CROP CIRCLE

One can ask a question like, what is a crop circles?. It is easy to understand what crop circles are. According to the knowledge I have, after reading different materials and viewing videos. Crop circles are defined as a place of similar crops that have systematically geometric patterns. It is not easy to explain the pattern of crop circles that are found in fields. Some scientists said that, crop circles are just circles that are found in crops. Some of them said that, a circle is a symbol of humanity on earth. They also said that, it is a symbol of God and Heaven in different things. Crop circles are mostly found in wheat, corn, seeds, maize, oats and in barley. Sometimes Crop circles may occur in snow and even in long grass. Some say the crop circles are man made while others are artificial. Some of the Scientists said that, most of the crop circles are created at night and early in the morning between 11pm to 4 am.


There are different shapes of crop circles; some are like a ring, flattened, rectangular, geometric, triangle, and circular shapes.. In place where there is crop circles plants are bent above the soil and it laid down like a geometrically patterns. If we look on this grass, it is invisible to see the physical sign indicating the damage between those plants. But there is some heat in those plants because of light burn that occurs in the base of stems. Depletion of local watershed occurs but you can not see it physically. This will cause the crops (maize) to change the colours. Although crop circles does not happened to trees.


According to the laboratory results found in the United Kingdom. The research is based on barley of crop circles. They focus on barley (Samples of seeds heads). This was done on 07 November 1992. The shape of these crop circles is circular in shape and it was fourth circles. The people who study this crop circles said that, there is different between the seeds from the circles and the seeds that are outside the circles and they grow differently. The different is that, seeds that are found outside the circles are well-developed while in the inside of the circles have no seeds.

Another laboratory report which is also found in United Kingdom. Were focused on seeds. The information indicates that, there are 21m circles that are formed during the night of April 24-25 1992 and they are collected on 01 May 1992. The shape of these crop circles is circular in shape. They provide information that, the cells at outer circles were the same as compared to those in the circles. This is when they focus on the stem of the plants

Soil samples taken within the crop circles have been studied and the results show that, they contain Radioactive which is not occur in the outside the circles. During watching the videos, the type of crop circles that attract my heart was Triple Julia set because it has beautiful shape and it consists of 35 circles.

Reference

1. Wikipedia Contributors. Plagiarisms [Internet]. Wikipedia, The Free Encyclopaedia, 2006 May 26 00:36 Available from: http://en.wikipedia.org/wiki/Crop_circles
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ORDER OF PLACENTALMAMMALS AND LISTS OF MAMMALS REPRESENTING EACH ORDER

Placental mammals contain different types of orders. These orders include: chiroptera, pholidota, carnivore, perissodactyla and artiodactyla. Each order consists of different animals. These animals hold their young within the mother until development is well along. The eggs contain little yolk, but the extra embryonic membranes form an umbilical cord and placenta.

Order pholidota

The name means scaly ones. The major diagnostic characteristics are the scales that cover their bodies. It had mode of keratinized epidermis. According to the behaviour and ecology of this order, some are terrestrial where as some are arboreal. Arboreal ones have prehensile tails and the terrestrial ones have short tail. These small orders consist of some very unusual animals known as Pangolins.

Pangolins are small group of mammals that feed mostly on aunts. Pangolins lack teeth. Pangolins have long tongues that are used to capture ants, termites and their main food. Pangolins have power legs which are used for digging on hard ground. The front claws of pangolin are long. It had large tail but short legs with sharp claws. New born of pangolins are razor sharp. The skull of pangolins is smoothly conical. The palate is long in pangolins. They have no jugal and the zygomatic arch is incomplete. Pangolins mandible is narrow and weak. The pyloric part of stomach is thickened and muscular.

Order chiroptera

These are only mammals that are truly fly and well furred bodies, membrane naked-transparent. Animal that fall under this order have very poor vision and use echolocation to find prey and navigate. Most of these animals are active from dusk to dawn known as nocturnal. This orders it consist of animals known as bats.

Bats are mammals found in order chiroptera. Bats have true power wings. Their forelimbs are developed as wings making them capable to flight. Their hind limbs are variously specialised but generally weak. Their incisors are generally reduced. The length of head and body ranges from 3 to 40cm. The finger bones of bats are more flexible because cartilage in their fingers lacks calcium and other minerals near the tip. The skin on their wings membranes is more elastic and can stretch more. Bats are fall under the nocturnal group, and use echolocation to navigate at night and find food. Their eyes are small and inefficient. Their ears are usually well developed. Bats have tail membrane that is used like rudder when flying.

Order carnivore

Carnivores are strictly meat eaters. Carnivores are large in size. They all have hair. Many are nocturnal. The teeth are well developed. All carnivores have sharp canines teeth. All carnivores have strong claws and chest muscles. They have 4 to 5 digits on each leg or arm. Most of carnivores have relatively large brains. Dogs, cats, lion, walrus and sea lion are examples of carnivores. Now let’s look at animal called walrus.

The skin of walrus is pink or red in colour. The face and body are covered by short hair that are reddish brown or pink on bulls and brown on cows. Walrus are heavily built with fat body. The features of the head are squarish snout. The eyes are small and ears are internal.

