Lesson Plan

Desert Adaptations

pink flowers bloom on a cactus with long spines

NPS/Neal Herbert

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Grade Level:
Second Grade
Subject:
Biology: Animals, Biology: Plants
Duration:
30 minutes
Group Size:
Up to 36
Setting:
outdoors
National/State Standards:
Utah State Science Core Curriculum Topic: Standard 4 – Life Science: Students will gain an understanding of Life Science through the study of
changes in organisms over time and the nature of living things.
Keywords:
echolocation, seed dispersal, beak, adaptations, lizards

Overview

Students observe and compare different methods of seed dispersal. They learn about bat behavior and anatomy, and explore how a lizard's skin helps it survive. Lastly, they discover the link between the shape of a bird's beak and the food it can eat.

Objective(s)

PRE-TRIP ACTIVITY
The Desert Habitat

Objectives
Students will be able to:
a. List three characteristics of a desert environment
b. Describe two parts that can help a plant or animal survive in the desert

STATION #1
Flying Away

Objectives
Students will be able to:
a. Name two ways seeds are dispersed
b. Identify which type of seed dispersal travels the farthest in the desert
c. Understand science experiments require specific steps

STATION #2
Where Is My Dinner?

Objectives
Students will be able to:
a. Name a part bats use to find food
b. Describe how a bat's ears allow them to travel in the dark

STATION #3
Saved by My Skin

Objectives
Students will be able to:
a. List two different types of animal skin
b. Describe two ways an animal's skin helps it to survive

STATION #4
What Can I Eat?

Objectives
Students will be able to:
a.Describe how beak shape determines diet.

POST-TRIP ACTIVITY
Find My Home

Objectives
Students will be able to:
a. List one characteristic of three different local environments
b. Identify at least one plant or animal part that is suitable for a specific environment

Background

Plants sprout from seeds, grow, and produce flowers, which, if pollinated, produce more seeds. Plants need sun, soil, and water in order to make their own food and grow. Insects, hummingbirds, and bats inadvertently pollinate flowers while seeking nectar. Some plants, such as coniferous trees, rely on wind to distribute pollen.

Seeds are an adaptation that helps plants disperse and germinate effectively. A seed is made of a tough outer coating to protect the seed from the elements, a plant embryo, and a small food supply to help the young plant develop quickly. If all seeds from every plant dropped straight down and sprouted, there would be overcrowding and no means of an individual plant to spread its genes over a larger area. Seed dispersal is an adaptation for plants because it allows a plant's offspring to spread out and not compete with each other for essential resources.

There are many different mechanisms for seed dispersal, but they can be broken down into four broad categories: wind dispersal, water dispersal, externals "hitchhikers", and internal "hitchhikers". Wind-dispersed seeds are often very light and have a large surface area or cotton-like "puff' to help them catch the wind and travel. Cottonwood "puffs" and maple "helicopters" are two very common wind-dispersed seeds. Water-dispersed seeds often have a seed coat that is very light and porous to add buoyancy to the seed and help it float on waves or currents. For example, the outer husk of a coconut is very light and helps it float in the ocean.

"Hitchhiker" seeds are seeds that rely on animals for dispersal. External hitchikers usually have hooks, spines, or sticky substances to help them attach to an animal as it brushes by the parent plant. After a while, the seed will fall often, often miles from the parent plant. Instead of relying on animals to brush against them, plants with internal hitchhiker seeds actively try to get animals to eat their seeds by enclosing them in a nutritious, good-tasting fruit. Inside the animal's body, the outer fruit is digested, but the seeds are untouched. When the animal eliminates its solid waste, the seeds are dropped miles away from the parent plant and have a pile of natural fertilizer to help them grow. Camouflage is a way of blending into the environment so an animal is not noticed. Camouflage does not make an animal invisible, but effectively hides it in plain sight. Camouflage is often thought of as green blotches, but more often the color and pattern of an animal's fur often reflects the environment the animal lives in. For example, the stripes on a zebra help it blend in to the similarly patterned grasses and shadows of the savannah it lives in. In the desert many animals are brown to blend into the brownish-red sand and rocks.

