Thursday, February 15, 2007

The Invasion of South Africa Biome by Feral Species (Opuntia Stricta - Prickle Pears)

The Opuntia Stricta has invaded South Africa biomes. It was regarded as the feral species, this because it invade the rocky slopes and river banks from domesticated environment. Opuntia Stricta is an indigenous species of North America1. It has been introduced in South Africa and other continent as ornamental plant, garden plant and it was used as a fence. The species grow as shrub.1

The Opuntia Stricta has a fleshy stem with no leaves 3.The fleshy stem grows like leaves and it has spines with hairy features. The spines make it unpalatable to other animal species. The Opuntia Stricta bears fruits that are palatable to humans. It was studied that it can cure sugar diabetes and stomach-ache. It also helps to reduce alcohol hangover. 3

Opuntia Stricta favourable habitant is in the rocky slopes and in river banks. However, it also invades disturbed area such as cultivated area and wetlands. The Opuntia Stricta has invaded the rocky slopes and riverbanks out compete the indigenous species.1

In south Africa Opuntia Stricta has been declared weeds this because when it invade the area it grows in dense that end up restricting the growth of other plant species. In Kruger National park (South Africa), the Opuntia Stricta has invaded large area. When opuntia stricta invade the area, it replaces other species.1

The opuntia stricta spread through garden wastes, some with water current.1 The Opuntia Stricta have the ability to grow from any parts of its fleshy stem. Birds and animal can spread other species of opuntia stricta like common pear 2. The management of this opuntia stricta considered difficulty when is done physically. This because it can grow again if it is not disposed well 2. Spraying with woody weeds and biological control are effective if they are applied well. This is because in warm climates it needs to be reapplied again in winter.2

In general, the feral species can have more impact in our ecosystem. This need to be addressed and managed before the species invades our biome from domesticated species.


1. Global invasive species Database, 2006. [Internet] Cited 2006 Jan 24 Available from:

2. Opuntia stricta [Internet] Cited 2006 Jan 24 Available from: Wikipedia contributors. Opuntia [Internet]. Wikipedia, The Free Encyclopedia; 2007 Jan 22, 19:39 UTC [cited 2007 Jan 24]. Available from:

Tuesday, May 16, 2006


Evolution of bird from small Theropod Dinosaurs as it was suggested by paleothropologist can be the start of flight evolution. It was suggested that this flight evolution has evolve from ground living species, so with the evolution of feathers bird tend to have a chance to live on skies. Some paleothropologist suggest that flight evolve as result of benefits that are found in the sky. For example, small insect that are found on air, flying birds species feed on them.

Flight is the mode of locomotion used by most of the world birds species. It is important for birds; for feeding, breeding and avoiding predators. They adapt to fly because they have modified limbs as wings. And because flying need energy bird had evolved several other adaptations to improve flying. They have skeletal hollow that serve to reduce weight and it also lost some bones. The earliest birds where having bones that, the modern flying birds do not have. Bones such as bony tails, toothed jaw which has been replaced by lightweight beak

Bones which are lost are those ones that are necessary or that does not pose any impact on the surviving of birds. Birds have developed the body which weigh less than their ancestor, which enable them to fly. It have vanes on the feathers known as barbules that close them together, allowing feathers to stretch and giving bird strength to fly.

Anatomically bird had undergone modification, early birds where having large muscles on hind limbs. Because of modification, it was reduced as the pelvic gridle which provides support for the bird to weigh less and enable them to fly. This anatomical change in most of the birds helps them to evolve for flight, this because they weigh less than their ancestor theropod dinosaurs which was ground living species.

The limbs that develop from bird as the wing helps the bird to fly; they play an important role for flight as they are the ones that hit the wind. This forelimb is composed of three limbs that function to balance the bird on the air. Feathers also enable the bird to hang up on the air.

Adaptations of bird for flight can be suggested as the way in which bird have to survive. They evolve a wing, which was used as limbs to catch preys; they then become modified and become wings to fly. They fly to avoid predators, and also the way to access pray, insect on the air. Most of the diets chosen by birds are on air because insect can fly or tall trees have flowers that bird feed on. Which is difficult for ground animal to feed on that diet? so it encourage the bird to develops wing for flying .

Scientist also suggested that for bird to be able for flight they need to be endothermic, so that they could be able to maintain energy level that they use for flapping wings. but it was indicated that the warm-blooded animals are mammals, so bird are not mammals but because they originate from dinosaurs which is regarded as warm-blooded animal and also they have feathers that hold temperature. They are able to maintain their temperature

In general most of the species adapt different behaviour because of the environment they are living in. predators influence some species to adapt different behaviour, and also diet that different species choose to feed on can also introduce different behaviour on certain species. Birds avoid under ground predators by developing mode of locomotion which enable them to fly higher so that the predators cannot access them. They also choose diet which is abundant in the higher level which is only accessible by species that can fly only, diet such as nectars and flying insects.


