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Biology - Chapter 28 “Arthropods”. Charles Page High School Stephen L. Cotton. Section 28-1 Introduction to Arthropods. OBJECTIVES: Describe the four subphyla of arthropods. Section 28-1 Introduction to Arthropods. OBJECTIVES: Explain how arthropods perform their essential life functions.

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biology chapter 28 arthropods

Biology - Chapter 28“Arthropods”

Charles Page High School

Stephen L. Cotton

section 28 1 introduction to arthropods
Section 28-1Introduction to Arthropods
  • OBJECTIVES:
    • Describe the four subphyla of arthropods.
section 28 1 introduction to arthropods3
Section 28-1Introduction to Arthropods
  • OBJECTIVES:
    • Explain how arthropods perform their essential life functions.
section 28 1 introduction to arthropods4
Section 28-1Introduction to Arthropods
  • OBJECTIVES:
    • Discuss metamorphosis in arthropods.
section 28 1 introduction to arthropods5
Section 28-1Introduction to Arthropods
  • Phylum Arthropoda - vary enormously in size, shape, and habits
  • More than a million arthropod species have been described, and scientists are certain many more have not yet been found (such as in the tropics)
section 28 1 introduction to arthropods6
Section 28-1Introduction to Arthropods
  • Phylum Arthropoda is subdivided into four subphyla:
    • 1. Subphylum Trilobita
    • trilobites are thought to be the oldest subphylum
    • these were dwellers in ancient seas; they are now all extinct
section 28 1 introduction to arthropods7
Section 28-1Introduction to Arthropods
  • Phylum Arthropods is subdivided into four subphyla:
    • 2. Subphylum Chelicerata
    • chelicerates include spiders, ticks, mites, scorpions, and horseshoe crabs
section 28 1 introduction to arthropods8
Section 28-1Introduction to Arthropods
  • Phylum Arthropods is subdivided into four subphyla:
    • 3. Subphylum Crustacea
    • crustaceans include such familiar (and edible) organisms as crabs, shrimp, crayfish
section 28 1 introduction to arthropods9
Section 28-1Introduction to Arthropods
  • Phylum Arthropods is subdivided into four subphyla:
    • 4. Subphylum Uniramia
    • includes most arthropods: centipedes, millipedes, and all insects (bees, moths, flies, grasshoppers, beetles)
section 28 1 introduction to arthropods10
Section 28-1Introduction to Arthropods
  • Why are there so many?
    • Been evolving on Earth for a long time; the first appeared in the sea more than 600 million years ago
    • colonized all parts of the sea and most freshwater habitats, as well as the land
section 28 1 introduction to arthropods11
Section 28-1Introduction to Arthropods
  • The ancestors of the arthropods were soft-bodied animals that left few fossils
    • early forms are thought to be similar to that of the trilobites
    • a thick, tough outer covering, and composed of many segments with appendages
section 28 1 introduction to arthropods12
Section 28-1Introduction to Arthropods
  • The appendages were branched into one walking leg and one gill
    • Figure 28-3, page 608
  • Most today exhibit two trends away from trilobites:
    • 1. Fewer body segments
    • 2. Appendages more specialized
section 28 1 introduction to arthropods13
Section 28-1Introduction to Arthropods
  • Although there are many different types of arthropods, they all have three important arthropod features:
    • 1. Tough exoskeleton
    • 2. Series of jointed appendages
    • 3. Segmented body
section 28 1 introduction to arthropods14
Section 28-1Introduction to Arthropods
  • Also have:
    • brain, located in dorsal part of head
    • ventral nerve cord
    • open circulatory system, powered by a single heart
section 28 1 introduction to arthropods15
Section 28-1Introduction to Arthropods
  • The exoskeleton is made of chitin (a protein)
    • some are leathery and flexible
    • others are extremely hard
  • exoskeleton provides protection from physical damage and also support; many are waterproof
section 28 1 introduction to arthropods16
Section 28-1Introduction to Arthropods