Mammals are endotherms, or warm-blooded, meaning they generate their own heat. In addition to skin, all mammals also have the adaptation of an outer layer offur or hair. Many have two layers of fur that covers all of their body. The downy under hair or ground coat is a dense layer of short curly hairs. The guard hair is a layer of long course hairs that protect the under layer. It is often water repellent and gives the animal its distinctive color. Fur has serves as insulation, especially in animals that live in cold environments.

Rather than generating heat, fur traps heat that is generated by a mammal's metabolism, keeping the animal warm. It is much like how humans use thick blankets and clothes to trap our own body heat to stay warm. Many animals shed excess fur in the spring to prepare for hot summer temperatures and grow extra fur in the fall to prepare for cold winter temperatures. Fur also does a number of other things for mammals. It protects the skin from sun and abrasion, sends sensory messages to the brain, and provides insulation from cold and heat. Pigments in the inner layers of hair filter harmful ultraviolet radiation just like sunscreen, and may help regulate body temperature. Dark hairs absorb heat, warming an animal, while light colors reflect sun, keeping an animal cooler.

The beak or bill on a bird is used for many things including eating, grooming, feeding young, manipulating objects, fighting or courtship. Although all beaks differ in size and shape each consists of two bones, the upper and lower mandible, covered in a thin sheath known as the rhamphotheca. Some species of birds also have nasal holes in their beak. Much like teeth, beaks are diverse and well-adapted to a bird's environment and food choice. Seed eaters like sparrows and cardinals have short, thick conical bills for cracking seed. Birds of prey like hawks and owls have sharp, curved bills for tearing meat. Woodpeckers have bills that are long and chisel-like for boring into wood to eat insects. Hummingbird bills are long and slender for probing flowers for nectar. Birds like herons and kingfishers have spear-like bills adapted for fishing. Insect eaters like warblers have thin, tweezer-like pointed bills.

Bats are small, flying rodents that are mostly nocturnal. Unlike bird wings, which are mostly made from specially adapted arm bones, bat wings are specially adapted hands with a membrane connecting the "fingers". Bats are the only mammal capable of sustained flight. 70 percent of bats species including all the bats in Utah eat insects. Of the rest, most eat fruits although there are some that eat fish and vampire bats are parasitic to other mammals. Bats are nocturnal animals. They sleep during the day in shelters such as caves or empty buildings. This enables them to hide from predators while they are asleep and vulnerable.

Another adaptation unique to some bats is echolocation, an ability that helps bats navigate and find food in the dark. Echolocation is based on the principle of an echo. An echo is created when sound waves bounce off an object and are received by an animal's ears. Humans can create echoes by yelling against a canyon wall. Bats are constantly creating echoes by sending out ultrasonic pulses through its nose and mouth. These pulses can be as fast as 500 per second and are too high pitched for humans to hear. These sound waves bounce off of both in sects and other features in the environment (trees, rocks, etc.). When the bats hear these echoes, they are able to tell the location of the object the waves bounced off of. If it bounced off an in sect, they can chase it for food. Bats are constantly "scanning" their environment through echolocation. Once they recognize an insect, they dramatically in crease how often they chirp to gather more detail about the location of the in sect. lf a chirp bounces off an object, they know to avoid it while flying.

Procedure

Extensions

POST-TRIP ACTIVITY
Find My Home

Have students return to their desk and split the class in half. Tell one side that they are tadpoles and the other side that they are adult frogs. When you hold up a description of a body part or environment that their side uses (i.e. a long tail = tadpoles, dry land = adult) everyone on that side should raise their hand. Vary between pictures and descriptions for tadpoles, adult frogs and examples that neither has/needs.

Additional Resources

Amazing Mammals Part II. (1986). Ranger Rick's NatureScope. Washington, DC: National Wildlife Federation.

Birds, Birds Birds. (1989). Ranger Rick's NatureScope. Washington, DC: National Wildlife Federation.

Lingelbach, J. (Ed.). (1986). Hands-on-nature: Information and activities for exploring the environment with children. Woodstock, VT: Vermont Institute of Natural Science.

Project WILD: K-12 activity guide. (2nd ed). (1992). Bethesda, MD: Council for Environmental Education.

Strauss, K. (2006). Tales with Tails: Storytelling the Wonders of the Natural World. Westport, CT: Libraries Unlimited.

Last updated: December 28, 2017