Category Nature Science & Wildlife

          Some male and female birds of the same species have very different plumage, with the male usually being more brightly coloured to attract females. Other species show little or no difference between the sexes. As well as having different plumage, birds may make displays to each other during the breeding season. Some dance in elaborate curving patterns, spread their feathers and strut, or sing. Male birds may fight to defend their territories during nesting.

          Once a budgie is a few weeks old, you will be able to tell the sex of the bird by looking at its cere (the nose and nostril area). In normal circumstances, a hen’s is brown, and a cock’s is blue. The hen’s cere becomes enlarged and scaly during the breeding season, and the male’s becomes a darker shade of blue. Simple!

          But there are a few complications. Hens sometimes have a light blue cere, when their breeding hormone levels are low. It will also be this colour, or white with just a hint of blue, if the bird is ill. In the wild the female’s cere is light blue, turning brown during the nesting season. In young hens, the cere is a light blue with white around the nostrils.

          Cock birds, although nearly always sporting a blue cere, may have a brown or brownish-pink one if his breeding hormones dip, or if he is ill. An ill male may develop a yellow-greenish tinge around the nostrils too. In immature cock budgies the cere is a blueish pink or light purple.

          Some budgie types are harder to sex. Albino, Lutino and Mottled birds, for example, have off-white, light pink or bluish pink ceres, and males of some of the pied varieties have light pink, blueish pink or white ones. With hundreds of variations on the basic types mentioned in the Budgie types section , there is always a chance that your bird will have an ‘ambiguous’ cere colour. In 90% of cases, however, the brown-or-blue rule applies.

          In spite of these complications, cere colour is still the easiest way of sexing budgies. There are a few gender-related differences in voice and behaviour, too; but these are not as consistently ‘male’ and ‘female’ as cere colour. If you inherit an adult bird of unknown sex and with an ambiguous cere, watch out for bonding behaviour – any excessive head-bobbing is likely to be a male and any excessive squawking, rather than chirruping and singing, is probably female.

          Many snakes throw themselves along the ground in waves that pass from head to tail. They have hundreds of pairs of ribs and strong muscles to enable them to do this, while their scales grip the ground. North American sidewinders, however, move as their name suggests, by throwing their coils sideways along the ground. Snakes have four ways of moving around.  Since they don’t have legs they use their muscles and their scales to do the “walking”.

Serpentine method:  This motion is what most people think of when they think of snakes.  Snakes will push off of any bump or other surface, rocks, trees, etc., to get going.  They move in a wavy motion.  They would not be able to move over slick surfaces like glass at all.  This movement is also known as lateral undulation.

Concertina method:  This is a more difficult way for the snake to move but is effective in tight spaces.  The snake braces the back portion of their body while pushing and extending the front portion.  Then the snake drops the front portion of their body and straightens a pulls the back portion along.  It is almost like they through themselves forward.

Sidewinding: This is a difficult motion to describe but it is often used by snakes to move on loose or slippery surfaces like sand or mud.  The snake appears to throw its head forward and the rest of its body follows while the head is thrown forward again.  (See picture.) 

Rectilinear Method:  This is a slow, creeping, straight movement.  The snake uses some of the wide scales on its belly to grip the ground while pushing forward with the others.

Picture Credit : Google

          It is likely that birds evolved from reptiles. Like reptiles but unlike most mammals, they lay eggs that hatch outside the mother. All adult birds have feathers, rather than fur or scales, and most can fly. However, birds are similar to mammals in being warsm blooded.

          When one thinks of the differences between mammals and birds, the first thing that comes to mind is that mammals give birth to their young whereas birds lay eggs. Now let us look at other differences between mammals and birds. The birds have feathers whereas mammals have only fur or hair. This feature is one of the main features of birds that differentiate them from mammals. Birds use feathers for controlling body temperature, flying, and attracting the opposite sex.

          As birds need to fly, they have porous or hollow bones. In contrast, mammals have denser bones. Birds have wings although mammals have paws, hands, and hooves. There is also a difference in the feeding of the young. Mammals feed their young milk produced by the mammary glands. On the other hand, young birds are fed by the parents regurgitating partially digested food.