Order perissodactyla

Perissodactyla are small orders of herbivores consisting of herbivores, horses and tapirs. This order contains animals that are not considered as relatives to the horse. The name Perissodactyla means odd-toed. All perissodactyla are large animals. Their cheek teeth are massive, strong and modified for grinding.
Animal fall under this order have complete set of incisors. And elongate skull. These animals do not have true horns

Order Artiodactyla

The order artiodactyla includes deep, pigs, cattle, goats, giraffe, camels and sheep. The toes are covered by large honey hooves. Artiodactalya all have long limbs. Many Artiodactalya have horns or antler that grows from frontal bones of their skull. All Artiodactalya are carnivores. Let’s look at giraffe as an example; it is the tallest animal in the world. The front leg of the giraffe is longer than the back legs. They also posses long neck. The whole body of giraffe is covered with a spots.

Cetaceans

Cetaceans include the blue whale, the dolphins and the porpoises. They are mammals which are warm blooded animals, they have few hairs on their bodies, and they spend their whole life in water. All porpoises and dolphins as well as minke whale are baleen whales. The body of dolphins consists of the following parts, dorsal fin tail fluke, pectoral flipper, eye and blowhole. The organism which belong to the order called cetacean usually have the following characteristics, large body size, bubbler, usually hairless, sensory abilities such as large brain and they are good in swimming.


Reference

Wikipedia contributors. Mammal [Internet]. Wikipedia, the free enclyclopedia, 00:51, 10 May 2006UTC[Cited 12 May, 2006, 5:25] Available from http://en.wikipedia.org/wiki/Mammals

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BIRDS ARE CLOSELY RELATED TO DINOSAURS

Dinosaurs are the vertebrates’ animals. Birds are the closest-living relatives of dinosaurs. Bone tissue of Dinosaurs are similar to that inside of the of females birds.
The reproductions of dinosaurs are very closely related to birds. Dinosaurs produced and shell their eggs like modern birds.
The evidence of dinosaurs and birds are related. The discovery of pigeon-size fossils called archaeopteryx had a bird like skull, perch feet, and was a powered flyer with wings of the basic pattern and proportions of the modern avian wing. Dinosaurs have also the identical feathers to modern flying birds.
Some scientist call a small creature named mononykus as a new link between birds and dinosaurs, because it shares some features with modern birds, such as keeled sternum and some fused wrist.

The footprints of dinosaurs tell us that many of them walked upright which is similar to modern birds. The earliest dinosaurs were light carnivores, omnivores and were small. It is now believed that the ancestors of birds are theropod dinosaurs. Archaeopteryx, found in Jurassic rocks of Germany, has feathers and wishbone, still go to reptiles like features such as teeth, long tail and forelimb structure. This characteristics is resembles a small theropod dinosaurs. The evidence supports the hypothesis is that, birds evolved from dinosaurs.

Another bird fossil of Archaeopteryx was discovered in Northern side of china and was named as a confuciusornis. This new evidence of fossil was resembles Archaeopteryx with having wings claws, but unlike Archaeopteryx and like modern birds and it confuse, because it indicates, lacked teeth and making it birds like than Archaeopteryx. Both of these fossils were look like birds and dinosaurs. Probably it can fly but not modern birds due to their reptiles’ feathers.

Scientist described the fossil protoavis as true birds which is closer to modern birds than Archaeopteryx. The evidence also shows that, the first birds lived at the same time as earliest dinosaurs. This could force the modification of theory that, birds and dinosaurs are the same. Dinosaurs and birds are looked like, not because they were closely related, but because they lived in similar environment and they survive in a similar way. The discovery of confuciusornis show us that, fossil of the same age as Archaeopteryx has given us more evidence on the evolution of birds and their link to dinosaurs. It is commonly thought by scientist, that birds evolved from dinosaurs, and more from theropod dinosaurs.

Scientist from china has discovered the remains fossil of four winged dinosaurs, with modern feathers on both forelimbs and hind limbs. The new species micro raptor gui, provide evidence that birds evolved from dinosaurs. Within the theropod group, birds are most closely related to cromaeossaurids. Dinosaurs took care of their eggs much like birds do. They layed them in mass breeding ground and watched over them after they hatched.

Legs of dinosaurs tend to develop towards the bird structure, and the development is not harmonious and toes are bird-like. The pelvic bones of bird always consolidated those of dinosaurs.


Reference

Ambeliz, R. 2002. Birds and Dinosaurs. [Online]. Available from: http://geology.wcedu.pima.edu/~rambeliz/rafweb.htm%20[2006, May 11]

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THE DIFFERENT BETWEEN NEW WORLD MONKEY AND OLD WORLD MONKEY

Monkeys are arranged into two main groups. New world monkeys are known as platyrrhines which are related to apes and humans. They are only found in South America. The new world monkey nostrils are wide septum and nostrils faced outwards, but old world monkeys have narrow septum and their nostrils face forward. New world monkey are small to medium. The new world monkeys have 3 premolars while the old world monkey has 2 molars. Old word monkeys are known as catarrhines. They are only found throughout tropical Africa and Asia. All new world monkeys differ slightly from old new world monkeys in many aspects but the most prominent is nose.