1. Hasting L.Your guide to animal/wild life, Birds. [Internet] cited 2006-May-09 Available from:

2. Adaptations for Flight.[Internet]cited 2006-May-09, Available from:

3. Bird flight.2006-May-10[Internet]cited 2006-May-09.Available from:


Monkeys comprise 90 percent of the 145 living species of the suborder anthropoidea. They are the most successful primates populating the earth. They have different class of anthropidea which have many supper families such as Cercopithecidea which is regarded as the old world monkeys, this old world monkeys are mostly found in the continent of Africa and Asia. While Cebidae is regarded as new world monkeys this new family have four primate families Aotidae, Pitheciidae, Atelidae and Cebidae.

Old world monkeys are known as catarrhine and the new world monkeys are known as platyrrihini.this two groups of species can be differentiated from each other by their physical appearance.Platyrrhine nose is flat as compared to the one of the catarrhine, their nostrils are separated by a wide septum, while of the catarrhine are separated by a small septum. Platyrrhine have three molars which are large as compared to the one of the catarrhine which are two and sharply connected cusps.

They are also differentiated by their characteristics, they have different behaviour. Males of the platyrrihini are involved in the infant caring, most of the time the males will carry the infant on it back and give them to their females for nursing. While the old world monkeys male do not care for their infant.

The platyrrihini mainly live in trees and they are herbivores, they only eat leaves, fruits, nuts, gums and occasional small preys such as insects. While catarrhine live in broad habitats, they spend most or some of their day on the ground. These monkeys have hairless callous pads, on their rumps which may be adaptations for long sitting or sleeping on rough branches and stone and the new world monkeys do not have that marks.

The new world monkeys are having long tails, often known as prehensile tails, and they are arboreal and nocturnal, while of the old monkeys are easily observed, they never had a prehensile tails. The new world monkeys sometimes use their tails as their third hand. Another difference between the two monkeys is their body; the old world monkeys are having large body size as compared to the new world monkeys. And the old world monkeys are having bright colourful colours especially in their face; on the other side the new world monkeys are having dark colours and small body with lots of fur that made them to look big.

In conclusion, it is easier to differentiate the old world from the new world monkeys simply by their appearance, when you are distanced from them you can check their colours, body weight and when you are not far you can also check their facial appearance as they are different. Also their characteristics are different new world monkeys prefer to live on trees while the old monkeys occupy different habitant and they prefer to live on ground than on trees.

All these monkeys irrespective of their differences they share one common character, both of them are intelligent and they behave like humans.


1. Anthropology 1, new world (America) and old world (Africa and Asia) monkey: A comparison, [internet] [cited 2006 May 11] Available form:

2. Wikipedia contributors. Monkeys. [Internet]. Wikipedia, The Free Encyclopedia [cited 2006 May 12] Available from:

3. Wikipedia contributors. Monkeys [Internet]. Wikipedia, The Free Encyclopedia; [cited 2006 May 12]. Available from:

Monday, May 15, 2006


Placental mammals are considered the largest group of mammal species. They are class of vertebrates animals, which is characterised by mammary glands. In females it produces milk to nourish their offspring .the placental animals are warm-blooded animal that can regulate their body temperature. This type of species also has hair and fur that they use to protect their skin against cold as their skin insulate. This placental mammal includes species such as elephant, whales, bats and farm as well as work animals. Also human are regarded as placental mammal.

Placental animal have colonise all the environment land, water, and air. Because they differ in the way of surviving as they do not share same diet and the environment. Some placental mammals are carnivore, herbivores while other is omnivores. They differ on diet and the environment they live in, some live in the aquatic environment, and while other live in terrestrial environment.

Placental mammals colonize different environment, because they can regulate their body temperature which enable them to adapt in any environment. Increase in metabolic process which is influenced by the food they eat helps them to have better adaptation in different environment. Some placental mammals live in the aquatic where there is a deep shallow sea which is colder than the terrestrial but because they can regulate their body temperature, they are surviving. While other are surviving in the Iceland where it is cold

Some of the placental mammals can survive in both environment, this happens when other go to aquatic environment for reproduction, while other from aquatic to terrestrial environment to lay eggs, so this shows that they can adapt various climate change that happens as in the water is cold and in terrestrial there is fluctuation of temperature. because they can moderate their temperature they find it simply to adapt.

Different mode of locomotion also encourage the placental mammals to colonise many environment, some mammals are quadrapedal ,animal that use four limbs to walk .while other are bipedal they use two limbs movement. Most of the species that uses limbs for movement survive on land than in water this because they choose diet which is abundant on land. Whereas species that are found in aquatic environment they use fins to float.

Placental mammals colonize the most habitant because the can move and they can regulate their body temperature. Also the diet they feed on is found in all environments. Because most of the endothermic process that mammal species have it helps them to adapt in any environmental condition. This occurs because they can regulate their body temperature, when the environment is not conducive to them.

In nutshell placental mammals are warm-blooded animals that can regulate their body temperature and they have different mode of movement helps them to colonise any habitants as they can adapt. The diets they have chosen also enable them to colonize most of the environment.