  • Although the exoskeleton acts like a “suit of armor”, it has some disadvantages
    • cannot grow as the animal grows
    • movement only at the joints
    • very heavy if the animal was to grow large
section 28 1 introduction to arthropods17
Section 28-1Introduction to Arthropods
  • All arthropods have jointed appendages (arthro- means joint; -pod means foot) that enable them to move
  • remaining appendages evolved into adaptations for different environments: antennae; claws; walking legs; wings; flippers
section 28 1 introduction to arthropods18
Section 28-1Introduction to Arthropods
  • All arthropods have segmented bodies
    • some have worm-like bodies, such as centipedes and millipedes
    • others have lost some of the body segments, or have fused them together, such as insects
section 28 1 introduction to arthropods19
Section 28-1Introduction to Arthropods
  • 1. Feeding- almost any type of food we can imagine
    • herbivores; carnivores; parasites; filter feeders; detritus feeders (Figure 28-6, p.610)
    • some herbivores are selective, and others will eat just about anything green
section 28 1 introduction to arthropods20
Section 28-1Introduction to Arthropods
  • 2. Respiration- 3 basic types of respiratory structures:
    • a) gills; b) book gills and book lungs; and c) tracheal tubes
  • many aquatic varieties, such as crabs and shrimp, have gills that look like a row of feathers under cover of their exoskeleton
section 28 1 introduction to arthropods21
Section 28-1Introduction to Arthropods
  • The gills are formed from the same structures as the mouthparts and legs
    • movement of the mouthparts and legs keeps a steady stream of water moving over the gills
section 28 1 introduction to arthropods22
Section 28-1Introduction to Arthropods
  • Book gills (found in the horseshoe crabs) and book lungs (found in spiders and relatives) are unique to these arthropods
    • several sheets of tissue are layered like pages of a book; this increases the surface area for gas exchange
section 28 1 introduction to arthropods23
Section 28-1Introduction to Arthropods
  • An opening called the spiracle connects the sac containing the book lungs with the fresh air outside
  • Most terrestrial arthropods (insects for example) have another unique structure- long branching tracheal tubes
section 28 1 introduction to arthropods24
Section 28-1Introduction to Arthropods
  • From spiracles, long branching tracheal tubes reach deep into the animal’s tissues
    • supplies oxygen by diffusion
    • as they move, body muscles cause the tracheae to shrink and expand; thus filling with air; works well in small animals
section 28 1 introduction to arthropods25
Section 28-1Introduction to Arthropods
  • 3. Internal transport- a well developed heart pumps blood through an open circulatory system
    • blood leaves the vessels, and moves through spaces in the tissue called sinuses
section 28 1 introduction to arthropods26
Section 28-1Introduction to Arthropods
  • 4. Excretion- solid waste leaves through the anus
    • nitrogen-containing wastes from cellular metabolism are removed in a variety of ways
    • a) insects and spiders have Malpighian tubules that filter the blood
section 28 1 introduction to arthropods27
Section 28-1Introduction to Arthropods
  • b) aquatic arthropods have wastes diffuse into the surrounding water at unarmored places, such as gills
  • c) some, such as lobster, have a green gland located near the base of the antennae; emptied through openings on head
section 28 1 introduction to arthropods28
Section 28-1Introduction to Arthropods
  • 5. Response- many have well developed nervous systems
    • all have a brain, consisting of a pair of ganglia in the head; this is the central switchboard for incoming information and outgoing instructions
section 28 1 introduction to arthropods29
Section 28-1Introduction to Arthropods
  • Nerve cord runs on ventral side of the body; along this nerve cord are additional ganglia that serve as local command centers
    • these coordinate legs and wings; this is why they might still move even though the head has been cut off!
