Human Hand Adaptations

 

Human Hand Adaptation

Introduction:        Living things have bodies that are adapted for the places they live and the things they do. Fish have gills so that they can remove oxygen that is dissolved in water. Most plants have green leaves which contain chlorophyll so that they can make food. Jellyfish have stinging cells to capture prey. Birds have hollow spongy bones so that they will be light enough to fly. Arctic animals have layers of fat and thick coats of fur to keep warm in the frigid Arctic climate. There are hundreds of examples of ways that organisms are adapted for a successful lifestyle.       Humans, too, are adapted for the things they do. One of our adaptations is our hand. Humans, as well as monkeys, gorillas, and other primates, have a hand that can grasp objects. We are able to grasp objects because of our opposable thumb. When students first hear or read about the opposable thumb during discussions of human evolution, they may perceive it as an anatomical fact with little seeming importance. In this activity, students will discover which of their simplest daily activities are possible only because of their opposable thumbs, which activities take longer without the use of an opposable thumb, and what sort of human activities would not be likely in the absence of an opposable thumb.   In this lab exercise, you will perform several common actions. Then you will change your hand so that it resembles that of a non-primate animal. You will determine whether or not you can successfully perform the same actions. This will demonstrate how the human hand is adapted for the actions it performs. You will work with a partner to do this exercise.   Materials: (per group)

  • masking tape
  • scissors
  • paper clips
  • zip-lock storage bag
  • plastic fork and knife
  • small amounts of food items to be cut
  • pencil
  • jar with screw-on lid
  • paper
  • roll of tape
  • balloons
  • comb
  • book
  • lace-up shoe
  • clock with a second hand
  • Piece of yarn or string
  • balloon
  • clothes with zippers & buttons

Procedure: Using masking tape, have your partner tightly tape each of your thumbs to the palm of the hand. Then, try to complete the tasks that are listed below. Be careful not to use your thumbs. Have your partner record on your data table how long it takes to do each task with your thumb taped and then with your thumb free. If an activity takes longer than 2 minutes, record the event as unsuccessful . After completing each item, write out the answers to the following questions:

  • Is the task more difficult with or without an opposable thumb?
  • How did you have to change your usual technique in order to complete this task?
  • Do you think organisms without opposable thumbs would carry out this task on a regular basis? Why or why not?

Tasks:

  1. Pick up a single piece of paper. Put it down on your desk.
  2. Pick up a pen or pencil from the table top. Use it to write your name on the piece of paper.
  3. Open a book. Turn single pages in the book.
  4. Unscrew a bottle cap or jar cover.
  5. Use a fork and knife to cut a food item into small pieces.
  6. Tear off a small piece of tape.
  7. Turn on the water faucet. (Complete activity #8!) Turn it off.
  8. Moisten a paper towel and wash and dry the desktop.
  9. Sharpen a pencil.
  10. Cut a circle out of a piece of paper using scissors.
  11. Pick up all the scraps from activity #10 and throw them into the recycling box.
  12. Comb your hair.
  13. Open a door.
  14. Pick up one paper clip. Clip a pile of papers together.
  15. Tie your shoelaces.
  16. Button several buttons.
  17. Zip up your jacket.
  18. Blow up a balloon and tie it.
  19. Tie a knot in a piece of string.
  20. Close a zip-lock bag.

Data:

Table 1 – Time It Took To Perform Various Tasks

 

Task Time Taken for Event: Task Difficulty With Taped Thumb
(More/Less)
Modification Made to complete Task
Thumb Free Thumb Taped
Pick up paper
Write name
Turn book pages
Open jar
Use knife & fork
Tear off tape
Turn faucet on & off
Clean desk top
Sharpen a pencil
Cut out a circle
Pick up the scraps of paper
Comb hair
Open door
Clip papers together
Tie shoelaces
Button & unbutton garment
Use zipper
Blow up & tie balloon
Knot string
Close zip-lock bag

Conclusion:   1. Explain why dog and cat paws are not adapted for doing the six actions you tested.     2. What are cat and dog paws adapted for?     3. Describe how your hand is adapted for doing the actions you tested.       4. You have an opposable thumb. Explain what this means.     5. Why do you feel that human hand adaptations have helped to make humans such a successful species on earth?