1. Hastings.L. Mammal Adaptation.[Internet] [cited 2006-May-11]Available from:

2. Mammal, [internet] [cited 2006 may 8]. Available from:

Friday, May 12, 2006


The placenta is a temporary organ which is present in females especially during pregnancy (2). This name is given to the mammal that have placenta, that connects the growing embryo within uterus to the mother. Placenta is composed of two parts the genetically and biologically part of the fetus and the other part of the mother. The fetus is implanted in the wall of the uterus where it receives nutrients and oxygen from the blood of the mother and passes out waste. (2)

While Marsupials can regard as non-placental mammal, they reproduce by lying eggs. In some marsupials there is rudimentary placenta that functions on for short period. Its reproduction is different to that of placental mammals; it develops a yolk sack in the womb which delivers nutrients to the embryo. The embryo of marsupials born at an early stage of development, it crawls up to the belly of its mother and attaches itself to a nipple. It stays at the nipple for a period. Then the offspring passes a stage where it can leave its mothers pouch temporarily and returns for warmth and nourishment (1).

Birth in marsupials occurs very fast depending on the egg yolk type, and also the type of reproduction speed up the birth process. It only takes twelve days for marsupial embryo in the reproductive track, whereas in placental mammals’ gestation period takes long, because the offspring will need to be fully developed before birth. It takes nine months for placental mammal to give birth.

During reproduction placental mammals develops a placenta that protect the fetus from the mothers’ immune system, while in marsupials they develop a complex fetus. In placental mammals, if they give birth before times the baby or fetus become prematurely and it will need care the same way the marsupial do to their embryo, carrying it to the belly for a period.

When the placental mammals are pregnant the process of oestrus cycle are likely to happen until the end of pregnancy. Whereas in marsupials the oestrus cycle does not stop it takes place. In marsupial the ovarian inhibition is mediated by lactation or suckling stimulus. These regulatory modifications are important because the baby will no longer be carried internally so negative feedback stimulus from the presence of the babies must come from nursing activity.

Differences in these two modes of reproductions are the time that the offspring take in the uterus. Also the development of the embryo is different to each other. As in marsupial the embryo is separated from the body of its mother. While in the placental is connected to the mother. Mating system in marsupial is different through out the year. Some species are single and they only come together to mate and this pattern of social behaviour reflect promiscuous mating systems.

In conclusion mode of reproduction differs with type of species and also the size of the species involve to the way in which species reproduce. Species that reproduce by placental must have big body as they have to carry the embryo for couple of months, while those with small bodies do not carry embryo in their belly they reproduce by marsupials process.


1. Ashcraft.C.W. Marsupial Evolution And Post Flood Migration.[Internet]cited 2006-May-10] Available from:

2. Opossum Reproduction And Life Cycle [Internet][cited 2006-May-10]Available from:

3. Wikipedia contributors. Marsupials [Internet]. Wikipedia, the Free Encyclopedia; 2006 May 9, 17:16. PTA [cited 2006 May 10]. Available from:

4. Wikipedia contributors. Placenta [Internet]. Wikipedia, the Free Encyclopedia; 2006 May 7, 18:21. PTA [cited 2006 May 10]. Available from:

5. Wikipedia contributors. Umbilical cord [Internet]. Wikipedia, the Free Encyclopedia; 2006 May 8, 18:02. PTA [cited 2006 May 10]. Available from:


Dinosaurs fossils were found about 230 million years ago. It was suggested that they were vertebrate animals. They dominate the terrestrial environment for 160 years before extinction. This left many Paleothropologist with suggestion that relate modern bird to be the direct descendent of Dinosaurs. (2)

Most of the species found on land was suggested to be warm-blooded this include birds and mammals.paleothropologist also suggest that because of the body and characteristics that the dinosaurs have, can regarded it as warm-blooded animals. This because most mammal or birds with large body, they have high metabolic rate that can regulate their body temperature.

In warm-blooded animal it was suggested that their body can retain heat for long period and also the chest cavity can hold huge hearts that increase metabolism. The bone structure that the dinosaurs have also suggested that it play a part on heat retation, the parallel rows of plates on dinosaurs has been interpreted as additional temperature –control mechanism. This plate is made of bone-like sponge consists of many blood vessels that can absorb heat from the environment or disperse excess heat. (1)

The characteristics that dinosaurs have for living also indicate warm blooded animal, its character of migrating, instead of hibernation during cold periods shows that they can adapt any environmental change they encounter. Which is impossible for cold blooded animals? (2)

The anatomical analyses of dinosaurs suggest that they were active animal, moving fast which increase endothermic metabolism rate. Also the diet they have also increase the metabolic rate, this because the herbivorous dinosaurs require hundreds kilos of vegetation a day to sustain their enormous bulk and that they had a unique endothermic metabolism fuelled by the heat given off by non-stop digestion. The metabolism rate was the insulator of heat in dinosaurs because they do not have feathers and hairy skin; its skin is consisting of hides with scaly and bony bumps that do not insulate. (3)

Some paleothropologist suggest that dinosaurs maybe in between the warm blooded or cold blooded animal. But with the DNA test of the bones it shows that dinosaurs are warm blooded. “This because warm blooded animal grow fast than cold blooded ,this was proven by scientist Jack Horner through the bones of a tiny baby dinosaurs found in hadrosaur nests. But as scientist has conflicts other suggest that the heart of herbivores dinosaurs consist of four chambers instead of three which is common to warm blooded animal.”(2)

Evidence studied can reveal that dinosaurs were warm blooded animal, this because they can maintain their body temperature by increasing the metabolic process through eating lots of vegetation that will need non stop digestion. And also by moving fast which increase the endothermic metabolism. It was suggested that dinosaurs have large body that can regulate temperature, because they have high metabolic rate.