section 28 1 introduction to arthropods30
Section 28-1Introduction to Arthropods
  • Simple sense organs such as statocysts and chemical receptors
    • also have compound eyes; more than 2000 separate lenses; can detect color and movement very well
    • may see ultraviolet light
section 28 1 introduction to arthropods31
Section 28-1Introduction to Arthropods
  • May have well-developed sense of taste, although the receptors are located in strange places
    • not only on the mouthparts, but also on antennae and legs
section 28 1 introduction to arthropods32
Section 28-1Introduction to Arthropods
  • Many insects have well-developed ears that hear sounds above the human range, but the ears are in odd places
    • eardrums in grasshoppers, for example, are behind their legs
    • spiders are sensitive to vibrations in their webs
section 28 1 introduction to arthropods33
Section 28-1Introduction to Arthropods
  • The arthropods well-developed sense organs allow it to detect and escape predators
    • this is in combination with their protective exoskeleton
    • but, there are also additional methods of protection
section 28 1 introduction to arthropods34
Section 28-1Introduction to Arthropods
  • Venomous stings- bees, ants
  • powerful claws- lobsters, crabs
  • nasty chemicals- millipedes
  • creating a diversion- drop claw
  • visual trickery- matching color and texture of surroundings
  • imitate other dangerous species- called mimicry (p.614)
section 28 1 introduction to arthropods35
Section 28-1Introduction to Arthropods
  • 6. Movement- well-developed muscle systems coordinated by nervous system (Figure 28-13, p.614)
    • the pull of muscles on the exoskeleton allows them to beat wings to fly; push legs to walk or jump; or beat flippers against water to swim
section 28 1 introduction to arthropods36
Section 28-1Introduction to Arthropods
  • 7. Reproduction- usually very simple
    • male produces sperm; female produces egg
    • fertilization usually takes place inside the body of the female
  • ** Stop Day #1
section 28 1 introduction to arthropods37
Section 28-1Introduction to Arthropods
  • Growth and Development- the exoskeleton (as useful as they are), present a problem in growth
    • it does not grow as the animal does; thus must be replaced
    • arthropods will molt, or shed their exoskeleton; controlled by several hormones
section 28 1 introduction to arthropods38
Section 28-1Introduction to Arthropods
  • Steps in molting:
    • 1. Produce molting hormone
    • 2. Digest inner parts of exoskeleton to recycle chemicals
    • 3. Form new exoskeleton; shed old exoskeleton
    • 4. Harden new exoskeleton
section 28 1 introduction to arthropods39
Section 28-1Introduction to Arthropods
  • The animal must wait for the new exoskeleton to harden; may only be a few hours or a few days
    • quite vulnerable during this time; thus they might need to hide from predators
section 28 1 introduction to arthropods40
Section 28-1Introduction to Arthropods
  • This molting may take place several times
    • in most cases, it will involve metamorphosis- a change in form
    • there are two forms of metamorphosis
section 28 1 introduction to arthropods41
Section 28-1Introduction to Arthropods
  • Metamorphosis:
    • 1. Incomplete metamorphosis hatches eggs into young animals that look like small adults; lack functioning sexual organs and wings
    • Figure 28-15, page 615 for the grasshopper on the left
section 28 1 introduction to arthropods42
Section 28-1Introduction to Arthropods
  • Metamorphosis:
    • 2. Complete metamorphosis involves four stages:
    • a) the egg
    • b) larvae (a wormlike stage that does not look like the adults)
    • c) pupa (an inactive stage that totally rearranges the body)
    • d) the adult
section 28 1 introduction to arthropods43
Section 28-1Introduction to Arthropods
  • Hormone interaction:
    • high levels of juvenile hormone keep an insect in the larval form; when it drops below a certain point- it becomes pupa
    • molting hormone controls the molting process
section 28 1 introduction to arthropods44
Section 28-1Introduction to Arthropods
  • Because of the balance of juvenile hormone, molting hormone, and others- it is possible to combat insects by tampering with their hormone levels
    • can prevent molting; thus no adults, and no reproduction!
section 28 2 spiders and their relatives
Section 28-2Spiders and their Relatives
  • OBJECTIVES:
    • Discuss the distinguishing characteristics of chelicerates.
section 28 2 spiders and their relatives46
Section 28-2Spiders and their Relatives
  • OBJECTIVES:
    • Describe and give examples of members of the two main groups of animals in the subphylum Chelicerata.
section 28 2 spiders and their relatives47
Section 28-2Spiders and their Relatives
  • OBJECTIVES:
    • Explain how arachnids obtain food.
