies are few, such as parasitoid wasps that attack their eggs. When that happens they can do major crop damage. They occur in practically all the major crop producing regions of temperate and tropical countries.

Coccinellids are typically predators of Hemiptera such as aphids and scale insects, though larvae and eggs of their own species can also be important resources when alternative prey are scarce.

Members of the subfamily Epilachninae are herbivores, and can be very destructive agricultural pests (e.g., the Mexican bean beetle). While predatory species are often used as biological control agents, introduced species of coccinellidae (such as Harmonia axyridis or Coccinella septempunctata in North America) out-compete and displace native coccinellids and become pests in their own right.

The main predators of coccinellids are usually birds, but they are also the prey of frogs, wasps, spiders, and dragonflies. The bright colours of many coccinellids discourage some potential predators from making a meal of them. This phenomenon is called aposematism and works because predators learn by experience to associate certain prey phenotypes with a bad taste. A further defense known as "Reflex bleeding" exists in which an alkaloid toxin is exuded through the joints of the exoskeleton, triggered by mechanical stimulation (such as by predator attack) in both larval and adult beetles, deterring feeding.

(Source: Wikipedia )

Sunday, July 15, 2012

Kingfisher study



Kingfishers are a group of small to medium sized brightly coloured birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species being found in the Old World and Australia. The group is treated either as a single family, Alcedinidae, or as a suborder Alcedines containing three families, Alcedinidae (river kingfishers), Halcyonidae (tree kingfishers), and Cerylidae (water kingfishers). There are roughly 90 species of kingfisher. All have large heads, long, sharp, pointed bills, short legs, and stubby tails. Most species have bright plumage with little differences between the sexes. Most species are tropical in distribution, and a slight majority are found only in forests. They consume a wide range of prey as well as fish, usually caught by swooping down from a perch. Like other members of their order they nest in cavities, usually tunnels dug into the natural or artificial banks in the ground. A few species, principally insular forms, are threatened with extinction.
The smallest species of kingfisher is the African Dwarf Kingfisher (Ispidina lecontei), which averages at 10.4 g and 10 cm (4 inches). The largest overall is the Giant Kingfisher (Megaceryle maxima), at an average of 355 g (13.5 oz) and 45 cm (18 inches). However, the familiar Australian kingfisher known as the Laughing Kookaburra (Dacelo novaeguineae) may be the heaviest species, since large individuals exceeding 450 g (1 lb) are not rare.
The plumage of most kingfishers is bright, with green and blue being the most common colours. The brightness of the colours is neither the product of iridescence (except in the American kingfishers) or pigments, but is instead caused by the structure of the feathers, which causes scattering of blue light (the Tyndall effect). In most species there are no differences between the sexes; when there are differences they are quite small (less than 10%).
The kingfishers have a long, dagger-like bill. The bill is usually longer and more compressed in species that hunt fish, and shorter and more broad in species that hunt prey off the ground. The largest and most atypical bill is that of the Shovel-billed Kookaburra, which is used to dig through the forest floor in search of prey. They generally have short legs, although species that feed on the ground have longer tarsi. Most species have four toes, three of which are forward pointing.
The irises of most species are dark brown. The kingfishers have excellent vision; they are capable of binocular vision and are thought in particular to have good colour vision. They have restricted movement of their eyes within the eye sockets, instead using head movements in order to track prey. In addition they are able to compensate for the refraction of water and reflection when hunting prey underwater, and are able to judge depth underwater accurately. They also have nictitating membranes that cover the eyes when they hit the water in order to protect them; in the Pied Kingfisher has a bony plate which slides across the eye when the bird hits the water.
(Source: Wikipedia)

Saturday, June 2, 2012

Praying mantis study

Mantodea (or mantises) is an order of insects that contains approximately 2,200 species in 15 families worldwide in temperate and tropical habitats. Most of the species are in the family Mantidae. Historically, the term mantid was used to refer to any member of the order because for most of the past century, only one family was recognized within the order; technically, however, the term only refers to this one family, meaning the species in the other 14 recently established families are not mantids, by definition (i.e., they are empusids, or hymenopodids, etc.), and the term "mantises" should be used when referring to the entire order.

A colloquial name for the order in the United States is "praying mantises", because of the typical "prayer-like" stance, although the eggcorn "preying mantis" is sometimes used since mantises are predatory. In Europe and other regions, however, the name "praying mantis" refers to only a single species, Mantis religiosa. The closest relatives of mantises are the orders Isoptera (termites) and Blattodea (cockroaches), and these three groups together are sometimes ranked as an order rather than a superorder. They are sometimes confused with phasmids (stick/leaf insects) and other elongated insects such as grasshoppers and crickets.