In general warm blooded animal maintain their body temperature at their constant level, this regulation of metabolic rate helps them to adapt any environment as they can increase or reduce their depending the surrounding environment.


1. Were Dinosaurs Warm-Blooded .1999. [Internet] [Cited 2006-May-09] Available from:

2. Wikipedia contributors. Dinosaurs [internet] Wikipedia, The Free Encyclopedia [cited 2006-May-09] Available from:

3. Dinosaurs [internet] [cited 2006-May-09] Available from:,

Thursday, May 11, 2006


Herbovores are refered to animal that adapted to feed on grass and plant material,the diet in which most of herbivores feed are diferent depending on the environment they live in.Diferent type of herbivores have selcted thier diet to feed on,this because of the accessibilty they have to that foliage.small animal cannot chose the diet of big trees that found in the forest where there is predators so they have to chose area where they can access.

Most of the herbivores are vulnerable to canivores so they chose diet which is not close to the predatores.they prefer to live in grassland where they can live in social groups than in the forest.So they choose feed in the area where there is less adaptation of canivores predator.Most of the diet that many herbivores have, are composed by grass and leaves.

This choosen diet also pose problem during digestion, this because most of the herbivores feed on cellulose which have many energy scource. In most of herbivores, they digest food through enzyme digestion ,and it is dificult for enzym to break down cellulose because it is composed by organic substances .this cellulose can only be broken down by mechanical means ; extended chewing or fermetation

These problem of digestion in herbivores,tend to influence them to maintain bacteria in their stomach for the process of fermetation which simplify digestion.,but even though they use this process it fail to digest vegetarian meals,which take long to be digested .but some solve the problem by having long digestive system.

Animal with long digestive sytem reduce the problem they encounter,for digestion.They reduce the problem by having ruminat stomach, which help to extend chewing as this ruminat keep food for a time being, when feeding and during leisure they return to the mouth for easy for digestion within ruminats this because food undergo extensive fermentation. In the rumeinats theres is lots of bacteria and protozoa,this are micro-organisms which is responsible for breaking down of cellulose.and this cellulose is the main cause of digestion problem in most herbivores.

Some herbivores solve the problem of digestion by growing big,or by becoming giant. This help them, because they will have long digestion which include ruminats.and this long digestion system allows them to digest toughe plants.In most giant herbivores it take a day for them to digest food,so this influence giantism.

Because of cellulose they eat, metabolisim rate increase and it was sugested that animal with high metabolic process can grow rapidly.It mainly happen in animal that live on land.In terristrial environment competion of food resource are great,so for giant herbivores it become simple for them to access higher foliage and also have strength to reach their food. For example, elephent and giraffe,they reach 18 feet high and they can access high foliage,while elephent also reach 18 feet high with weight around 8 to 10 tonnes ,this enable them to use great bulk of tall trees.

This enable many large herbivores to feed on high foliage,while small herbivores feed on grass or small foliage.being large fo this herbivores helps then to maintain body temperature,and also to be less vulnerable to predators. This because having large body also increase the strength that can prevent small predators to attack them.

In nutshell, diet that herbivores choose to feed on have impact on digestion and this influence the change in body structure that most herbivores have.They change their body structure to solve the digestion problem they encounter.and also to have better access to food rescource as there is competition ,large animal can access to high foliage.But all changes that herbivores have of becoming large is because of the problem they met, failing to digest cellulose pose an impact,that’s why we find large animals on land .

Reference :

Chang.A. Is there any evolutionary advantage to gigantism? Did sauropods continue to grow throughout their lives, like some reptiles and fish do?[internet] 2000-October-16[cited 2006-May-10]

2. Findlay A.L.R.: The Gastrointestinal System: an introduction Carnivores, Omnivores and Herbivores[Internet]1998-February[cited 2006-May11]:

3. Kaplan.M.1995. A very brief overview of digestion in green iguanas and other herbivorous lizard species.[internet].2003-August-11[cited 2006-May-11].Available from:

Wednesday, May 10, 2006

Amphibians are grouped in phylum chordate, subphylum of vertebrate and class amphibian. These Vertebrates comprise of many living chordates, and they have evolved an enormous variety of forms. This is divided into eight classes; four are aquatic which is grouped into super class Pisces, while four are terrestrial. They are grouped as super class Tetrapods or four-footed animals.

They have different movement aquatic species like fish moves by weaving of the trunk and tails, most of them have sets of paired fins pelvic and pectoral they do not have limbs. The terrestrial species move in the form of wriggling which is similar to those of fish even though it has limbs that support the movement.