Platyrrhines and catarrhine differ in shape of the nose. New world monkeys have flat nose. The nostrils are far apart and open to the side while in the old world monkey, nostrils are closer together and open downward or forward and had also dawn facing nose. The world monkey has big, sharp canines with a distena (gap between canines and incisors) and the upper canines are kept sharp by being honed. Old world monkeys have larger average than new world monkey. For examples males baboons are the biggest old world monkey. Catarrhines are more terrestrial and they share their habitats with prosiams and apes.


According to the hands of new world monkey, thumb lies in line with other digits. Spider monkey has lost their thumbs. Some species have fingernails on big toe. Where as in the old world monkey, thumbs are rotated and more opposable like human langurs, and baboons. The finger nails and toenails are present on all digits. In the new world monkey, they have 3 premolars rather than two premolars. Molars are relatively large in the new world monkeys and the last molars are relative small and sometimes absent. In the old world monkey they have two premolars. Premolars in the mandible are sectorial. That is, it is specialised for sharpening the upper canine. Molars have sharply connected cups


The ear regions of new world monkey, tympanic membrane are connected to external ear by a bony ring while in the old world monkeys, tympanic membrane are connected to external near by a bony tube. In the new world monkey some species have pensile tails while in the old world monkey all have tails but lack of prehensility feature. Few species in the new world monkey have one male multifemale group like many of the old world monkey species. New world monkey have scent glands rely more on scent to mark territories than old world monkey.


New world monkey confined to arboreal habitats and rely heavily on fruit and less on foliage with compare to old world monkeys. Old world monkeys spend some or most of the day on the ground and they tolerate in a wider range of habitats from rainforest through savannah fringe. Most of the new world monkeys are closely related. Cebidae and Atelidae families are found under new world monkey. Cidibae include animas like, squirrel, capuchin, owl and monkeys. Atelidae include animals like spider and howler monkeys.

Reference

Wikipedia Contributor Monkeys (internet) Wikipedia, the free Encyclopedia, 2006 May 12, 17:33 UTC [Cited 2006, May 12, 17:25] Available from: http://en.wikipedia.org/wiki/Monkeys

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ECHOLOCATION IN BATS AND WHALES

Echolocation is the ability to see through sound. Echolocation is the use of ultra-high frequency sound for navigation. To understand how echolocation works, imagine an echo-canyon. If you stand on the edge of a canyon and shout hello you will hear your own voice coming back to you an instant later. Animals that use echolocation emit calls out to the environment. Echolocation is the method of sensory perception by which animals familiarize themselves to their surroundings, detect obstacles, and communicate with others. They use echoes to locate, range and identify the objects. Echolocation is used for foraging in various environments. Bats and whales are good examples of echolocation.

Most bats use echolocation or sound to find their food and navigate in the dark. Bats emitted high sound. Bats send out high frequency and listen for the echoes to locate their prey. Bats send out sound waves using their mouth or nose. When sound hits, an object echo comes back. The bat can identify an object by the sound of the echo. Most bats see pretty well. Echolocation help them to find their prey in the dark, most bat species have developed a navigation called echolocation. Bats are not blind they can also see in the dark by listening to the echoes of their high frequency calls, with this system they can pick up insects as tiny as mosquitoes. Bats that eat frogs, fish and insects use echolocation to find their prey in near darkness after emitting a sound, these bats can tell the distance, direction, size, surface texture and material of an object from information in the retaining echo.

Humans can not high pitched sounds that bats make. Most fruit bats use eyesight and smell for finding food not echolocation. When thousands of bats flying out of cave, they can use their echolocation of noise around. Different species of bats use different patterns of echolocation frequencies to find food and navigate. Whales is an another examples of echolocation.

Whales are large, and are aquatic mammals. Toothed whales produced sounds to communicate and echolocate. The whales send out a ray of sound. When the sound of echo came back. The sounds are picked up by the lower jaws. The lower jawbones are empty and filled with fat. These help the sound travel through the jawbone up to middle ear, inner ear and auditory nerve. The echoes are interpreted by the brain. Toothed whales use echolocation to sense objects. High-pitched sound is sent out by whales. The sound bounches off the object and some returns to the whale. The interpret this returning echo to determine the object shapes, direction, distance and texture.

Some whales may not use echolocation but may find their prey simply by listening. Toothed whales prey on fish, squid or marine mammals using echolocation. Echolocation helps an animal to navigate in water. The highest sound produces a more detailed of an object because the sound wave is shorter. A lower sound travels into water because the wave’s length is longer and can be used to detect distance or larger objects. Water is an excellent sound transmitter. Whales have capitalized on this water to compensate for reduced visions in cloudy water of the sea.

References

Roth, J. 2006. Echolocation. [Online]. Available: http://www.eparks.org/wildlife_protection/wildlife_facts/bats/echolocation.asp [2006, May 14]

Max, J. 1995. Fishin for facts: Echolocation. [Online]. Available: http://www.whaletimes.org/echolocation.htm [2006, May 14]
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COMPARISM BETWEEN THE PLACENTAL AND MARSUPIALS MODES OF REPRODUCTION

There are huge differences between the marsupials and placental mammals. The different between marsupials and placental mammals is that their mode of reproduction differs in the gestation period. Marsupials are subdivision of mammals’ with several characteristics, and they have very short gestation whereas the placental have usually longer gestation. The neonate are incompletely developed in marsupials where as neonate are anatomically complete in the placental. In addition, the reproductive tracts of marsupials in the females are fully doubled. Nevertheless, the right and left vagina do not combine to form a single body as they do in placental mammals. Thus, in the marsupial’s mammals, birth takes place through new canal, pseudovaginal canal.