          Birds and mammals have a larynx. The mammals produce sounds using the larynx. In birds, this organ does not produce sounds. Instead of using the larynx for sound, birds have a syrinx which serves as a voice box. The lungs of birds do not expand or contract as that of the lungs of mammals. In mammals, the oxygen and carbon dioxide is exchanged in the alveoli which are microscopic sacs in the lungs. In birds, the exchange happens in air capillaries which are walls of microscopic tubules. While there is only a single respiratory cycle in mammals, there are two cycles in birds.

          Now comparing the blood, birds have a nucleus in the RBS whereas it is not generally seen in mammals. If there is a nucleus in the RBS in mammals, then it is a sign of sickness. The RBS of birds are oval in shape whereas most of the mammals’ RBSs have a round shape.

Picture Credit : Google

          The chameleon is able to change colour to match its surroundings by releasing or tightening special cells on its skin. As well as this remarkable ability, chameleons are amazing in other ways. They are able to grip very strongly with their toes and tails to balance on precarious branches. Their extraordinary tongues, which are able to shoot out as far as the chameleon’s body length, are sticky and able to scoop back prey like a piece of elastic. Finally, the chameleon’s eyes are bulging and can move in any direction, protected by an eyelid that is fused all-round the eye, leaving only a tiny hole in the middle. Even stranger, the chameleon can move each of its eyes in a different direction at the same time!

          Chameleons are famous for their quick color-changing abilities. It’s a common misconception that they do this to camouflage themselves against a background. In fact, chameleons mostly change color to regulate their temperatures or to signal their intentions to other chameleons. Since chameleons can’t generate their own body heat, changing the color of their skin is a way to maintain a favorable body temperature. A cold chameleon may become dark to absorb more heat, whereas a hotter chameleon may turn pale to reflect the sun’s heat.

          Chameleons will also use bold color changes to communicate. Males become bright to signal their dominance and turn dark in aggressive encounters. Females can let males know if they’re willing to mate by changing the color of their skin. Owners of chameleons can learn to read their pet’s mood based on the color of its skin.

          So how do they pull off these colorful changes? The outermost layer of the chameleon’s skin is transparent. Beneath this are several more layers of skin that contain specialized cells called chromatophores. The chromatophores at each level are filled with sacs of different kinds of pigment. The deepest layer contains melanophores, which are filled with brown melanin (the same pigment that gives human skin its many shades). Atop that layer are cells called iridophores, which have a blue pigment that reflects blue and white light. Layered on top of those cells are the xanthophores and erythrophores, which contain yellow and red pigments, respectively.

          Normally, the pigments are locked away inside tiny sacs within the cells. But when a chameleon experiences changes in body temperature or mood, its nervous system tells specific chromatophores to expand or contract. This changes the color of the cell. By varying the activity of the different chromatophores in all the layers of the skin, the chameleon can produce a whole variety of colors and patterns.

          For instance, an excited chameleon might turn red by fully expanding all his erythrophores, blocking out the other colors beneath them. A calm chameleon, on the other hand, might turn green by contracting his erythrophores and allowing some of the blue-reflected light from his iridophores to mix with his layer of somewhat contracted yellow xanthophores.

          With these layers of cells, some chameleons are capable of producing a dazzling array of reds, pinks, yellows, blues, greens, and browns. These bold statements won’t help them blend into the background, but they will allow them to get their message across to other chameleons loud and clear.

Picture Credit : Google

          Both crocodiles and alligators spend most of their lives in swamps and rivers in warm climates, although they breathe air through nostrils on the top of their snouts, closing these off when they dive. Caymans and gavials are relatives of crocodiles and alligators. The simple way of telling them apart is that crocodiles show the fourth tooth in their lower jaw when their mouths are closed, while alligators do not. It is probably not wise to go near enough to a live crocodilian to find out, however, as they have been known to attack humans!