section 28 2 spiders and their relatives48
Section 28-2Spiders and their Relatives
  • Subphylum Chelicerata- called chelicerates, includes spiders and their relatives- horseshoe crabs, ticks, and scorpions
    • characterized by a two-part body and mouthparts called “chelicerae”
section 28 2 spiders and their relatives49
Section 28-2Spiders and their Relatives
    • also lack sensory “feelers” found on the heads of most other arthropods
  • the two-part body is:
    • 1. Cephalothorax
    • 2. Abdomen
section 28 2 spiders and their relatives50
Section 28-2Spiders and their Relatives
  • Cephalothorax- contains the brain, eyes, mouth and mouthparts, and esophagus
    • posterior end is the first part of the digestive system, and several pairs of walking legs
  • Abdomen- contains most of the internal organs (Fig. 28-17, p.617)
section 28 2 spiders and their relatives51
Section 28-2Spiders and their Relatives
  • All chelicerates have two pairs of appendages attached near the mouth that are adapted as mouthparts
    • first pair are chelicerae
    • second pair is longer, and called pedipalps
  • both serve different feeding job
section 28 2 spiders and their relatives52
Section 28-2Spiders and their Relatives
  • Among the oldest chelicerates are the horseshoe crabs
    • somewhat misleading name, because they are not true crabs
    • have not changed much in the last 430 million years
    • heavily armor plated (p.618)
section 28 2 spiders and their relatives53
Section 28-2Spiders and their Relatives
  • Have 5 pairs of walking legs
  • long spike-like tails
  • can grow up to 60 cm long, about the size and shape of a frying pan
  • newly hatched are called trilobite larvae because they look so much like them
section 28 2 spiders and their relatives54
Section 28-2Spiders and their Relatives
  • Class Arachnida- includes spiders, ticks, scorpions, and mites
    • have 4 pairs of walking legs
    • pedipalps capture and hold prey; chelicerae adapted for biting and sucking out soft parts
section 28 2 spiders and their relatives55
Section 28-2Spiders and their Relatives
  • Spiders- predators that usually feed on insects
  • capture prey in a variety of ways:
    • ensnare in a web
    • stalk, and then pounce
    • ambush under camouflage, then leap out and grab
section 28 2 spiders and their relatives56
Section 28-2Spiders and their Relatives
  • Once captured:
    • 1. Hollow fanglike chelicerae inject paralyzing venom
    • 2. Mouth introduces enzymes
    • 3. Enzymes break down tissue
    • 4. Spider sucks up the liquefied tissues with esophagus and specialized pumping stomach
section 28 2 spiders and their relatives57
Section 28-2Spiders and their Relatives
  • Whether or not they spin webs, all spiders produce a strong, flexible protein called silk
    • produced in special glands in the abdomen
    • is 5 times stronger than steel
    • makes webs, cocoons for eggs, or wrappings for prey
section 28 2 spiders and their relatives58
Section 28-2Spiders and their Relatives
  • Forces the liquid silk through organs called spinnerets
    • it then hardens into a single strand
    • do not have to learn “how” to spin the intricate webs; it is programmed into their brain as soon as they hatch
section 28 2 spiders and their relatives59
Section 28-2Spiders and their Relatives
  • Mites and Ticks- small arachnids, many of which are parasites
    • the chelicerae are needlelike structures that are used to pierce the skin of their hosts
    • the chelicerae also have large teeth to help the parasite hold on to the host
section 28 2 spiders and their relatives60
Section 28-2Spiders and their Relatives
  • Some, such as spider mites,are major agricultural pests
  • others, such as chiggers, mange and scabies mites,cause painful itching rashes in humans
  • tick bites are not just annoying; they may also spread Rocky Mountain spotted fever and Lyme disease
section 28 2 spiders and their relatives61
Section 28-2Spiders and their Relatives
  • Scorpions- carnivores that prey on other invertebrates, usually insects
    • pedipalps are enormously enlarged into a pair of claws
    • abdomen is long and segmented; ends in a venomous barb to sting prey
section 28 2 spiders and their relatives62
Section 28-2Spiders and their Relatives
  • Scorpion grabs the prey with it’s pedipalps; then whips the abdomen over it’s head to sting the prey- thus killing or paralyzing it
  • they like to crawl in moist, dark places- good idea to check your shoes when putting them on!