The longer gestation period in the placental mammals that occurs in the offspring that are born, are fully developed. The mature time in placenta compared to other vertebrates depends on placenta, which allows nutrients to move from mother system to embryo. The mother and embryo do not share the same blood supply, but the placenta is richly supplied with blood vessels, nutrients metabolites pass through and prevent the transfer of immunity system. In Marsupials pregnacy does not break the continuance of the next oestrus cycle, because it is not in the placenta. Birth in marsupials occurs much earlier as opposed to the placenta mammals. The fetus to the pouch becomes attached to teat just for a weeks or a months. This depends on the type of species, but marsupials spend 12 days in the reproductive tract.

Marsupials and placental birth may not equal. The placenta is beneficial and it allows organism to replace its marsupial counterpart if it introduce in the same area. Gestation length indicates the direct exchange between advantageous for child as is not like to the mothers. Marsupials’ reproduction is more beneficial, by reducing the death especially related to child mother union. The length and time of marsupials’ gestation are important through the evolutionary genetic recombination. The young placenta mammals spend long time to develop inside the mother body before birth.

The development of marsupial embryo, the arrangement of ducts that become the female reproductive tract differs from the placental. The placental mammals have penis, which look like the female vagina, whereas the marsupial’s males have a forked, and scrotum penis in the front. As for instance, wolf animals have many marsupials that are essentially identicall to the placental mammals. Marsupial and placental mammals have evolved coincidently as a results of common environmental exposures. The hands indicates that, each marsupial is unique kind from their placental twin.

Just to conclude, marsupials birth takes place through a median canal. Its marsupium is used for nursing young, but this, does not happen in all the marsupials species. On the other hand, the placental species has no marsupium. Some marsupials have chorioallantoic placenta, with no villi, while in the placenta have extensitve villi. Left and right vaginae and uteri of marsupials do not fused to form a single body, where as left and right vaginae of placental is fused. Penis in placenta is not forked, scrotum lies in the posterior of the penis. According to the degree and development of young in placental, gestation period is long and the young are born with functional organs and have short lactation period where as in the placental mammals lactation period is prolonged . In marsupials degree of development the young have short gestation, which can takes 8 to 43 days depending on species. Development takes place in pouch.

Reference

Wikipedia Contributors. Marsupials evolution[Internet]. Wikipidia, The free encyclopedia, 2006 May, 10, 04:55 UTC [cited-2006 May, 12]. Availabe from:
http://www.nwcreation.net/wiki/index.php?title=Main_Page

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EVIDENCE SHOW DINOSAURS WERE WARM-BLOODED ANIMALS


Warm blooded animals generate heat internally and maintain a constant temperature. Examples are birds, and mammals. Dinosaur bones are reaching in Halversian canals that support nutrients and load blood to the cells and lay down new bone. The fast growing bones of warm blooded animals have the same high density of Halversian canals while the slow growing bones cold blooded reptiles have fewer. Warm blooded animals have highly vascularized bone tissues.


Evidence of indicates that Dinosaurs have highly vascularized bone. Moderm warm blooded animals have more erect deportment than cold blooded animals. Most dinosaurs have erect attitude then it indicates they had highly activity levels and were warm blooded animals. Some evidence suggests that sauropods were cold blooded, this convincing case indicate that, some of small carnivorous dinosaurs were warm blooded. We know that, birds are warm blooded animals. Most dinosaurs had similar behaviour of birds which is warm blooded animals; it means dinosaurs are warm blooded animals.


Richard Owen is the one who named the dinosaurs. He said that, dinosaurs were version of reptiles that were very active and perhaps warm blooded animals and even though scientist who followed Owen classified dinosaurs’ behaviour as a lizard.
Ostrom with the scientist called Robert Barker start to argue that dinosaurs were more active. Ostrom, Bakker and other scientist keep saying that, dinosaurs were more closely related to birds than reptiles. Because birds are warm blooded animals why not dinosaurs. It means the dinosaurs are warm blooded.
Assessment of dinosaurs fossils propose that, dinosaurs were warming blooded. Even the remains of microscopic holes in the bones indicate tiny blood vessels had trapped by fast growing bone tissues. Scientist reasoned said, any animal that growing faster must be warm blooded animal.


By the time of Triassic, dinosaurs thought the role of predators and herbivores and all other roles down to very small, which left to mammals and other reptiles. How do they take over in the first place, and keep the mammals different for so long if the mammals had potent evolutionary advantage in being warm blooded? Those who believe that dinosaurs are large reptile, it is an unacceptable view. The bones and footprints can produce the evidence that support dinosaurs are warm blooded animals. Bones of all types of dinosaurs have now studied. It has vascular canals equivalent to those of birds, it has generally poor growing but more obvious in teeth, woven bone evidence show typically of rapid bone growth. Because of this evidence it shows us that they resemble warm blooded rather than cold blooded animals.


The life style of smaller agile dinosaurs support that, they are warm blooded animals, whereas modern cold blooded reptiles are sit and wait for hunters , predatory dinosaurs were active in follow and attacking their pray. Insulation rises with regards to body temperature. Because of the supposed problem insulin would cause an animal whose temperature depends on external environment. It would seem counter productive for cold blooded animals to be insulated, and they appear to be lost example of such situation, whereas warm blooded animals have some form of insulation. This is the strong evidence discovery of insulated dinosaurs that give a clue that dinosaurs are warm blooded animals.

