Change Over Time

Mrs. Horn 5th Grade 1st Nine Weeks

Our Goals for This Unit

Define adaptation and identify how they help organisms survive in their environment

Identify specific types of adaptations (physical and behavioral)

Identify an organism’s environment by studying its physical features

Define fossil and explain how they show change in an environment

Explain reasons for extinction of organisms

Adaptations

What is an Adaptation

Anything that helps an organism survive in its environment

Adaptations may be physical features on an animal’s body

Adaptations may be things animals do

Structural Adaptations

Adjustments to internal or external physical features Examples: webbed feet help ducks survive in water,

snakes and other reptiles have scales that help prevent water loss in dry environments

May help protect an organism or enable it to hunt better

Examples: turtles have hard shells to protect them from predators, sharks have excellent sense of smell and sharp teeth that help them catch food

Behavioral Adaptations

An adjustment in an organism’s behavior Example: wolves travel in packs because

together they can hunt larger animals that a single wolf alone can not capture

Migration

Movement of animals to find food, reproduce in better conditions, or find a less severe climate

Birds, butterflies, fish, and mammals such as manatees migrate

Hibernation

A period of inactivity during cold weather; animal remains inactive until warmer temperatures return

Bats, snakes, bear, and frogs hibernate to escape the cold

Desert Animal Adaptations

Long eyelashes protect eyes from strong, sandy wind.

Nostrils can be closed and opened at will. During a sandstorm, the camel closes its nostrils.

Padded feet help it to walk comfortably on the soft sand.

Long legs keep its body much above the hot sand.

Toes are joined together to prevent sinking into the sand.

Hump stores excess amount of food as fat. Due to scarcity of water only few plants grow in a desert. When food is available, a camel eats plenty of it. Excess amount of food is converted into fat and is stored in the hump. It is used when food is scarce, that is why it is able to live without eating food for several days. It drinks plenty of water to recover water lost from body, when water is available. A camel can live without water for many days.

Adaptations of Grassland Animals

Strong legs help them to cover long distances in search of food.

The body color merges with the color of the dry grass (camouflage). This helps animals like the deer to escape from their enemies and animals like the lion to remain unnoticed till the prey is close enough to hunt.

They also have a keen sense of smell and sharp eyesight.

Adaptations of Cold Region Animals

The body is covered with a thick layer of hollow hair that traps air and keeps the bear warm. There is also a thick layer of fat below its skin. These features keep the bear comfortably warm even when the temperature goes below -30 degree Celsius in winter.

The polar bear is a good swimmer. This adaptation helps it to catch seal for food when ice melts in warmer months.

The polar bear also has a peculiar habit. In winter, when the weather turns extremely cold and food is difficult to find, it goes to sleep (hibernation) and wakes up only after a few months when the weather warms up. This is how the largest meat-eating land animal on Earth survives in cold conditions without food for many months.

Adaptations of Animals Living on Mountains

The body is covered with a thick growth of hair that touches the ground and this keeps the animal warm.

Yaks have more red blood cells than any other animals. This helps them to obtain enough oxygen from the air.

At some places deep holes are covered with just a thin layer of ice. Herds of yak travel on snow in a single file, carefully stepping on the footprints left by the lead yak.

Plant Adaptations

Scented flowers that attract pollinators Leaves that catch sunlight Roots that soak up water Rain-forest plants have pseudobulbs that store water Drip-tip leaves that have adapted to constant wet conditions in a rain

forest and drain excess water Cacti in the desert have thick, waxy stems that prevent water loss;

also have dense, shallow roots that soak up rain quickly Oak trees loose leaves in the winter to prevent water loss Aquatic plants’ stomata are located on the top of their leaves rather

than the bottom because the float on water Other plant adaptations include producing chemicals that taste bad

and some produce poisonous chemicals to deter predators

Evidence of Change Over Time

Fossils

Any remains, traces, or imprints of organisms that lived long ago.

How Are Fossils Formed?

Dead organism is covered by sediment the soft parts of the body decay but the

skeleton is preserved the skeletal parts are then replaced by

minerals in the sediment surrounding sediment hardens into rock

How Are Fossils Formed?

An insect may become trapped in tree sap. Over time, the sap hardens into amber and preserves the insect

An animal may walk across wet sand or soil. If the footprint is quickly covered by sediment, the footprint can be preserved.

What Fossils Tell Us

Provide clues that tell us how environments have changed

Help scientists determine the past climate of an area

Provide clues about what organisms were like in the past and how they have changed

How has Earth Changed?

Earth’s history is measured in long stretches of time called eras

Eras are described by the kinds of life that were dominant at that time

Precambrian

Earliest part of Earth’s history

Earth became hospitable to life

Paleozoic

Life became abundant Trilobites, fish, insects,

amphibians, and reptiles appeared

Many organisms became extinct at end of this era

Mesozoic

Appearance of dinosaurs, mammals, birds, and flowering plants

Rocks from the end of this period suggest that many forms of life become extinct at the end of this era

Cenozoic

Era in which we live Fossils show that early

mammals were very large

Most recent ice age occurred during this period of time or era

Test Prep

A squirrel is born with white fur instead of the normal gray fur color. How would environmental conditions have to change to increase this squirrel’s chance of survival?

A. A city dump is built nearby.B. Volcanic ash covers the forest.C. The climate gets cold enough to snow.D. An earthquake causes the land to shift.

Test Prep

An environment suddenly becomes colder. Which adaptation would MOST LIKELY give some animals a better chance of survival than others?

A. Long tailsB. Long earsC. Small eyesD. Thick fur coats

Test Prep

What adaptation would make it difficult for a brow bear to get food in a polar bear’s habitat?

A. Its brown fur

B. Its sharp claws

C. Its large body

D. Its sharp teeth