 

Identifying Controls and Variables

Identifying Controls and Variables

 

Smithers thinks that a special juice will increase the productivity of workers. He creates two groups of 50 workers each and assigns each group the same task (in this case, they’re supposed to staple a set of papers). Group A is given the special juice to drink while they work. Group B is not given the special juice. After an hour, Smithers counts how many stacks of papers each group has made. Group A made 1,587 stacks, Group B made 2,113 stacks.

 

Identify the:

1. Control Group

2. Independent Variable

3. Dependent Variable

4. What should Smithers’ conclusion be?

 

5. How could this experiment be improved?

Homer notices that his shower is covered in a strange green slime. His friend Barney tells him that coconut juice will get rid of the green slime. Homer decides to check this out by spraying half of the shower with coconut juice. He sprays the other half of the shower with water. After 3 days of “treatment” there is no change in the appearance of the green slime on either side of the shower.

 

6. What was the initial observation?

Identify the-
7. Control Group

8. Independent Variable

9. Dependent Variable

10. What should Homer’s conclusion be?

 

 

 

Bart believes that mice exposed to microwaves will become extra strong (maybe he’s been reading too much Radioactive Man). He decides to perform this experiment by placing 10 mice in a microwave for 10 seconds. He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. he found that 8 out of 10 of the micro waved mice were able to push the block away. 7 out of 10 of the non-micro waved mice were able to do the same. Identify the-
11. Control Group12. Independent Variable

13. Dependent Variable

14. What should Bart’s conclusion be?

15. How could Bart’s experiment be improved?

Krusty was told that a certain itching powder was the newest best thing on the market, it even claims to cause 50% longer lasting itches. Interested in this product, he buys the itching powder and compares it to his usual product. One test subject (A) is sprinkled with the original itching powder, and another test subject (B) was sprinkled with the Experimental itching powder. Subject A reported having itches for 30 minutes. Subject B reported to have itches for 45 minutes. Identify the-
16. Control Group17. Independent Variable

18. Dependent Variable

19. Explain whether the data supports the advertisements claims about its product.

Lisa is working on a science project. Her task is to answer the question: “Does Rogooti (which is a commercial hair product) affect the speed of hair growth”. Her family is willing to volunteer for the experiment.

20. Describe how Lisa would perform this experiment. Identify the control group, and the independent and dependent variables in your description.

 

 

Ink Chromatography

Chromatography of Inks

Introduction:

One of the main jobs of biochemists is to unravel the complexities of chemical compounds and reduce them to their individual components.  The term chromatography comes from two Greek words, “chromat” meaning color and the word “graphon” meaning to write.  Separation of the components of chemical compounds can be done by using several methods. Liquids can be separate by High Performance liquid Chromatography (HPLC), while the components of gases are separated by Gas Chromatography.  Chromatography is a method for analyzing complex mixtures (such as ink) by separating them into the chemicals from which they are made. Chromatography is used to separate and identify all sorts of substances in police work. Drugs from narcotics to aspirin can be identified in urine and blood samples, often with the aid of chromatography.

Chromatography was first used to separate pigments (colors) in leaves, berries, and natural dyes. Paper chromatography is a technique used to separate, isolate, and identify chemical components of a compound. In paper chromatography, the solid surface is the cellulose fibers in the chromatography paper.  A solvent or developer (water, alcohol, or acetone) is placed in the bottom of the chromatography chamber. The paper acts as a wick to pull the solvent up the paper. The solvent front will “wick” up the chromatography paper by capillary action.  A minute drop of the ink or chemical mixture to be separated is placed near the bottom of the strip of chromatography paper, but slightly above the level of the solvent in the chamber.  As the solvent passes over the drop of ink, the components of the ink dissolve in the solvent. Because the components of the ink do not all dissolve at the same rate, as the components of the mixture move upward, they show up as colored streaks.  The separated substances on the chromatography paper form a color pattern called a chromatogram.

To determine the rate of migration for each pigment or component of the ink, the Rf value for each pigment must be calculated. The Rf value represents the ratio of the distance a pigment moved on the chromatogram relative to the  distance the solvent front moved. Each pigment or compound will have a unique Rf value that scientists can use to identify the substance. The Rf value is calculated using the following formula:

Rf = distance traveled by the compound / distance traveled by the solvent

Objective:

Use the process of paper chromatography to separate the pigments in various markers and then determine the Rf value for each color on your chromatogram.