          Coming face to face with a crocodile or an alligator, you’d see a mouth full of serrated teeth that would likely scare the bejeezus out of you. The two reptile groups are close relatives, so their physical similarities are expected. Upon closer inspection, not recommended out in the wild, you’d spot glaring differences:

          Snout shape: Alligators have wider, U-shaped snouts, while crocodile front ends are more pointed and V-shaped. Toothy grin: When their snouts are shut, crocodiles look like they’re flashing a toothy grin, as the fourth tooth on each side of the lower jaw sticks up over the upper lip. For alligators, the upper jaw is wider than the lower one, so when they close their mouths, all their teeth are hidden.

          Home base: Crocodiles tend to live in saltwater habitats, while alligators hang out in freshwater marshes and lakes. They belong to the subgroup Eusuchia, which includes about 22 species divided into three families: the fish-eating gavials or gharials, which belong to the Gavialidae; today’s crocodiles or the Crocodylidae; and the Alligatoridae, or alligators. Eusuchians appeared on the scene during the late Cretaceous some 100 million or so years ago.

Picture Credit : Google

          Reptiles are cold blooded, so must gain warmth from their surroundings. This means that they can be found anywhere except in the very coldest regions of the Earth. Those that live in cooler areas usually spend the winter hibernating. Most reptiles lay eggs with hard or leathery shells. Their young hatch into miniature versions of their parents, but as reptiles can continue to grow after they are mature, some reach an enormous size.

          The term “reptile” is derived from a Latin word meaning “creeping animals.” These animals include snakes, lizards, crocodiles, caimans, alligators, turtles, geckos, and chameleons, with lizards and snakes species making up the majority of all reptiles. Reptiles are cold-blooded animals which mean they are unable to regulate their own body temperature. The first reptiles evolved approximately 320 million years ago from the advanced four-limbed vertebrates known as reptiliomorph. These early reptiles became adapted to life on dry land. Reptiles have diverse ways of defending themselves from danger including biting, hissing, camouflaging, and avoidance. This article focuses on some of the most outstanding characteristics of reptiles.

          Most reptiles reproduce sexually while others are capable of reproducing asexually. The reproduction activities take place through the cloaca located at the base of the tail. Copulatory organs can be seen in most reptiles which are often stored inside their bodies. Male turtles and crocodiles have a penis while lizards and snakes have a pair of hemipenes. Other species like the tuatara do not have copulatory organs hence mating is through the pressing together of the cloaca. After successful copulation, the female reptile lays eggs which are covered with a shell. The eggshell protects and keeps the embryo from drying out and allows for the exchange of gasses. The egg contains chorion which aids in gaseous exchange, the albumen which is a reservoir for protein and water, and the amniotic fluid which protects embryo and aids in osmoregulation. Some reptiles incubate the eggs by laying on them while others bury them in the sand until they hatch.

          Most reptiles are cold-blooded vertebrates. They do not have the psychological means of regulating their body temperatures and have to depend on the external environment. Other species exhibit a mix of ectothermy, poikilothermy, and brandymetabolism. Reptiles often bask in the sun or hibernate during cold seasons to raise their body temperatures. When the sun is too hot, they will retreat to shady areas or inside the water to cool or lower their body temperatures. Because reptiles have unstable body temperature, their metabolism requires enzymes that are capable of maintaining efficiency over a range of temperatures. It is assumed that reptiles cannot produce enough energy required for long-distance chase like the warm-blooded animals. However, it remains unclear as to whether their cold-bloodedness is as a result of their ecology or not.

          Reptiles have either four legs, or some like snakes, are descendants of four-limbed ancestors. In most snakes, all traces of legs including bones for the legs have disappeared. However, they still remain successful predators even without the legs. Snakes have three ways of moving on land; straight crawling, lateral undulating, and sidewinding. Although lizards have four limbs, most lizards have an alternating gait which limits their endurance. The tail of some lizards is prehensile and can assist them in climbing. Some reptiles like crocodiles have claws on their feet. These claws assist in movement and hunting.

          Reptiles exhibit similar characteristics of other vertebrates like mammals, birds, and some amphibians. They have backbones that house the spinal cords that run the length of their bodies. Reptiles also have chains of bony elements from the tail to the head. The bony endoskeleton consists of cranium or skull, appendages, and limb girdles. The endoskeleton protects the inner tissue and also aids in body movement. Skeletons differ from one species to another, with crocodiles having some of the largest body structures in this class.