section 28 3 crustaceans
Section 28-3Crustaceans
  • OBJECTIVES:
    • Discuss the distinguishing characteristics of crustaceans.
section 28 3 crustaceans64
Section 28-3Crustaceans
  • OBJECTIVES:
    • Describe the anatomy of a typical crustacean.
section 28 3 crustaceans65
Section 28-3Crustaceans
  • Subphylum Crustacea- over 35,000 species, mainly aquatic
  • tiny as a water flea (0.25 mm) to Japanese spider crabs (6 meter)
  • characterized by: a hard exoskeleton; 2 pairs of antennae; mouthparts called mandibles
section 28 3 crustaceans66
Section 28-3Crustaceans
  • Main body parts are the head, thorax, and abdomen
  • in many, the head and thorax have fused = cephalothorax, covered by a tough shell called the carapace
  • many (crabs, lobsters) have calcium carbonate that makes their exoskeleton very hard
section 28 3 crustaceans67
Section 28-3Crustaceans
  • In crustaceans, the first two pairs of appendages are “feelers” called antennae, which bear many sensory hairs
  • third pair of appendages are mouthparts called mandibles
    • might bite and grind; filter feeding; pick up detritus
section 28 3 crustaceans68
Section 28-3Crustaceans
  • Appendages can vary greatly
    • barnacles have delicate, feathery appendages for filter feeding
    • others have legs for walking or swimming
    • some modified for fertilization, carrying eggs, spearing prey
section 28 3 crustaceans69
Section 28-3Crustaceans
  • Appendages are adapted for:
    • the large claws catch prey; pick up, crush, and cut food- these are on the thorax
    • 4 pairs of walking legs, also on the thorax
    • Flipper-like swimmerets for swimming on the abdomen
section 28 3 crustaceans70
Section 28-3Crustaceans
  • The paddle-like appendages and the final abdominal segment form a large, flat tail
    • very powerful; a crayfish can snap forward, thus rapidly pulling the animal backwards
  • “roly-poly” in Figure 28-22, page 620- pill bug (a crustacean)
section 28 4 insects and their relatives
Section 28-4Insects and their Relatives
  • OBJECTIVES:
    • Describe and give examples of three classes in the subphylum Uniramia.
section 28 4 insects and their relatives72
Section 28-4Insects and their Relatives
  • OBJECTIVES:
    • Discuss the anatomy of a typical insect.
section 28 4 insects and their relatives73
Section 28-4Insects and their Relatives
  • OBJECTIVES:
    • Explain how insects communicate.
section 28 4 insects and their relatives74
Section 28-4Insects and their Relatives
  • Subphylum Uniramia- more species than all other groups of animals alive today!
    • includes insects, centipedes, and millipedes
    • characterized by one pair of antennae; appendages that do not branch (Uni- means one; ramus means branch)
section 28 4 insects and their relatives75
Section 28-4Insects and their Relatives
  • These arthropods, which display a multitude of forms and habits, are thought to have evolved on land about 400 million years ago, during the Devonian Period
    • long before dinosaurs!