Materials:

Plastic vials, paper clips, markers in assorted colors, chromatography paper, scissors, pencil

Procedure:

  1. Obtain chromatography vials and chromatography strips, and different color markers so that each person in the group will have two chromatograms.
  2. Cut one end of the chromatography strip to a point. The bottom of the point will mark the starting point for movement of the solvent (H2O).
  3. About 2.0 centimeters from the bottom of the strip, draw a faint horizontal line with pencil. This will mark the starting point for measuring the migration distance of each color.
  4. Using a different color marker for each strip, drop a dot of ink on the center of the horizontal pencil line.  Let this dry a moment & then add more ink to the dot.
  5. Add a small amount of water to the bottom of the chromatography chamber. (The ink dot should be ABOVE the surface of the water.)
  6. Straighten a paper clip and poke a hole through the top of your chromatography strip
  7. Use the paper clip to hang the strip in your chamber. (The straighten paper clip will lay across the top of the chamber.)
  8. MAKE SURE THE TIP OF THE STRIP BUT NOT THE INK IS IMMERSED IN THE WATER!
  9. Notice the separation of the ink as both the solvent and ink travel up the chromatography strip.
  10. Once the solvent front has neared the top of the strip, remove the strip from the chamber and lay it on a piece of paper towel.
  11. Immediately mark the solvent front with a faint pencil line.
  12. Immediately mark the leading edge of each color with an “x”.
  13. Measure, in millimeters, the distance the solvent migrated from the tip of the strip to your solvent front pencil line.
  14. Measure, in millimeters, the distance each color migrated from the point of origin (pencil line where the ink dot was placed) to the leading edge of the color (marked with an “x”.
  15. Record all data in Data table 1.
  16. Calculate and record the Rf value for each color using the formula below.

Rf = distance traveled by the compound / distance traveled by the solvent

Data Table 1

 

Color pen/marker used:

Separated colors
(list top of strip to bottom)
Distance each color traveled

(mm)

Distance solvent (H2O)
(mm)
Rf Value for each color

(Distance color traveled / Distance solvent traveled)

       
       
       
       
       
       
       
       

 

 

 

Color pen/marker used:

Separated colors
(list top of strip to bottom)
Distance each color traveled

(mm)

Distance solvent (H2O)
(mm)
Rf Value for each color

(Distance color traveled / Distance solvent traveled)

       
       
       
       
       
       
       
       

 

 

Questions:

1. Which color of marker did you use?

2. which color separated out first from your ink dot?

3. Why did the inks separate?

 

4. What was your solvent?

5. If you had used markers that weren’t water-soluble, how would you have had to change this lab?

 

6. Why did some inks move a greater distance than others?

 

7. How do scientists use paper chromatography in their investigations?

 

 

Insect Collection

Insect Collection
click here for Microsoft Word copy

Insects are invertebrates with three pairs of legs, usually  two pairs of wings, one pair of antenna, jointed appendages, and three distinct body regions — head, thorax, & abdomen. Insects belong to the largest phylum of animals known as arthropods.  Many small arthropods are mistaken for insects such as spiders, ticks, millipedes, & centipedes. Although some insects may sting or bite, insects play an important role in nature as a food source for other animals and  as plant pollinators.  

By doing an insect collection, you can, not only learn beneficial and harmful insects common to your area, but you will also learn structural modifications of various insects that have enabled them to survive & become such a successful and diverse group of animals..   You will also learn to use taxonomic keys to identify organisms.   

     In order to properly do an insect collection, several techniques must be learned including how to correctly collect, kill, pin, spread, label, and display your organisms.  The following instructions have been modified for a high school biology classroom.