Mantises have two grasping, spiked forelegs ("raptorial legs") in which prey items are caught and held securely. Located at the base of the femur are a set of discoidal spines, usually four in number but ranging from zero to as many as five depending on the species. These spines are preceded by a number of tooth-like tubercles, which, along with a similar series of tubercles along the tibia and the apical claw near its tip, give the foreleg of the mantis its grasp on its prey. The foreleg ends in a delicate tarsus made of between four and five segments and ending in a two-toed claw with no arolium and used as a walking appendage.

The mantis thorax consist of a prothorax, a mesothorax, and a metathorax. In virtually all species the prothorax, to which are attached the head and forelegs, is much longer than the other two thoraces (the sole exceptions are the seven members of the Mantoididae family). The prothorax is also flexibly articulated, allowing for a wide range of movement of the front limbs while the remainder of the body remains more or less immobile.

The articulation of the head is also remarkably flexible, permitting nearly 300 degrees of movement in some species, allowing for a great range of vision (their compound eyes may contain up to 10,000 ommatidia and have a large binocular field of vision). The dark spot on each eye is a pseudopupil. As their hunting relies heavily on vision, they are primarily diurnal, but many species will fly at night, especially males in search of less-mobile females whom they can detect through pheromones. Flying at night allows these males to avoid many diurnal bird predators, and many mantises also have an auditory thoracic organ that assists them as they attempt to avoid capture by bats by detecting the presence of the bat's echolocation sounds and responding evasively.

Mantises have a wide range of wing morphologies and can be loosely categorized as being either macropterous (long-winged), brachypterous (short-winged), micropterous (vestigial-winged), or as apterous (wingless). If not wingless, a mantis will have two sets of wings: the outer wings, called the foreseeing or tegmina, are usually narrow, opaque, and leathery and function as camouflage and as a shield for the inner wings, or hindwings—it is this much more delicate, broad, and transparent set that is actually used for flight, though in many of the brachypterous species these wings are only capable of producing minimal and very temporary lift and in the micropterous species they have no flight-related function at all. Also, in many macropterous species, the female will have much shorter wings than the male and will only rarely take flight.

The abdomen of all mantises consist of ten tergites with a corresponding set of nine sternites visible in males and seven visible in females. The slim abdomen of most males allows them to take flight more easily while the thicker abdomen of the females houses the reproductive machinery for generating the ootheca. The abdomen of both sexes ends in a pair of cerci.
(Source:Wikipedia)

Tuesday, May 29, 2012

Turtle study


Turtles are reptiles of the order Testudines (the crown group of the superorder Chelonia), characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield. "Turtle" may either refer to the Testudines as a whole, or to particular Testudines which make up a form taxon that is not monophyletic.

The order Testudines includes both extant (living) and extinct species. The earliest known turtles date from 215 million years ago, making turtles one of the oldest reptile groups and a more ancient group than lizards, snakes and crocodiles. Of the many species alive today, some are highly endangered.

Like other reptiles, turtles are ectotherms—their internal temperature varies according to the ambient environment, commonly called cold-blooded. However, leatherback sea turtles have noticeably higher body temperature than surrounding water because of their high metabolic rate.

Like other amniotes (reptiles, dinosaurs, birds, and mammals), they breathe air and do not lay eggs underwater, although many species live in or around water. The largest turtles are aquatic.

The largest living chelonian is the leatherback sea turtle (Dermochelys coriacea), which reaches a shell length of 200 centimetres (6.6 ft) and can reach a weight of over 900 kilograms (2,000 lb). Freshwater turtles are generally smaller, but with the largest species, the Asian softshell turtle Pelochelys cantorii, a few individuals have been reported up to 200 centimetres (6.6 ft). This dwarfs even the better-known alligator snapping turtle, the largest chelonian in North America, which attains a shell length of up to 80 centimetres (2.6 ft) and weighs as much as 113.4 kilograms (250 lb). Giant tortoises of the genera Geochelone, Meiolania, and others were relatively widely distributed around the world into prehistoric times, and are known to have existed in North and South America, Australia, and Africa. They became extinct at the same time as the appearance of man, and it is assumed humans hunted them for food. The only surviving giant tortoises are on the Seychelles and Galápagos Islands, and can grow to over 130 centimetres (51 in) in length, and weigh about 300 kilograms (660 lb).

The largest ever chelonian was Archelon ischyros, a Late Cretaceous sea turtle known to have been up to 4.6 metres (15 ft) long.

The smallest turtle is the speckled padloper tortoise of South Africa. It measures no more than 8 centimetres (3.1 in) in length and weighs about 140 grams (4.9 oz). Two other species of small turtles are the American mud turtles and musk turtles that live in an area that ranges from Canada to South America. The shell length of many species in this group is less than 13 centimetres (5.1 in) in length.
(Source: Wikipedia)