Archive for March, 2012



Look for info in the net, for example here:

Try this  Evolution game and then watch this video  Teacher’s Guide to: Evolutionary theory and answer the quiz questions.

Watch:

After that  visit an read  some of these ppts:

Or the ones in biodeluna tagged as Evolution.

and answer these questions:

  1. What did Darwin noticed thanks to the Beagle voyage?
  2. Write the main points of Lamarckian evolution theory.
  3. Write the main points of Darwinian evolution theory.
  4. When did he do this voyage? How old was he by then?
  5. Explain the key he found in finches to propose his theory
  6. When did he publish the book presenting his theory of evolution? What was the title of this book?
  7. What are homologous organs? Giveanexample.And analogous organs?
  8. Write a list with Darwin´s evidences to support evolution´s theory.
  9. Who thought of a very similar theory to Darwin´s one at the same time?
  10. Find out what is “Co-Evolution” and give an example.
  11. What is meant by neodarwinism?

Send your answers as soon as you got them to my email.

DEADLINE- Monday 9th April

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Polar Bear Adaptation

This is my post about the adaptation of a polar bear. Hope you like it!

A. Swimming.

1. Polar bears are strong swimmers; they swim across bays or wide leads without hesitation. They can swim for several hours at a time over long distances. They’ve been tracked swimming continuously for 100 km (62 mi.) (Stirling, 1988).

2. A polar bear’s front paws propel them through the water dog-paddle style. The hind feet and legs are held flat and are used as rudders.

3. A thick layer of blubber (fat), up to 11 cm (4.3 in.) thick, keeps the polar bear warm while swimming in cold water (Stirling, 1988).

4. Polar bears can obtain a swimming speed of 10 kph (6.2 mph) (Stirling, 1988).

5. The hair of a polar bear easily shakes free of water and any ice that may form after swimming.

6. A polar bear’s nostrils close when under water.

A polar bear’s front paws propel it through the water dog-paddle style. The hind feet and legs are held flat and are used as rudders.

B. Diving.

1. Polar bears make shallow dives when stalking prey, navigating ice floes, or searching for kelp.

2. Polar bears usually swim under water at depths of only about 3 to 4.5 m (9.8-14.8 ft.). They can remain submerged for as long as two minutes (Domico, 1988).

3. No one knows how deep a polar bear can dive. One researcher estimates that polar bears dive no deeper than 6 m (20 ft.).

C. Thermoregulation.

1. Body temperature, which is normally 37C (98.6F), is maintained through a thick layer of fur, a tough hide, and an insulating layer of blubber. This excellent insulation keeps a polar bear warm even when air temperatures drop to -37C (-34F) (Stirling, 1988).

2. Overheating.

a. Polar bears are so well insulated they tend to overheat.

b. Polar bears move slowly and rest often to avoid overheating.

c. Excess heat is released from the body through areas where fur is absent or blood vessels are close to the skin. These areas include the muzzle, nose, ears, footpads, inner thighs, and shoulders.

d. Polar bears will also swim to cool down on warm days or after physical activity.

underwater swimming

Bibliography: I took the information from this webpage–>http://www.seaworld.org/infobooks/polarbears/pbadaptations.html

The adaptation of the Walrus

One of the adaptations for the cold od the walrus is that they don’t ave external ears, so that make no cold.

Their rounded streamlined body makes them well adapted for swimming and to conserve heat.

They have a large percentage of blood in their bodies to carry oxigen, their red blood cells are exceptionally large, they have lots of myoglobin in their muscles that can store oxigen.

All of these things, are adaptations allow for an efficient and lenghty use of oxygen store.

Antipredator Adaptation

 

 

 

The act of a predator acquiring a food source can be divided into four stages: detection, attack, capture and consumption.At every stage in this predatory sequence, adaptations that maximize the prey’s chance of survival have evolved. This, in turn, has driven adaptation in their predators. This kind of interaction over long periods is known as co-evolution.

Many predatory animals are themselves preyed upon. To defend themselves, predatory animals often use their methods of attacking prey to inflict or threaten grievous injury to their own predators. For example, the electric eel uses the same electrical currents to kill prey, and to defend itself against predators (such as anacondas, caimans, jaguars, egrets, cougars) which prey on fish of similar size to the eels

In 2001 2.3 % of the world’s population, or 140 million people, were living at high altitude. This is defined as people who reside permanently above 2500m or 8000 feet. These people live in four main areas. Firstly there are the residents of the Tibetan Plateau, both the indigenous Tibetans who are estimated to have been living there for between 7,000 and 50,000 years and the Han Chinese who have migrated to the plateau in the last century. Secondly are the residents of the Andes mountain range in South America who are estimated to have been living there for 10,000 years. Thirdly are the less studied Ethiopian population and finally are the Europeans who have been living in the Colorado Mountains in North America for the past 150 years.