Insect Orders PowerPoint

Materials needed for collecting:

  • insect net
  • several kill jars with killing agent (nail polish remover works)
  • notebook
  • pencil
  • tweezers
  • several clean baby food jars (these will be holding jars)
  • equipment bag

Good Web sites for identifying Insects:

Bug Guide 

Insect Identification 

Key to Ten Insect Orders

North American Insects

How to make an insect net:      

  1. Bend the triangular part of a wire coat hanger until it forms a circle.
  2. Carefully straighten the wire hook. (A)
  3. Untwist the “neck”. (B)
  4. Sew netting, cheesecloth, or sheer curtain material to form a bag with a tapering end.
  5. Sew a hem at the top end of the bag leaving an opening for the wire hanger.
  6. Thread the wire hanger through the hem of your bag & then twist the wires together.
  7. Use plenty of heavy gray tape to tape the twisted wire securely to the end of a broom handle or wooden dowel.

How to make a kill jar:
(YOU NEED A SEPARATE JAR FOR BUTTERFLIES & MOTHS SO MAKE 2 JARS)

  1. Use a clean, glass or plastic jar with STRAIGHT SIDES.
  2. Write a poison label and tape this to the front of the jar with clear tape. (KEEP THIS JAR AWAY FROM SMALL CHILDRREN)
  3. Tape the bottom of glass jars with heavy gray tape to protect them from breaking if they are dropped.
  4. Place a 2″ – 3″ layer of cotton balls in the bottom of the jar.
  5. Cut a piece of corrugated cardboard the same diameter as the inside of the jar to fit over the cotton balls.
  6. Carefully punch several small holes in the cardboard with an ice pick.
  7. Charge the jar by adding polish remover to the cotton balls.
  8. Immediately place the cardboard circle on top of the cotton balls & PLACE THE LID ON THE JAR. (ONLY REMOVE THE LID TO ADD OR REMOVE INSECTS!)
  9. Keep the inside of the jar moisture free so insects won’t discolor & replace the cotton & cardboard as needed.
  10. DO NOT STORE DEAD INSECTS IN YOUR JAR AS THEY WILL DECAY & SMELL!!!!!
  11. READ PINNING INSTRUCTIONS & PIN INSECTS AS SOON AS THEY ARE DEAD!!!

https://biologyjunction.com/images/6892f011.gif     http://extension.entm.purdue.edu/401Book/images/collect/fig7.jpg

Remember to  RECHARGE THE JAR PERIODICALLY if insects do not seem to be dying as fast and NEVER LEAVE THE LID OFF OF YOUR JAR!.

Collecting: 

    Insects are found almost everywhere so look for them on plants, in water, in soil, under rocks, in rotten logs, around lights at night, etc.  Your collection will consist of 20 insects for Biology I and 30 insects for Pre-AP Biology.  Collect only adults in perfect condition to receive credit. As you collect insects, be sure to record the name of the insect or a good description, the date collected, and the place each insect was collected in your notebook. Use different kill jars for butterflies and beetles and never put too many insects in the same kill jar.   Once your insect is dead (not just knocked out), use tweezers to transfer them to a small  baby food jar until you arrive home to pin it.  Don’t leave the insects in these holding jars more than a few hours and never leave insects in kill jars more than 3 to 5 hours because of their brittle bodies.  most insects will die within 30 minutes to one hour in a charged newly charged kill jar.

    When collecting stinging insects, invert the net once the insect is captured and allow the insect to crawl to the tapered end of the net. Carefully grasp the net above this tapered end,  open the kill jar, and put the tapered end of the net with the insect inside the jar. Lay the lid back on top of the jar until the insect is “knocked out”.  Remove the lid and lift out the net with the unconscious insect. Turn the net back over, shake the insect  into the jar, & replace the lid until the insect finishes dying.  If you are allergic to certain insect stings, have another student collect this insect for you.  

Materials for mounting & labeling:

  • tweezers
  • Elmer’s glue
  • insects pins
  • card points
  • insect labels
  • spreading board
  • pinning block (optional)
  • straight pins
  • index cards
  • scissors
  • black ink pin
  • pencil
  • several small vials
  • shoebox with Styrofoam in the bottom
  • notebook
  • paper towels

Pinning insects: 

See your insect notebook for pictures of the proper placement of insect pins through the body of different orders of insects.