Reference

Beverly, E. 2000. Dinosaurs v.s. Warm-blooded?. [Online]. Available: http://www.priweb.org/ed/ICTHOL/ICTHOL04papers/13.htm [2006, May 10]
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DISCUSS THE PROCESS OF FOSSILIZATION AND ITS SIGNIFICANCE IN THE INTERPRETATION OF EVOLUTIONARY EVENTS.

Fossilization is the process of change of matters into fossils. Fossils are the remains of animals, plants and organisms. They are many types of fossils which occur as result of different types of fossilization process. Fossil come in many different ways. They are different types of fossils and fossilization process fossils Each type of fossil is occurs as a results of different fossilization process and each tells scientist something about material conserve. Fossils consist of traces of remains of organism and mark left behind the organism while it was alive. E.g. footprint, trackways, bites marks and dwelling burrows. Fossilization is rare occurrence because most of the components of living things tend to decompose. Organism to be fossilized, the remains needs to be covered by sediments.

The term fossilization does not only refer to the remains of organism but also to the impressions in rock and traits form by organism when they are alive. Fossils are formed when living organism dies and the part of the body are kept safe. Burial prevents the destruction of organism by scavenger, bacteria or weathering and erosion. It is also important because oxygen is no longer available to bacteria that cause the decay. Fossilization favours the following organism: big organism with hard body parts, organisms that were widespread and organism that lived for a long time. It favours these because it is impossible to find the following: small fossils, soft bodied organism living in small areas that did not live for a long time, either because they become extinct or because they evolved quickly. Geological process such as erosion destroys many fossils.

Fossilization process start when living thing dies, flow down a river and lodges on a sandbar. The bone may get covered by mud or sand but the tissue and skin decomposed. In drier areas, animals may fall into a crack and be quickly covered by wind blown sand. Once burial has occurred the remaining process of fossilization can continue. During the period of some hundreds millions years sediments built up over the buried remains and the pressure drives water out and converts the sediments to rock.
During the life time of rock, water sort through it dissolves some minerals and deposit them at the other sites, and deposits different minerals at the original site of the fossil thus cause the fossil remains themselves become converted into different types of rock
The process of carbonization occurred in the process of fossilization, plant leaves, and some body parts of fish, and reptiles decompose going behind only the carbon. This carbon creates the idea in the rock giving the great details of fossil. Plants are commonly fossilised through carbonisation

Fossils are the main sources of information on the evolution. Without the information provide by fossil, we can not have no direct knowledge of timing of biological events such as the following: origin of life, the development of skeletons, the colonisation of the land, the appearance of mammals and the flowering plants, the development of flight and the major episode of extinction.

Fossils are the main source of information because it gives the history development and the evolutionary relationships of Morden flora and fauna. It also gives the knowledge and characteristics of extinct organism such as dinosaurs

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HOW THE FIRST PLANTS AND ANIMALS EVOLVED AND BECAME DEPENDANT ON EACH OTHER


Plants take carbon dioxide and release oxygen in the process of photosynthesis, photosynthesis; animals inhale oxygen and exhale carbon dioxide in the process of breathing. Plants play an important role in the nature cycle. Without plants there would be no life on earth. Plants are the only organism that can make their own food. We breathe oxygen from plants. The quality of air is influenced by plants because plants can stop the movements of dust and pollutants. Through the intake of carbon dioxide plants reduce the greenhouse effect effect which comes from the burning of fossils fuels.

The first animals to evolve are called multicelled Eukaryotic animals. These evolved from colonies of single celled organisms. During this time animals were small and simple but evolved into all larger and more complex animals. The first fish evolved and the oceans were dominated by different types of invertebrates.

2, 5 million years ago, the earth and atmosphere were stable enough to support primitive life. Single celled organisms developed. The first plants to evolve were Blue-green Algae. Blue-Green Algae used sunlight and water to make food, and in the process, created oxygen. Blue-Green Algae grew in the earth seas and they began to fill the atmosphere with oxygen which made it possible for other organism to develop. Plants are the only organisms that can make their own food but animals can not makable to make their own food and they depend directly or indirectly on plants for their supply of food. All animals and the foods they eat can be traced back to plants.

Plants and animals are made by many types of cells. Plants have thick and rigid walls that consist of cellulose where as animal cells do not have these materials. Cellulose enables plants to stand upright with out an internal or external skeleton. Plants also depend on insects for distribution of the male reproductive cells. We breathe oxygen from the plants, through the process of photosynthesis. Plants absorb energy from the sun, and carbon dioxide from the air and water from the soil. Animals take part in this cycle through respiration. Respiration is the process where oxygen is used by organisms to release energy.

Plants make the Earth’s atmosphere livable for humans and animals by changing carbon dioxide into oxygen. Plants are used by both humans and animals because we can use plants as food, plants as medicine, or plants as decoration. Leaves are the main food makers for plants. Because they capture energy from sunlight, and turn water and carbon dioxide into sugar and starch. One can undertake research science on plants, how plants grow, why they change colour, and one can also learn about different plants and ecosystems around the world, and how they are affected by human habitats. .