The environmental stress of high altitude is hypoxia that, in turn, creates the conditions for physiological hypoxia (less than the normal amount of oxygen in the organism).

At 4,000-m elevation, every breath of air contains only ≈60% of the oxygen molecules in the same breath at sea level. This is a constant feature of the ambient environment to which every person at a given altitude is inexorably exposed. Less oxygen in inspired air results in less oxygen to diffuse into the bloodstream to be carried to the cells for oxygen-requiring energy-producing metabolism in the mitochondria. Humans do not store oxygen, because it reacts so rapidly and destructively with other molecules. Therefore, oxygen must be supplied, without interruption, to the mitochondria and to the ≥1,000 oxygen-requiring enzymatic reactions in various cells and tissues.

There are several kind of adaptations that have been acquired by these populations along the time:

Energy Production. Andean and Tibetan highlanders display the standard low-altitude range of oxygen delivery from minimal to maximal. Both populations have the normal basal metabolic rate expected for their age, sex, and body weight, implying that their functional adaptations do not entail increased basal oxygen requirements. Thus, they can use at high altitude the same full range of aerobic potential for activities requiring oxygen

delivery that others use at low altitude. This represents a functional change from the ancestral acute response to altitude, and it suggests that the high-altitude native populations have adaptations that do not elicit elevated oxygen consumption.

Oxygen in the Bloodstream. Another potential adaptation is a higher concentration of hemoglobin. However, Tibetans have lower hemoglobin concentrations than the Andeans at the same altitude.

Together, oxygen saturation and hemoglobin concentration determine arterial oxygen content. On average, neither Andean nor Tibetan highlanders restore the usual sea-level arterial oxygen content. Instead, Andean highlanders have overcompensated for ambient hypoxia according to this measure, whereas Tibetan highlanders have undercompensated.

Blood Flow and Oxygen Diffusion. Other potential points of functional adaptation include the rate of flow of oxygen-carrying blood to tissues and the rate of oxygen diffusion from the bloodstream into cells.

Tibetans do not have hypoxic pulmonary vasoconstriction or pulmonary hypertension. Andean highlanders are consistently reported to have pulmonary hypertension, and bigger pulmonary capacity, being their torsos wider with the object to hold the lungs. A probable reason for the normal pulmonary artery pressure among Tibetans is high levels of the vasodilator nitric oxide (NO) gas synthesized in the lining of the blood vessels. In contrast, NO is substantially elevated in the lungs of Tibetan as compared with Andean highlanders and lowlanders at sea level.

 

 

Alfonso de Castro

Every animal has to adapt itself physically and behaviorally to survive in a particular environment. African lions have also struggled for several years to develop adaptations that have helped them to survive in the long run. African lion adaptations can be divided into two categories – Physical adaptations and Behavioral adaptations. Structural modifications in the body fall under physical adaptations, while reactions of the animal in response to an external stimuli come under behavioral adaptations. So let’s have a look at the adaptations these wild African cats have developed to live on, in the savannas.

 

Physical Adaptations of African Lions

Sharp Claws
Large and sharp claws is one of the best adaptations of African lions. They use their sharp claws to kill their prey and tear meat from the prey’s body, after it has been killed. Sharp claws are also used for defense and to display their strength and power to other animals. This also helps in keeping predators and competitors away. Claws also provide the required grip to lions so that they can easily gain speed while running.

Sharp Teeth
The most visible and striking adaptation in an African lion is its sharp teeth. Like other carnivores, lions also rely on meat to meet their dietary requirements. Dull teeth are not capable for providing the grip to tear and chew meat, that is why, lions have sharp teeth so that they do not have any problem in eating food. Another use of sharp teeth is defense. In case of a fight, teeth help lions to defend themselves and survive.

Whiskers
This is an adaptation which helps African lions to feel. Whiskers act as feelers and allows the animal to sense its surroundings, and find its way out through tight spots. When a lion is on a hunt, these whiskers help it to sense the prey. These also help in sensing whether it can fit into a particular area or not.