  1. Hold the insects by its sides using your thumb & forefinger and firmly push the insect pin through the dorsal or top surface of the insect. The pin should be at a right angle to the insect’s body.
  2. The insect should be LEVEL on the pin with just enough pin extending above the top of the insect so you can now handle the pin and not the insect
  • Beetles are pinned near the front margin of the right wing near the midline
  • Grasshoppers are pinned to the right of the prothorax
  • True bugs are pinned to the right of the scutellum
  • Butterflies, moths, dragonflies, & damselflies are pinned through the middle of the thorax
  • Most other insects are pinned through the thorax to the right of the midline

  1. Place insects on insect pins so their body is horizontal to the pinning surface or Styrofoam.
  2. Gently push the insect within at least 25mm from the top of the pin so that you can pick up the pin without touching the insect.  Make sure all pinned and card pointed insects in your collection are at the same height on the pin.  Two labels will be added below the insect’s body later.
  3. If the abdomen sags, place a small piece of index card below the body on the pin until the insect’s body dries and then remove the card.
  4. Insects with extremely long legs like crane flies or curved antenna & abdomens like ichneumon wasps should be placed on their left side and pinned through the right side of their body in the area of the thorax.

OOPS!  My insects got too dry to pin or How to relax insects: 

It is always wise to pin insects the same day that you collect them because if they dry completely, then they must be relaxed before pinning.

  1. Use a plastic container with a tight fitting lid, and add a layer of sand to the bottom of the container.
  2. Moisten the sand and small amount of bleach or carbolic acid to prevent molding.
  3. Place a paper towel on top of the sand and lay insects on the towel.
  4. Replace the lid and allow to re-hydrate for 1-3 days.
  5. Insects without hairy or scaly coverings such as beetles & grasshoppers, may be dropped into hot (just simmering) water for a few moments to relax them.  If specimens are left in the water too long they will ruin!

What do I do with insects too soft to pin? 

  1. All soft bodied insects such as mayflies, aphids, lice, & termites along with fleas must be kept permanently in preserving fluid in vials.
  2. Use clear, glass vials with tight fitting lids.
  3. Place only one type of insect in each vial and add enough alcohol to cover the insect and the identification labels which will be place inside the vial.
  4. Write vial labels in pencil, not ink!
  5. Place the blank sides of the 2 labels together before dropping them down into the vial so they can be read more easily.

What if the insect is too small to pin & not soft bodied? (card pointing):

  1. Insects too small to be pinned should be mounted on a card point.
  2. Card points are small triangular pieces of white cardboard through which a #3 insect pin is placed.
  3. Points are made using a point punch.  Obtain these points from your teacher.
  4. Lay specimens to be mounted on their left side on paper towel.  The insect’s right side should be up towards you!
  5. Place a # 3 pin through the broad end of a card point.  This is easier if you lay the point on a plastic lid so it doesn’t bend when you thrust the pin through the card point!
  6. Use tweezers to bend the very tip of the card point downwards.
  7. Place a small amount of Elmer’s glue on the paper towel and then touch the bent tip of the point to the glue.
  8. Touch and hold this bent tip with its glue to the right side of the thorax of your insect.  Hold the tip to the insect for at least one minute.
  9. Set the pin up into Styrofoam making sure the glue is dry & the insect’s body is parallel to the pinning surface.

Spreading butterfly & moth wings:  

To prevent butterflies & moths from drying out before wing spreading, place them in small plastic bowls in the freezer.  Be sure to tell your mom!

  1. Wings of butterflies and moths are spread to show venations & markings.
  2. Spreading boards can be bought or made out of Styrofoam or wood to spread wings. The top surface of the board is smooth with a slight upward slant and a central groove. The groove should provide a “snug” fit for the insect’s body & contain a strip of soft material into which insect pins can be placed.
  3. Pin the butterfly or moth as describe in the section on insect pinning.
  4. Cut 2 long, narrow strips of index card to hold down the wings when they are spread.
  5. Place the insect pin into the soft material in the central groove of the spreading board so that the insect’s wings are level with the pinning surface.
  6. Place a straight pin on either side of the insect’s body in the groove so it won’t turn when you start spreading.
  7. Place a strip of the index card over each wing and use 2 straight pins to secure each strip to the board.  Be sure to not pin through the wing!
  8. Never touch your fingers to the upper surface of the wing as scales will be removed.  Always hold or touch this index card strip when spreading the wing.
  9. Use another straight pin to help move the left front wing forward. Place the pin behind the large vein in the forewing up close to the body and gently pull this wing forward until its back edge is at a 90 degree angle with the body.  Still holding your fingers on the cardboard strip, place a second straight pin through the strip (not the wing) up close to the front edge of the wing.
  10. In the same manner move the hind wing forward until a small portion of the hind wing is overlapped by the fore wing.  Use 2 more straights pins to secure the back edge of the cardboard strip.  Again, be sure to not pin through the wings!
  11. Repeat steps 8 – 11 for the right wings of the insect.