Some have limbs that make movement simple, like Frogs and toads use their muscular hind legs for jumping. While other amphibians have lost their limbs and most of that species are burrowing forms.

As evolution are taking place basic forms of structure evolve to perform number of task, example tetrapods, forelimbs becomes used for grasping climbing, flying, burrowing and swimming as well as terrestrial locomotion. In amphibians, limbs improved for locomotion. These evolve into upright position which is different to what amphibian have of sprawling, and have some tendency towards bipedalism among reptiles and birds.

All these changes in limbs evolve from fish and the vertebrates that start to evolve on land it was suggested by scientist that many of limb and muscles developments needed for walking on land before fish and limbed animals split.

When Tetrapods moved onto land they lose connection between the skull and the pectoral girdle as they move on land. The pelvic girdle became closely involved with vertebral column using the sacral vertebrae. While in fish the pelvic is made up of one
And basiterygium (paired bone). In amphibians, the basiterygium divided into the ilium and ischium. Because the pectoral girdles are not attached to the head of terrestrial animal no force of walking can be send directly into skull which shocks the brain. Amphibians did not obtain the strong girdles like fish, because they evolved from fish.

Loss of limbs is very common in all lineages of vertebrates, this because fishes and amphibians, has evolved many times and they all move by the use of the limbs. While if mammals or archosaurs were to lose their limbs, their axial muscular would still be weak and unable to support the animal.

Only one group of mammal (whales) have ever lost either of the limbs. Whales develop a larger, broad tail which is considerably strengthened their axial muscular. Whales and snakes are animals which have lost limbs and are still retain some element of the girdles

In conclusion changes in adaptation tend to evolve in the change of structural patterns of the species, this result because some of the species live in both environment and they would like to have features that will allow them to move. so evolving of limbs in amphibians and vanishing of limbs are also influenced by the environment that they choose to live in,


1 Limb evolution [internet] [cited 2006-May-09] Available from:

2. Amphibians [internet] [cited 2006-may-09] Available from:

Mr Elelwani Muanalo
NISL- Ecological Informatics Student
CSIR Pretoria
Tel: +27 12 841 2133
Fax: +27 12 842 7024.
My bloger URL:

Fish have various groups, which is made up of three living classes that hold an important place in evolution history and modern ecology. Fish are the first known vertebrate (animals with backbones) and also the first species that evolve in land –walking vertebrates, they are the first known true chordate that has been found. (1)

It was suggested that fish evolve before the Devonian periods which was referred as the Age of fishes, fishes where aquatic species. Then at the end of Devonian periods tetrapods (vertebrate) which evolved legs which they can be used to walk on land evolve, and this evolution led to the adaptation to land in the form of amphibians.(1)

Ostracoderms was the first fish to evolve in the period of Cambrian about 510 million years ago and became extinct at the end of the Devonian periods it was jawless fishes found in the aquatic environment, it was covered by scales this Ostracoderms were less than 30cm long and it was placed in the class of Agnathans. These jawless fishes were the first vertebrates. Jawless fish was having circular mouth with a sharp spine tongue which is used for sucking and filtering food. Most of the species under this class agnath was not having fins except for a fringe around the tail, And they possesses the beginning of the backbone in a form of cartilaginous. (3)

In agnath group they were other small fish like animal which possessed heavy protective covering –plating, this was originated from the deposit of salts from food they eat. This plating was suggested that it tend to harden the gill arches to become the upper jaw and the bottom gill into lower jaws. And this evolution of jaws on fishes was important because it permit the fish to feed on variety of foods. Having jaws allowed them to be vigorous hunters as opposed to passive filter feeder. Being vigorous hunters led the fish to have large diversity of adaptations.(3)

This salt deposit marks the first presents of bone in the fishes which influence the evolution of vertebrates. The bony plate provides protection against sea scorpions that co-existed at the same time.(1)

Some of the bony scales in the skin around the mouth enlarge and became first teeth, while the lateral flaps of skin evolved into true fins which improve the swimming. Because of the food they eat with salts, lots of features evolved other develop some back bones. Species such as Acanthodii develop internal bony skeleton running longitudinal through the body. And this type of species was likely the ancestor of the bony fish we know today. (3)

Bony fish are often regarded as "true" fish. This group includes most of the fish we are familiar with to day. They are characterised by short jaw with lower jaw articulates with vertical quadrate it also have symmetrical caudal fin for swimming. They also have bony skeleton and single pair gill opening this are the advance bony fish we have today in the class of vertebrate. (2)

In general there is much to be learned from fish, they have evolved to fill every aquatic and inland environment with variety of adaptation. Fishes are important in evolutionary steps they are the first known vertebrate and also influence the evolution of all living vertebrate on land.