Plants play an important role with regard goods; they provide fibres and these in turns provide clothing. Wood is also used to build our houses, and burnt to keep us warm and cook our food. Plants importantimportant Plants important play important an important part in the quality of water because they hold the soil in place and control stream flow and filter sediments from water. Plants also prevent erosion.
They also play an important role by role byrole by providing the necessary habitat for wildlife and fish populations. The amount of sunlight and rainfall are limiting factors for both plants and animals because both affect plant growth.

References

Wikipedia contributors. Segmentation [internet].Wikipidia,the free encyclopedia;2006 march 24,11:10 UTC [cited 2006 May 08] available

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DESCRIBE THE VARIATION IN SHELL STRUCTURE THAT HAVE OCCURRED IN THE PHYLUM MOLLUSCA


Phylum mollusca are the largest one in all phyla, in both size of species and in number of species which have been described. The structure of the molluscar shell is complex. It consists of outer covering and inner layers. The outer covering consists of periostracum which composed of organic chemicals and inner layers consist of calcium carbonate. The periostracum is chemically distinct and is usually referred as conchin or conchion. These provide the protection to underlying calcareous shell layers against erosion. The periostracums also serve to form microscopic shell sculpted.


The calcareous shell structures are complex and variable. The calcium carbonate crystals are laid down in an organic matrix, deposited as calcite or aragonite. Calcite is more stable, it is the main shell substance in oysters. Aragonite is the major component of freshwater and land snails.


The phylum mollusca are characterised by flexible body plan. Mollusca consist of body mass, covered with protective shell which extends head and foot. Two anatomical structures are unique to phylum mollusca, i.e. Mantle and the Redula. Mantle is a flat from visceral hump. Redula resembles a toothed tongue. Molluscar body plan is bilaterally symmetrical, and unsegmented.

The body is divided into six classes which include: monoplacophora, Polyplacopora (Amphibians, Chi tons), Gastropods (snails), pelecypoda (Bilvalva, Claims. Cephalopods (squids and octopus), and Scaphopoda (tooth shells).The Pelecypods, Gastropods and Cephalopods are numerically dominant classes. Now we can focus on members of each of these classes to get their similarities and differences. We will also examine the Molluscan locomotion and feeding.
Gastropods

The Gastropods are more similar to the ancestral molluscan form than any other molluscan classes. They differ from primitive ancestor, in having enlarged head and visceral mass. Gastropods are marine, they are numerous forms in both fresh water and terrestrial environment. The foot is basically broad flat organ. Gastropods are the most successful group of Molluscs not only in terms of number of species but also in wide range of habitat in which they may be found. They have well developed head that includes tentacles, eyes and various chemoreceptor as well as mouth. Gastropods foot is flattened to a creeping sole. Locomotion in gastropods is composed of muscular contraction of foot aided by mucus secretion.
Pelecypoda

Clams, mussels and scallops are the members of a class Palecypoda. Bivalves don’t have much common with snails or the primitive molluscan form expect their protective shell. Bivalves are found in the every marine environment. Most Bivalves are suspension feeders, filtering small organism and organic particles from the water. Bivalves are generally sedentary. The foot, visceral mass, and the mantle cavity dominate the body and the head is suppressed.

Bivalves have developed from primitive molluscan form. The mantle cavity has been greatly enlarged, and the gills serve as a food sorting organ and respiration. The gills also serve as brood chamber for developing young. Bivalves do no appear much in common with snails. Bivalves are sedentary. The foot, visceral mass and mantle cavity dominate the body and the head is suppressed. Bivalves have lost Radula and the majority are ciliary’s feeders with plate like food.
Cephalopods

It includes the species which are largest known invertebrates, the most intelligent, and the fastest swimming aquatic invertebrates. They are forms with external shells and internal hard shell cephalopods are most invertebrates, and the relationship to mollusc is not obvious. The head and foot of cephalopods has become fused to form cephalised anterior end and there is reduction and loss of shell.
Aplacophora

It is found throughout the oceans and its habitat are exclusively marine saltwater. Aplacophora are small, cylindrical, warm like and less than 5cm long. It ranges from 1mm to3cm. Like other mollusc it has no outer shell. All aplacophora have simple mantle cavity
Monoplacophora

It is found in the very deep water. It is very thin and fragile. The shell is about 1,0to 3, 5 cmlong and the members of this class have a single, cap shaped shell similar to a limpet. The shell is small ranging in size from 3 to 30mm in diameter.
Polyplacophora

The shell is composed of eight overlapping plates and these are jointed to each other on the outer margin and underside to the girdles a thickened part of the mantle. The gridles consists of scales and spines. The plates used to allow flexibility.
Scaphopoda

The wider end of the shell was head and foot. Its shell is usually four layers which are used for identification. It has a short head, conical projection with a mouth. The shell surrounds as large mantle cavity. It has no ctenidia and gas exchange is through the mantle surface. The shell is open at both ends. The shell is curved, tubular and shaped like an elephant tusk. Its average is 3 to 6cm long but range from 4mm to 15cm.