    • they inhabit almost every terrestrial habitat on Earth
section 28 4 insects and their relatives76
Section 28-4Insects and their Relatives
  • Centipedes and Millipedes- these are the “many-legged” animals
    • characterized by a long, wormlike body composed of many leg-bearing segments
    • Figure 28-25, page 622
section 28 4 insects and their relatives77
Section 28-4Insects and their Relatives
  • They lack closable spiracles and a waterproof coating on their exoskeleton
    • thus they lose water easily
    • therefore, they tend to live beneath rocks, in soil, or in other relatively moist areas
section 28 4 insects and their relatives78
Section 28-4Insects and their Relatives
  • Class Chilopoda- centipedes
  • these are carnivores that have in addition to their mouthparts, a pair of poison claws in their head region
    • used to catch and stun or kill prey- other arthropods, earthworms, toads, small snakes, and even mice
section 28 4 insects and their relatives79
Section 28-4Insects and their Relatives
  • Most centipedes in North America are 3-6 cm long; but some tropical species are brightly colored, and up to 26 cm
  • Despite the name (which means 100 legs), they can have a variable number, depending upon how long they are
section 28 4 insects and their relatives80
Section 28-4Insects and their Relatives
  • There is only one pair of legs per body segment
    • except the mouth, which has the poison claws, and the last three segments (which are legless)
section 28 4 insects and their relatives81
Section 28-4Insects and their Relatives
  • Class Diplopoda- these are the millipedes, and they do not have a thousand legs like the name implies
    • they have 2 pairs of legs per body segment
    • these are timid creatures, and are detritus feeders
section 28 4 insects and their relatives82
Section 28-4Insects and their Relatives
  • Class Insecta- the insects have more than 900,000 species; new ones are being discovered in the tropics all the time
    • 3 out of every 4 animals!
    • three part body: head, thorax, and abdomen. There are 3 pairs of legs on the thorax
section 28 4 insects and their relatives83
Section 28-4Insects and their Relatives
  • A typical insect has one pair of antennae, one pair of compound eyes on the head, two pairs of wings on the thorax, and uses a system of tracheal tubes for respiration
  • Figure 28-26, page 623
section 28 4 insects and their relatives84
Section 28-4Insects and their Relatives
  • Insects get their name from the Latin word insectum, meaning notched- refers to the division of their body into the three parts
    • many insects, such as ants, have clear cut divisions- others such as grasshopper may not have body parts sharply defined
section 28 4 insects and their relatives85
Section 28-4Insects and their Relatives
  • Feeding- insects have 3 pairs of appendages that are used as mouthparts, including a pair of mandibles (jaws)
  • many shapes and varieties:
    • grasshopper: cut / chew plants
    • mosquito: tube pierces skin to suck blood (females only)
section 28 4 insects and their relatives86
Section 28-4Insects and their Relatives
  • butterfly: long tube for sipping nectar
  • bee: chewing and gathering nectar
  • fly: spongy mouthpart used to soak up food
section 28 4 insects and their relatives87
Section 28-4Insects and their Relatives
  • The saliva of female mosquitoes, which is injected when the mosquito “bites”, contains chemicals that prevent blood from clotting- also has chemicals that cause the itching
  • bee body covered with many hairs that collect pollen
section 28 4 insects and their relatives88
Section 28-4Insects and their Relatives
  • Chemicals in bee saliva help change nectar into a more digestible form- honey
    • glands on the bee abdomen secrete wax, which is used to build storage chambers for food and others structures within a beehive
section 28 4 insects and their relatives89
Section 28-4Insects and their Relatives
  • Movement- insects have 3 pairs of walking legs
    • often equipped with spines or hooks for holding on, or used for defense
    • may be used for jumping (fleas), or holding prey (praying mantis)
section 28 4 insects and their relatives90
Section 28-4Insects and their Relatives
  • Movement- along with birds and bats, insects are the only living organisms capable of unassisted flight
    • flight ability varies greatly; from slow butterflies to fast flies, bees, and dragonflies
    • requires enormous energy, thus have oversized mitochondria
section 28 4 insects and their relatives91
Section 28-4Insects and their Relatives
  • Insect societies- many animals form colonies, collections of individuals of the same species
    • several types of insects for a special colony called a society
    • separate individuals are dependent upon one another for survival
section 28 4 insects and their relatives92
Section 28-4Insects and their Relatives
  • Insect societies- examples are termites, wasps, bees, and ants
    • all called social insects
    • they have a division of labor:
    • 1) reproductive females
    • 2) reproductive males
    • 3) workers
section 28 4 insects and their relatives93
Section 28-4Insects and their Relatives
  • Reproductive females = queen, typically there is only one, and usually the largest individual in the colony- page 625
    • termite queen may be 14 cm long, 10 times normal
    • can produce more than 30,000 eggs a day!