1. Kagle R.1997.The Evolutionary Steps Of Fish [internet] [cited 2006- May -08] Availablefrom:

2. Fish Distribution [Internet] [cited 2006-May-08] Available from:

3. The Major Radiation of Fishes;[Internet][ cited 2006-May-08] Available from:

4. Wikipedia contributors. Osteichthyes. [Internet] Wikipedia, the Free Encyclopedia; 2006 May 07. [Cited 2006-May-08]Available from:

Mr Elelwani Muanalo
NISL- Ecological Informatics Student
CSIR Pretoria
Tel: +27 12 841 2133
Fax: +27 12 842 7024.
My bloger URL:

Tuesday, May 09, 2006

During the period of Cenozoic era, co-evolution between plants and animals species occur. It has been profound that certain plants and insects influence another in evolution, in a process known as mutualism where all organisms benefit from each other. They firstly evolve in the aquatic environment before they evolve on land.

Species that co evolve were single cell plant and multicelled eukaryote organism, the blue-green algae was the single cell plant which evolve on the sea. It was the first species to generate its own food in a process known as photosynthesis where sunlight and water are used; during this process oxygen is also generated. While animal cannot produce its own food, they depend direct or indirectly on plants for its survival, and for animal to be evolved on earth it is traced back to plant this show dependency of animal to plant.

The oxygen that the algae produce spread all over the aquatic environment, it began to fill the atmosphere and this made it possible for other organism to develop. Because of high concentration of oxygen produced by algae in the atmosphere, it tends to give access to animal species to evolve on land. Oxygen form part of ozone layer in the upper atmosphere which tends to block the dangerous ultraviolet rays of the sun, these rays was making it impossible for organism to live out of water. But it was simple for plant to survive on land because they can utilise the ultra violet rays into food.

Simplicity of plant to convert sunlight into food made it possible for plant to evolve on land, and the first plant to evolve on land was Mosses. This made it possible for other animal to evolve on land, because of the oxygen generated by plant which forms the ozone layer that block the ultraviolet which restrict life of organisms to exist on land.

Mutualisation which develop between plant species and animal species during co evolution influenced by the resource that one need to survive, plant release oxygen as by products which is used by animal for its survival while animal release carbon dioxide as by products which plant species use it during the process of photosynthesis. For each species to survive it have to depend on the other directly or indirectly.

This dependency between plant and animal species can be seen during reproduction, where plant depends on organism to transfer pollen grains to the female flowers. This helps the plant to reproduce and increase plant population, which is simple method to transfer pollen than wind pollination which need quality seed to be dispersed. While organisms benefit from plant through food and habitant for reproduction that the plant provides, mostly this happens to insects such as moth and bees.

Sometimes plant and organisms become total depend on each other, this happen when one insect only function to pollinate their pollen grains only and it find habitant on the same type of plant ‘s flower. Some become specific to that species only and they protect that species form herbivores. For example, species such as Yucca (Plant) and Moth(organism)they depend on each other yucca provide habitant for moth and allows it to reproduce on its flower where its larvae (caterpillar) live in developing ovary and eat yucca seeds, while moth function as the pollinator.

This mutualism can also be seen in the acacia trees and acacia ants, these ants are specifically depends on the acacia tree for foods. They tend to protect the acacia tree from the herbivores which feed on it and also prune the seeds of any plants that found under acacia tree. This ants sting the animal that feed on acacia or scratch on it, and the ants benefit from the substance that the acacia produce as a food.

In conclusion, plants and organisms depend on each other in a process known as mutualism where all benefit. plant play a role in bring life on earth as the primary producer of factors that sustain life, while animals generate carbon dioxide that sustain plants and also increase the population of plants in the process of reproduction, organisms function as the pollinator.
All in all most of the species in the environment depend directly or indirectly to the other.


1. Kazlev.A.M. 2002, Plants, (Land plants) [Internet] 2003 April 28 [cited 2006 May 08].Available from:

2. Kohler, S. Plants, [Internet] 2006 May 8, 14:30. UTC [cited 2006 May 07]. Available from:

Largely species of insect organisms have males and females species that mate and reproduce sexually. They can reproduce by lying eggs, while in some insects egg produced inside the female and are born after a short time. And for those species to do reproduction they have to underwent mating period which is different depending on the type of insect’s species. 2

In some insects they have Courtship ritual. Which they perform before they can have mate, while on the other insect there is no sign prior mating, female are often stroked by males, using legs or antennae dance patterns may be performed.2

There is different method that the insect use to attract mating; it can be regarded as mating calls or courtship. Some insects release gland known as pheromones mostly it happens on intraspecific interaction, while intraspecific interaction species release allelochemicals.all this chemical are known as semiochemicals it is used for attraction, repellents and stimulants of male insects species for mating.1

These pheromones are unique for each species to know that there is an insect of the same species which is ready for mating, and it is simple for male species to follow the scent trail. Insect can detect the smell from distance. It was suggested that moth insect can detect the scent close to eleven kilometres. 1

In some species during the arrival at the female territory male secrete the scent for courtship, and it helps females to access the quality and quantity of the male. And most of the scent or pheromones that the male release are the scent from the flowers.

Insect like butterflies use colours and movement for attraction, male butterflies will be attracted by the coloured imitation of females, while other flies also forms a compact swarms that attract the females.1

Other species uses sound for attraction, frogs croak and chucks to attract male frogs for mating and bird sing a song for mating calls. Some insect that use sound for attracting males for mating , are Female grasshoppers, crickets and cicadas males.