REFERENCES


Mulcrone, S.R, 2005.Animal Diversity. Web. [Online] Available:
http://animaldiversity.ummz.umich.edu/site/accounts/information/Aplacophora.html
[2005 May 08, 10:17]

Wikipedia Contributors.Mollusca [Internet].Wikipedia, The free Encyclopedia; Available: http://en.wikipedia.org/wiki/Phylum [2006 May 05]

Linette Netshiheni
CSIR
Pretoria
0001
Cell: 0820446442
Tell: 012 841 2133
Fax: 012 842 3676
tnetshiheni@csir.co.z
Weblog: http://tnesthiheni.blogspot.com/

ADAPTATION REQUIRED TO MAKE TRANSITION FROM AQUATIC TO TERRESTRIAL LIFE

Amphibians are cold blooded vertebrate that spend some time on land but must breed and develop into water. Frogs, salamanders and toods are amphibians. The word amphibians is derived from the greek word amphibia, which means “two lives.” Ampbibians are dependence on both aquatic and terrestrial habitat for survival. Other may be fully terrestrial, even if they born on land. Others may only need a moist habitat while others may be completetly aquatic. Amphibians are vertebrates animals. Temparature body of the amphibians is depend on the temparature of the environment. They have no skins which means amphibians skins is naked, lacking hair, feathers, or true scale, and is highly glandular with mucous and glandular glands. Amphibians eggs, lay are shell-less and must be deposited in humid environment due to avoid desiccation. Most species are found in tropical and subtropical environmentin south america, asia, and africa.

Most amphibians are biphasic, meaning that they go through aquatic stage and a terrestrial stage. Respiration constrains on single eggs and egg masses have affected the mode of amphibians reproduction in water and in air, because aquatic eggs require less oxygen and it develop faster, and hatch ealier.The Indian tree frogs, use the secretions and wiping behaviour to lower evaporation and it also relied on moist microclimate for endure prolonged survival away from water. Frogs are examples of amphibians as they live both in land and in water. During Amplexus, large masses of eggs are laid in water and those eggs are hatch in the water. Tadpoles are survive by eating small aquatic insects until they finally metamorphose.

The reason why the amphibians lived from aquatic to terrestrial environment:
Western toads as an examples of amphibians, adults feed on variety of terrestrial insects and arthropods, snails and slugs. Toads breed in january to july and leaving back eggs in strigs of over 16,00 in very slow moving water.
Western spadefoot, they prefer to stay in open grassland or woodland and produce eggs in seasonal stream. They spend much of time in burrows but are active on the surface.
The foothill yellow-legged, they are found mainly in permanet streams and occasionally found in back water habitats, isolated pools and slow moving rivers. Adult eat bothaquatic and terrestrial invertebrates especially insects. The foothill yellow-legged frog needs, shallow, slow flowing water with pebble substrate for breathing sites. 300 to200 clusters eggs are attached under water to substrate. Tadpoles requires water for 3 to 4 months before metamorphosis. They are usually vulnarableto many problems experienced in terrestrial.
Salamanders are amphibians, related to the frogs and toads. California slender salamanders habits in a valley-foothill hardwood and mixed conifer. It forages under or within surface such as decaying logs, pieces of bark or leaf litter an earthwormsit is commonly laid underground. California newts, it also occur in valley foothill, hardwood, and mixed conifer habitstsduring spring (septamber to may) they move into creek to mate and lay eggs. During summer the aquatic larvae are common in Big Chico Creek where they eat many small aquatic organism.

The limitations to a terrestrial life of amphibians exhibit are: habitat loss, road construction, livestock activity: these livestock has resulted in the following disturbances: grazing and trampling have ruduced vegetation cover and create drier soil condition, water diversion, unnatural flow regimes, introduce non-native fishes and bullfrogs and activities which increase sediments such as road construction, logging and intensive cattle grazing within frog habitat
Clearcutting, disturbance related to roads trails and deseases are the most important limiting factors of terrestriallife. Deseases mass mortality of amphibians are caused by different deseases found on land. Climate condition have a major influence, such as drought which cause the death. amphibians
Terrestrial egg masses are more diffusion limited, because gravity and surface tension collapse them, preventing convection between the eggs, and restricting the source for oxygen diffusion. Terrestrial embryos are often larger than their aquatic counterparts and have higher demands for oxygen. Terrestrial conditions have selected for adaptations that reduce respiratory competition between embryos, for example, separating of embryos by large volumes of jelly or reducing the number of eggs in a clutch. The size of foam nests is unlimited, because oxygen for each embryo is supplied directly from the foam.

Reference
Jennings.1996.Amphibians of the Big Chico Creek.[Online]. Available: http://www.csuchico.edu/bei/BCCER/Biota/amphibians.htm%20[2006,May 11:20]
Linette Netshiheni
CSIR
Pretoria
0001
Cell: 0820446442
Tell: 012 841 2133
Fax: 012 842 3676
tnetshiheni@csir.co.za
Weblog: http://tnesthiheni.blogspot.com/

MORPHOLOGICAL DIFFERENCE BETWEEN CARTILAGINOUS AND BONY FISH


Cartilaginous fish includes species like shark, skates and rays. Sharks are the latest hunters’ of the oceans. Shark is big and fast. Because they have very strong teeth, it is easy for shark to break pray. Rays and Skates are more quiet or non-aggressive. Rays and Skates bodies are large. They have wings and tails. Wings help them to move smoothly through the water and they use tail as a wheel. Rays and Skates are bottom feeders. Cartilage is a type of dense connective tissues, and it is also have cells which composed of Chondrocytes, and the fibres which composed of Collagen and Elastic fibres, and Matrix which composed of Proteoglycans


Cartilage has strong jaws and their mouth is on the underside of the body. The eyes of cartilage are on top of the body. They can not see food as it enters their mouth. Some Shark solve this problem by touching their food with their nose first.
Some use powerful electro sensory system. Sharks, Skates and rays have rough skin. Sharks have 5 to 7 gills slits on each side of their head. Where as Bony fish have 1 gill on each side. Chimaeras or Gost sharks’ skins are smooth and have only one pairs of external gill openings. Cartilage fish give live birth and Bony fish produce eggs. Cartilage fish live in only salt water and bony fish live in all types of water.