section 28 4 insects and their relatives94
Section 28-4Insects and their Relatives
  • The reproductive males function only to fertilize the queen’s eggs
    • queen bee mates only once
    • the successful males die after mating, and the unsuccessful males are ejected from the colony and soon perish (since they are no longer needed!)
section 28 4 insects and their relatives95
Section 28-4Insects and their Relatives
  • The workers perform all colony tasks except reproduction:
    • care for queen and eggs; gather and store food; build and maintain the colony’s home
    • in bees, the workers are sterile females; in termites, the workers consist of males and females
section 28 4 insects and their relatives96
Section 28-4Insects and their Relatives
  • Insect communication- may use sounds, visual, chemical, or other methods
    • may be necessary to find mate
    • male crickets chirp by rubbing their forewings together
    • male cicadas buzz special membranes on their abdomen
section 28 4 insects and their relatives97
Section 28-4Insects and their Relatives
    • Male fireflies turn a light producing organ in their abdomen on and off
  • many insects can release chemicals that attract the opposite sex- called pheromones
  • communication in non-social insects not near as complex
section 28 4 insects and their relatives98
Section 28-4Insects and their Relatives
  • Queen bee produces a pheromone, called queen substance, that prevents the development of rival queens
    • this substance makes the worker bees unable to lay eggs
    • need a new queen? Feed the larvae a special diet
section 28 4 insects and their relatives99
Section 28-4Insects and their Relatives
  • Honeybees communicate with sound and movement, as well as with pheromones
    • worker bees are able to convey information about the type, quality, direction, and distance of food by “dancing”
  • Austrian biologist Karl von Frisch
section 28 4 insects and their relatives100
Section 28-4Insects and their Relatives
  • 1. Round dance- bee that has found food will circle first one way, then the other, over and over again (Fig. 28-32, p.627)
    • tells others that food is within 50 meters, but not direction
    • frequency of dance conveys quality of the food
section 28 4 insects and their relatives101
Section 28-4Insects and their Relatives
  • 2. Waggle dance- the bee that has found food runs forward in a straight line while wiggling her abdomen, then circles around much like a figure eight
    • food is more then 50 m away
    • the direction of the dance tells the direction of the food source
section 28 5 how arthropods fit into the world
Section 28-5 How Arthropods Fit Into the World
  • OBJECTIVES:
    • Describe how arthropods interact with other organisms in nature.
section 28 5 how arthropods fit into the world103
Section 28-5 How Arthropods Fit Into the World
  • OBJECTIVES:
    • Discuss how arthropods affect humans.
section 28 5 how arthropods fit into the world104
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  • Such a large diverse group will play many roles in the natural world
    • can be a direct source of food for many organisms
    • either eating others or being eaten by them
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  • Involved in symbiotic relationships Fig. 28-34, p.629
  • pores of our skin are home to thousands of harmless microscopic mites; no matter how much we clean our home, even our beds, there are millions of these dust mites
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  • Agriculture would be impossible if not for bees, butterflies, wasps, moths, and flies that pollinate
  • honey from bees; silk from silkworm moths
  • shrimp, crab, crayfish, lobster used as a food source for humans
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  • Grasshoppers and termites can also be eaten; they can also do considerable damage to crops and wood materials
  • many insects and spiders are predators on other harmful species
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  • Chemicals from arthropods
    • extract of horseshoe crab blood is used to test purity of medications
    • chitin from exoskeletons used to dress wounds and make thread for surgical stitches
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  • The chitin may also be sprayed on fruit and frozen food to prevent spoilage
  • the adhesive that barnacles use to attach themselves to rocks under water could be used in dentistry or underwater construction
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  • Spider venom is being tested as a pesticide
  • spider silk that could be used in making aircraft, helmets, bulletproof vests, and surgical thread
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  • However good they are, they can also do considerable damage:
    • parasites damage livestock and crops
    • mosquitoes annoying bites and the spread of malaria and yellow fever
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  • Biting flies carry diseases such as sleeping sickness and river blindness
  • fleas carrying bubonic plague
  • termites damaging wood
  • locusts (grasshoppers) destroying crops