Some insects such as the Carolina locust also have unusual markings on  their under wings, so only the right side of these insects should be spread!!!

  1. Allow the wings to dry for several days and then remove the strips, add your labels, and place the insect in your collection.

Writing insect labels:

  1. Each insect will have 2 labels on the pin below the insect’s body.  The top label will be the identification label and the bottom label is the location & collector label.
  2. Obtain labels from your teacher and use black ink only for writing the labels unless placing them in alcohol vials.
  3. The identification label is the top label on the pin below the insect’s body.  It should have the scientific name (genus & species) of the insect on the top line, then the common name of the insect, and the insect’s order on the bottom line.  Remember to capitalize the genus & order and to underline the scientific name!
Musca domestica
Housefly
Diptera

 

  1. The location label goes in the same direction on the bottom of the insect pin.  The location the insect was collected should be written on the top line, then the date the insect was collected, and the name of the collector on the bottom line.  If the collector has a long name, you may write their first initial and their last name.

 

Russellville, Ar.
V – 7 – 14
J. Smith

 

  1. Be sure there is enough room between labels so that both can be read.
  2. Labels should be placed on the pin parallel to the body of a pinned insect or parallel to the point if the insect is card pointed.  Be sure that all labels are readable from the right side when the insect’s head is pointing away from you!!!!

  

Collection Requirements:

Pre-AP Biology  is required to collect 30 insects with a minimum of 12 insect orders

Biology I is required to collect 20 insects with a minimum of 10 insect orders

THE FOLLOWING 8 ORDERS ARE REQUIRED OF ALL BIOLOGY STUDENTS: 

  • Lepidoptera (butterflies & moths)
  • Coleoptera (beetles)
  • Diptera (flies & mosquitoes)
  • Homoptera (cicadas & hoppers)
  • Orthoptera (grasshoppers, crickets,…)
  • Isoptera (termites)
  • Hymenoptera (bees, ants, wasps) 
    • IF YOU ARE ALLERGIC, COLLECT A DIFFERENT ORDER OR AN ANT!
  • Hemiptera (true bugs)

Click here for additional orders

Materials needed to display insects:

  • insect case with lid
  • index cards
  • ribbon, yarn, or string
  • scissors
  • black ink pen
  • straight pins
  • preserved insects (pinned, pointed, & in vials)

Displaying insects:

Remember that your insect collection will not be returned to you, so do not build an expensive case.  Sturdy cases can be made out of 2 cardboard bottoms for cola six packs!

  1. Cases should be no more than 35 by 55 cm in size.  All cases must be sturdy with a lid that can be easily opened for grading.  Remember that the cases will be stacked when you turn them in to me!
  2. If the collection has a clear lid, it must be made of plastic and not glass.
  3. Place a sheet of Styrofoam in the bottom of your case .
  4. Make a label from an unlined index card for the center of your case.  This label should contain your full name, subject, class period, date the collection was turned in to the teacher, number of orders, and number of insects in your collection.  Use straight pins to attach this center card to the Styrofoam. PUT THIS IN THE BOX FIRST!
  5. Cut several small pieces of index card for order labels, and use your black ink pen to write the name of each order  you have in your collection on these.
  6. Arrange insects in the case by order and in rows by descending size (largest to smallest).  Use straight pins to attach the correct order label to the Styrofoam at the top of each row.
  7. Spread out the orders and insects so there are no empty spots in your case.
  8. Cut pieces of yarn or ribbon to separate the orders from each other, and again use straight pins to attach  them to the Styrofoam.
  9. Make sure that all pinned insects are facing the front of your case!
  10. Make sure all identification and collector labels on pins are readable form the right side of the case!!