Bony fish have hard cartilage for skeleton. The bony fish are classified into Lobe finned and the Ray –finned. Lobe-finned bone fish includes fish such as lungfish and coelacanth’s, where as Ray-fins includes the goldfish, tuna, and trout.
Bony fish are true fish, such as snapper, groper and gurnard. They have a bony skeleton and single pairs of external gill openings. The mouth is generally at the front of the body and they have a tail fin, with the top and bottom portions nearly the same size. It has relatively short tube. Bony fish reproduce by external fertilisation of eggs and releases them into water. The male releases sperm called Milt into water. Then Milt fertilise eggs
Bony fish is a fish with a skeletal system that is made out of cartilage. Their liver is filled with oils which keep them from sinking. They have internal fertilisation.


The bones of fish are made mostly by calcium but Shark does not have any bones. Shark skeleton is made of cartilage, and have no bladder, but bony fish have a gas filled swim bladder which enables them to float in the water. Bony fish have movable parts were as shark does not have. Shark can turn around in a smaller space than bony fish.

On top of shark it is dark in colour which is called dorsal side, and light colour on the bottom which is called ventral. Shark have noses that use for smelling, not for breathing one can find their pairs of nostrils on underside of their snouts. The eyeball of shaka is cornea, iris, pupils, lens and retina. Shark teeth are parallel.


Reference


Studios, A.R. 1997-2006 Biology for kids’ vertebrates’ fish [Online].Available from:
http://www.biology4kids.com/files/vert_fish.html[2006, May 09 13:00]

THE SIGNAL USED BY INSECT TO ATTRACT FOR SEXUAL REPRODUCTION

Insects are invertebrates. Insects are more successful because they have protective shell; they are small and most of them can fly. This shows us that it easy for insect to escape very quickly from enemies and easy to travel to new environments. They need small food and live in small cracks and species. Insects are directly useful to humans by producing honey, wax and other products. They also play an important role as a pollinator of crops, natural enemies of pest, scavengers and food for other creatures.
Sexual reproduction

They are male and females insects that mate and reproduce sexually. Sometimes there is shortage of males then some female’s species may reproduce. In a few species females produce only females. Most female’s insects have one or more spermatozoa where sperm can be stored and can be support by secretions from the spermsthecal glands. Female’s reproductive organ consists of ovaries, bilateral Oviducts, a common Oviduct and a vaginal.
The male reproductive systems consists of paired testes, where the sperm produced, seminal vesicles and is where sperm are stored,, accessory glands and a common ejaculatory duct. Mating is important for sexual reproduction. After mating, female’s insects from many species become less attractive.
Mating strategies
Insects used displays or dancing to attract females to mate. Male fight or decide the winner by comparing size. Some female insects not mate unless the male is in possession of a suitable territory or food source. Female moths have smell glands on the abdomen that secrete. These chemicals attract males. Some male hide a pheromone to make the female to mate. Some insects used sound to mate but others used visions to mate. Females’ scorpion flies require a marriage gift of food from the male before mating. Then the males’ mates with her while she eats, because of these male are selected by the size and quality of gift.
Mating strategies through vision
Butterflies are one of the important types of insects. Butterflies used colour and movement to attract male to mate. Males will follow coloured imitation of females. Some male’s flies form dense group. Then females are attracted by sight of these groups and they start to enter and select mate. Male fireflies are attracted by, and fly to, the light beat produce by the wingless females. Both sexes of butterflies are meet on hill tops or other geographical outcropping where they will select a mate, but other insects form a group.
Mating strategies through sound
Mosquitoes are one of the important types of insects, and the male mosquitoes are attracted by the message produced by the wing vibration of the female. But some grasshoppers and cicadas are attracted by the sound produced by their males. Crickets use their burrows to resonate the sound, but cicadas use the enlarge empty space in their abdomens. Some leafhoppers communicate by using substrate vibration.

Males are allow to leave females after mating, giving those males opportunity to increase their reproductive success by locating and inseminating additional females. In many insects’ species, seminal fluid received from fluids during mating mediate post mating behavioural and physiological changes in females.

References

Hoffmann, M.P. and Frodsham, A.C. 1993 Insect Facts and Information. [Online]. Available from: http://www.ivyhall.district96.k12.il.us/4th/KKhp/1insects/buginfo.html[2006, May 08 13:11]
University of Sydney February, 2004.How the sexes find each other. [Online] Available from:
http://www.bugs.bio,usyd.edu.au/Entomology/Internal Anatomy/reproduction.html.[2006 May 10:00]