Envious, happens in every species, most of the organisms that use signals for mating they have different method to protect their sperms from other male some stay with their mated females to guard them preventing her for mating again. They also extend copulation which prevents other males to mate with her in that period. There is completion for mating in species so they have to prevent other to mate with the species that they mate. some species produce chemicals that plugs the vagina of the female after mating and this give her opportunity for her to mate once while other have genital apparatus that push the arriving sperms back out of the way in the female spermathecae. Because most of the species like to have their own product some have the apparatus that they use to remove the sperms of previous males from females. 1

In general most of the species that cannot undergo courtship they use pheromones and allelochemicals to attract males for mating while other uses sound to indicate that they are ready for mating. So this method of mating call or signals that they use helps the male insect to identify the insect which is ready for mating, different species know signs and smell the scent for attraction of the species of the same group.


1. Entomology [Internet] updated 2004 [cited 2006- 05- 08] Available from:

2. Encyclopedia Smithsonian; Mating Insects, [internet] [cited 2006-05-08] Available from:

Monday, May 08, 2006

First molluscs made appearance in our world 600 million years ago and during Ordovician period, six of the seven classes of molluscs represented today was present. Many of these first molluscs were simple, worm like animals having segments. These first molluscs crawled primitive seas and eating small bits of foods. Because they have soft bodies they were vulnerable in the ocean filled with predators as they are easily eaten, early molluscs developed hard shells to protect themselves from predators they manage to survive because of having shell.

Changes in the environment led to change in shell structure; some grow large while other looses their shell completely, because of adaptation and protection that they want for survival.

They tend to evolve in freshwater and land rapidly today molluscs live in almost all parts of the world from the deepest ocean to high mountains. They have found their niche where they can survive, but for them to survive they have to have moisture because of their soft bodies which need moisture at all times. Those which live in desert environment they retain moisture by curling up in their shell, secreting mucous and stay hold up until next bit of moisture comes along.

Because mollusc they have soft bodies they usual produce an external skeleton, known as exoskeleton. It is formed by calcium carbonate (CaCO3) it is a hard part that cover on the back of molluscs its purpose is to protect and support molluscs. And all molluscs they have common feature which is present, the flesh mantle. Which secretes, modifies and lines the shell with mucous.

Different molluscs have different shell structure depending in the environment they are living in terms of predators, species that are found in the oceans have a dome shape shell that have eight piece plate which overlap other plate behind in a very tight way for protection .this protect it from violet serge of ocean waves this type of shell is found in the primitive molluscs polyplacophora.

Other is bilateral shell with a disk shape valve less than 25mm, this type of shell is thin and fragile. The first part develop a coiled chamber covered with horny periostracum or sheath which have scars inside and it form segmentation this type of shell was found in the class of monoplcophora.

Scaphoda have simplest shell structure than all molluscs it have a shell that resemble a tusk of an elephant, it shell is elongated cyndrical tube open at both end the shell usually heavily ribbed and has small slits at the narrow end with different colours ,it have a she

While other class of molluscs such as Aplocophora do not have shells and there is no fossils that indicate that they were having one. The flesh mantle that they have does not produce shell but it produces calcareous spicules which protect them from predators as it become less palatable.

In all molluscs gastropod underwent a very important change in the evolutionary part, influence the change in shell structure. Before its shell was symmetrical coiled like garden horse but because of changes it change to central axis were coils are laid down, in order to balance out weight of the shell.

In nutshell the importance of the shell in all molluscs is to give protection to the molluscs as they are vulnerable to predators and their body are soft in such away that it cannot stand the disturbance that can involve when it moves or the environment that they can find themselves in. all class of molluscs have different shell structure depending on the place and the protection they want from predators. Molluscs that live in terrestrial have soft shell that protect it from ocean wave, while those in inland have hard shell that protect it from radiation and predators.


1. Bourquin.A.2000. The Phylum Mollusc: [internet] [cited 2006-May-4] Available from:

2. Wikipedia contributors. Aplacopra [Internet]. Wikipedia, The Free Encyclopedia; 2006 April 20, 20:04 [cited 2006 May 4]. Available from:

3. Wikipedia contributors. Polyplacophora [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 04, 15:32 [cited 2006 May 4]. Available from:

4. Wikipedia contributors. Monoplcophora [Internet]. Wikipedia, The Free Encyclopedia; 2006 April 22, 20:03 [cited 2006 May 4]. Available from:

6. Wikipedia contributors. Scaphopoda [Internet]. Wikipedia, The Free Encyclopedia; 2006 May 04, 20:07 [cited 2006 May 4]. Available from:

7. Wikipedia contributors. Gastropoda [Internet]. Wikipedia, The Free Encyclopaedia; 2006 May 04, 20:07 [cited 2006 May 4]. Available from:

Mr Elelwani Muanalo
NISL- Ecological Informatics Student
CSIR Pretoria
Tel: +27 12 841 2133
Fax: +27 12 842 7024.
My bloger URL:

Fossilisation can be referred as the set of inorganic processes which allow the remains of formerly living organisms to be preserved after its death and buried under sediment. It happen only in dead organisms, usually the hard parts can be preserved (bones, husk, shell, etc), because they can survive the alteration and disintegration or decomposition caused by atmosphere phenomena while Soft parts are rare to be fossilised this because they are vulnerable to predator and decomposition.