  

 

Insect

Insects   All Materials © Cmassengale  

Phylum Arthropoda        Subphylum Uniramia          Class Insecta

Characteristics

  • Largest arthropod group
  • Found in freshwater & terrestrial habitats, especially tropical areas
  • Legs, mouthparts, & antenna jointed
  • Body segmented into three sections — head, thorax, & abdomen
  • Six legs & up to two pairs of wings located on thorax
  • Have compound & simple eyes
  • One pair of antennae on head
  • Abdomen has 11 segments
  • Exoskeleton, covering & protecting body, is made of chitin & must be molted to grow
  • Elaborate mouthparts include:
         *  Mandibles – jaws
    *
       Maxillae – paired sensory structures that move food to mouth
      Labium – lower lip
      Labrum – upper lip
      Palpi – used for tasting
  • Known as mandibulates
  • Spiracles on abdomen open into tracheal tubes for oxygen & carbon dioxide exchange
  • Tympanic membranes on 1st abdominal segment aid in hearing
  • Thorax divided into 3 sections — prothorax, mesothorax, & metathorax
  • One pair of legs on each thoracic segment
  • Wings located on mesothorax & metathorax
  • Ovipositor located on the end of the abdomen in female insects & used to dig hole & lay eggs

Common Insect Orders

  • Orthoptera – grasshoppers, crickets, & cockroaches 2 pairs of straight wings & chewing mouthparts)
  • Isoptera – termites (feed on wood)
  • Dermaptera – earwigs (pincers on end of abdomen)
  • Anoplura – sucking lice (wingless parasites)
  • Hemiptera – true bugs (have triangular-shaped scutellum & last 1/3 of wings membranous)
  • Homoptera – aphids & cicadas (membranous wings held roof-like over body
  • Ephemeroptera – mayflies (have 2 cerci on tail, membranous wings, & nonfunctional mouthparts in adults)
  • Odonata – dragonflies & damselflies (2 pairs of equal size, membranous wings, strong fliers, feed on other insects)
  • Neuroptera – Dobson flies &  lacewings (2 pairs of membranous wings)
  • Coleoptera – beetles (hard forewings or elytra, membranous hindwings)
  • Lepidoptera – butterflies & moths (powdery scales covered wings
  • Diptera – flies & mosquitoes (one pair of wings, 2nd pair modified into balancing structure called halteres)
  • Siphonaptera – fleas (parasites on birds & mammals, wingless as adults)
  • Hymenoptera – bees, ants, & wasps (stinger on abdomen for protection, may live together in groups, pollinators)

     Click Here for Pictures of Insect Orders

 

Success of Insects

  • Found everywhere except in deep part of ocean
  • Very short life span & rapidly adapt to new environments
  • Small size helps minimize competition in habitats
  • Flight helps escape predators & move into other environments

Environmental Impact

  • Pollinate almost 2/3’s of all plants
  • Serve as food for fish, birds, & mammals
  • Help recycle materials (termites recycle wood)
  • Make useful byproducts such as silk & honey
  • Some spread disease
  • Agricultural pests

Grasshoppers

External Structure

  • Head with antenna, compound eyes, & chewing mouthparts
  • Walking legs on prothorax & mesothorax; jumping legs on metathorax
  • Tarsus are lower leg segments with spines, hooks, & pads
  • Leathery, protective forewings on mesothorax & membranous hindwings for flight on metathorax
  • Covering over thorax called pronotum

Internal Structure
Digestive & Excretory Systems

  • Cutting & chewing mouthparts (labium, labrum, mandibles, & maxillae)
  • Saliva added to food in mouth
  • Esophagus carries food to crop for temporary storage
  • Gizzard has chitinous plates to grind food
  • Midgut (insect’s stomach) has gastric caeca (pouches) to secrete digestive enzymes to break down food
  • Food is absorbed into the body cavity or coelom in the hindgut (composed of the colon & rectum)
  • Malpighian tubules filter chemical wastes from the blood & deposit them in the rectum where they leave through the anus