Tan Fur Color
African lions have tan-colored fur on their body. This fur color is an adaptation to meet certain requirements. The tan color helps the lion to blend with the color of the surroundings which prevents it from being attacked by predators and competitors, and also helps it sneak through while preying. If the color of the fur was different, then it would have been difficult for lions to survive attacks and find food for themselves.

Behavioral Adaptations of African Lions

Vocalizations
This is a behavioral adaptation African lions have developed to communicate within their group. Lions hum when they are content and make a puffing sound when they approach each other with good intentions. Grunting is a sound they produce to keep in touch when they are moving from one area to the other. Finally comes the roaring, we are all very well familiar with. Females roar to protect their cubs from other animals or when they call other females to help defend intruders. Males roar to specify their location, display their strength, and signal other animals to stay away from the pride.

Nocturnal Hunting
African lions are nocturnal and prefer to hunt in the darkness of the night. They often hunt for food in groups and females do all the hunting. The strength of the group is generally determined by the amount of food the pride has. Another reason for hunting during the night is that lions get tired very quickly due to their muscular body. That is why they spend nearly 20 hours of a day resting. Hunting at night provides them relief from heat during the day.

Family Life
A pride has several mothers giving birth to young ones. Mothers take care of their cubs and keep them hidden from other animals for about eight weeks, as they cannot take care of themselves. Nursing mothers form groups, and take care of other cubs as well in their mother’s absence. Mothers who give birth to only one cub willingly nurse other cubs because they produce enough milk to feed them. In tough situations, when the pride does not have enough food, mothers abandon their cubs and move ahead. This is done so that females remain within the pride and can again give birth to young ones at times when the pride has enough food for all its members.

Taking Lessons
Like human beings, African lions teach their young ones ways to live and survive. By the time a cub is three months old, the mother teaches it ways to hunt for food. The young cub observes adult members of the family and learns to look for and hunt its prey. When a cub is one year old, it starts hunting, even though it does not have expertise in it. Cubs become an expert at hunting only after they are 2-3 years old. Once the cubs are 2 years old, the male cubs are forced to move out of the pride and find a new pride for themselves. Females are allowed to stay in the group to have their own cubs in the future.

Two cute kittens of white lion

Two kittens of white lion. This type of lion have white fur because a recessive gene.

 

camels

Adaptation: Two rows of long eyelashes

Function: Protect against blowing sand and the sun

Adaptation: Nostrils can be closed

Function: Keep out blowing sand

Adaptation: Fat stored in hump(s)

Function: Help it to survive long periods without food and water

Adaptation: Thick fur and underwool

Function: Provide warmth during cold desert nights and insulation against daytime heat

Adaptation: Thick leathery patches on knees

Function: Protect it from getting burn when it kneels on the hot desert sand

Adaptation: Long strong legs

Function: Help carry heavy loads over long distances and keep its body further away from the hot sand

Adaptation: Broad, flat, leathery pads at the bottom of their hooves

Function: Pads spread out when the camel places its feet on the ground thus creating a “snowshoe effect” and preventing the camel from sinking into the sand

Penguin

They live in the southern hemisphere .

They have wings but they can´t fly. The wings are use like flippers that make them move quickly in the water. (they look like they fly in the water)

ImageIt has a smooth plumage and under it a layer of air that helps to insulate from the cold waters.

Also they use camouflage because the animals below their in the water don´t distinguish them.

And they have an average sense of hearing for birds.

Image

 

Chameleon’s adaptation

Chameleon have three basics adaptation:

1-Chameleon’s skin pigment cells can change color depending on temperature, mood, and during breeding. Basically they communicate with other chameleons through slight color changes.

2-Their eyes are independent so they can move them any direction. This adaptation can help them to see what’s going on around it.It can also help them to look out for predators, because they can’t run very fast.

3-They have a long tongue about the length of their body. It has a sticky substance at the end so the chameleon can get his/her prey in an instant. It is useful to catch their prey fast so its prey will not escape. It’s tongue can shoot so fast, the human eye can hardly see it. The chameleon has a long tail that acts as fifth arm. When it is no use the tail is all coiled up. Its tail is can be very useful because it can balance on a thin branch, its tail also can help it to stay very still.

DOLPHIN´S ADAPTATION

The Dolphin is a mammal that had been livig in the sea since fifty millions years ago. This mammals had adapt with a hydrodinamic form that makes easiest and faster to move through the water. Another thing that makes easiest their movement thorugh water is that their tips are fins. Although they live in water they need to breath to survive and the adaptation is that the hole for breath is in the top of them so it is easier to breath for them.