This process of preservation is influenced by natural processes (weathering, floods and volcanic eruption) which bury dead organisms in the surface. Some natural process cause death of the species and some of the process bury them in sediments. Volcanic eruption can cause death to many species and it can bury them on its larva, while erosion erodes all the dead particles and deposited them with other material to form sediments. Weathering which cause breaking down of rocks bury dead organisms in the particles and form sediment or rock.

Environmental condition also plays a part in perseveration of fossils this occur in the maintenance of the morphological structure of the species, if not altered by destructive agent they can keep their morphological structure. Fossilisation that happen in terrestrial environment like marine or fluvial environment are well preserved this because depositing agents act more quickly in marine environments than degrading ones. Morphological structure can be disturbed by physical changes that may involve, like flattened or distorted as sediments is hardened into rock.

Factor that influence the preservation of fossils are:

Carbonization which is known for plants where the organic matter are leached out and reduced to carbon film and the rigid organic walls are the one preserved
Sedimentation; most organisms are preserved in this process as the organism buried in mud where some of the remaining are replaced by sulphide or phosphate mineral.
Recrystalisation; this method of preservation destroy microscopic details of the shell but does not change the overall shape, so it can keep morphological structure of the species.

All this methods of preservation helps to keep evidence of unknown species that live in the past which were influential to evolution as it buries the remaining bones of dead species.

Importance of fossils in evolution is that it helps researchers Archaeologist to identify species that live in the past decades and its origin; they can be used to interpret the process of evolution by using the fossilised material.

The fossil of different species can identify the indigenous species in the area, and they also play a part in tourist attraction because some of people would like to see the indigenous creature of the past. Fossils play a part in interpreting evolution because the remaining bones or shell support the findings of the researcher and what was happening in the previous years about different species that evolve.


1. Fossilisation; [Internet] [cited 2006-May-04] Available from:
2. Fossilisation; [internet] [cited 2006-May-03] Available from:

Monday, April 10, 2006


I attend the First SAEON Graduate Student Network Workshop held on 29 March 2006.It took place at Leriba Lodge, centurion. This was my first conference in scientific nature it helps me a lots to improve my approach on research. It was interesting as it was the first conference or workshop for graduate to network.

It was started at 8:30 to16 o’clock
The main aim of the SAEON Graduates Students network was,

 To make students to know all about the SAEON
 To encourage students to do research for long term process
 To allows graduate students to interact with senior scientist
 To have broad understanding on professional scientific research.

D.r Bob Scholes is a member of Saeon technical panel, (CSIR fellow) he also leads the ecosystem process and dynamics research at CSIR Pretoria. His presentation was guiding researcher on how to prepare a professional research which can be used in a long term period.

His key focus to guide a researcher to prepare a research which indicates the place date and name of the person who offer data and the author of the data in a research to give access to people who will want to use the data in feature

Research need to be assessed and observed so that it can satisfy social need for the people (community), these because we do research to help the community to have a better living environment. These happen because there are the one who finance most of the research indirectly.

Three pillars of landscapes by D.r. Scholes .B

He mention some interesting issues when I collect a data that, I have to record a date ,place where the data was collected and the people who help me to collect a data as well as to put my name on it. For incase if the report book for saved data get loss and also if other people want to use my data in feature

To undertake a research is not a way of benefiting yourself financially and gaining recognition, a research is taken to modify the standard of living of the community for a long term goal.

Any thing that a scientist plans must be a thing for the feature, by this it means that what a researcher observes must be for a long term. And this cannot happen always or you cannot observe most of the time and every thing. So I have to organise a hierarchies which will help to measure a lot of things in a few site

Lots of method was indicated in which a way that it reduce my estimation on how to conduct a research collecting data using metadata and also sharing the data that one collect because it does not belong to one person either your are a the researcher.

In nutshell what I have learn about writing a professional research will help me in my honours and also it encourages me to undertake research that are long term goals. Attending the conference help us to understand the way of preparing a research and also it gives me a chance to network with people in different sphere of science.

Friday, April 07, 2006

Innovation are taking place in south africa that benefit the community,people at meraka institute (csir pretoria) are helping people who are not exposed to computer by offering them a outsource digital doorway computer which will help people to learn computer on their own,is for free to use this system.

Thursday, April 06, 2006

conservation of water
Have you realize that water are scarce in some part of south Africa,can it be possible for us to construct wetland that will provide ecosystem service to clean water so that we can recycle some of used water for irrigating our farms and gardens,this can help us to minimize the waste of quality water for drinking.

"let us conserve water for the feature use"

Homo Floresiensis

The involvement of H Floresiensis does not change human evolution including our lineage, because it was not our ancestor, even though it shows all human charter .this because they use all the tools that human use and floresiensis live recently it suggests that humans are more subject to evolutionary forces than we tend to think. And yet has been unknown until now suggests that there could be other surprises waiting in the human family tree.