Circulatory System

  • Open circulation of blood
  • Aorta is the largest blood vessel carrying blood to the body cells
  • Hearts are muscular regions of the aorta in the posterior end of the abdomen that pump blood toward head
  • Blood flows back toward abdomen carrying digested food & re-enters the aorta through openings called ostia

Respiratory System

  • Air enters through openings called spiracles along the sides of the abdomen & enters into tracheal tubes that branch into smaller tracheoles where gas exchange with body cells occurs 
  • Tracheal tubes carry oxygen to body cells & return carbon dioxide to leave the body though spiracles

Nervous System

  • Simple brain, nerve cords, & ganglia 
  • Three simple eyes or ocelli (detect light) & a pair of compound eyes (can detect movement but not images)
  • Tympanic membrane on 1st abdominal segment
  • Pair of antenna contains sense organs for touch, taste, & smell detects sound
  • Sensory hairs found on parts of the body
  • Palpi for taste

Reproductive System

  • Reproductive organs (ovaries & testes) located  in abdomen
  • Male deposits sperm into female’s seminal receptacle
  • Stored sperm fertilizes eggs as they  are released by female
  • Ovipositor on tip of female’s abdomen is used to lay eggs
  • Separate sexes
  • Lay large number of eggs to ensure survival

Development

  • Most insects go through changes in form & size called metamorphosis
  • Some insects such as silverfish don’t go through metamorphosis
  • Incomplete metamorphosis goes from egg to nymph (immature form that looks like adult but without fully developed wings) to adult (3 stages)
  • Instars are growth periods between molts of nymphs & larva
  • Grasshoppers, termites, & true bugs go through incomplete metamorphosis


HEMIPTERAN (TRUE BUG) NYMPH

  • Complete metamorphosis goes from egg to larva (segmented & wormlike) to pupa  to adult (4 stages)


BUTTERFLY LARVA (CATERPILLAR)

  • Butterflies, beetles, & flies go through complete metamorphosis
  • In pupal stage, larval tissues break down & cells called imaginal disk develops into tissues of the adult
  • Cocoon or chrysalis is a protective case formed around the pupa


BUTTERFLY COCOON

  • Metamorphosis controlled by hormones
    * Brain hormone stimulates the release of molting hormone (ecdysone)
    * When juvenile hormone level high, larva molts
    * When juvenile hormone level low, larva pupates
    * When juvenile hormone absent, adult emerges from pupal case
  • Different stages of metamorphosis eliminates competition between larva & adults for food & space
  • Multi-stage life cycle helps insects withstand harsh weather
  • Different stages have different functions (caterpillar/growth & adult/reproduction)

Defense Mechanisms

  • Bombardier beetle sprays noxious chemical


BOMBARDIER BEETLE

  • Wasps & bees can sting
  • Some insects use camouflage to blend into their environments
  • Some insects taste bad & have warning colorations 


PAPER WASP

  • Mullerian mimicry – poisonous or dangerous species have similar patterns of warning coloration so predators avoid all the species (black & yellow stripes on bees & wasps)
  • Batesian mimicry – species that are nonpoisonous or not bad tasting have colorations that mimic other poisonous or bad tasting species (Viceroy butterfly mimics bad tasting Monarch)

Insect Communication

  • Insects may communicate with each other using sound (cricket chirps), light (firefly), or “dances” (honeybee)
  • Pheromones are chemicals released by some insects to attract mates or mark trails

Insect Behavior

  • Insects may be solitary or social
  • Social insects (bees, ants, & some wasps) live together in groups & share work (division of labor)
  • Social insects have a caste system with different individuals doing different jobs
  • Honeybee caste system:
    * Workers
    – sterile females
    – care for queen & feed her honey and pollen
    – make beeswax for hive
    – fan wings to cool hive
    – eat honey
    – collect nectar, pollen, & royal jelly
    – live about 6 weeks
    – nurse bees care for larva
    – secrete royal jelly to feed new queen
    * Drones
    – males
    – mate with queen
    – feed by workers
    – driven out of hive to conserve food during winter
    * Queen
    – reproductive female
    – mate only once but store sperm for up to 5 years in seminal receptacles
    – feed by workers
    – secretes chemical called queen factor that prevents other females from sexually maturing
    – leaves hive with 1/2 the workers if there is overcrowding


HONEYBEE HIVE

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