2. Biology - Chapter 28 “Arthropods”

3. Introduction to Arthropods
Phylum Arthropoda - vary enormously in size, shape, and habits

4. Crustaceans 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

5. Introduction to Arthropods
Although there are many different types of arthropods, they all have four important arthropod features:
Tough exoskeleton – shed to allow for growth (molt)
Protection
Prevent water loss
Made up of chitin (protein)
2. Series of jointed appendages in pairs
3. Segmented body – head, thorax, abdomen

6. Introduction to Arthropods
Well developed nervous system
-- sense organs – eyes, touch, hearing
brain, located in dorsal part of head
open circulatory system, powered by a single heart
Flows into open cavities called sinuses

7. Introduction to Arthropods
Development through Metamorphosis:
1. Incomplete metamorphosis eggs hatch to nymph (kid) to adult
examples: grasshoppers and crickets

8. Spiders and their Relatives
also lack sensory “feelers” found on the heads of most other arthropods
the two-part body is:
1. Cephalothorax
2. Abdomen

9. Introduction to Arthropods
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
Moths, butterflies, flies, lady bugs

10. Introduction to Arthropods
Phylum Arthropods is subdivided into three subphyla:
1. Subphylum Chelicerata
Includes spiders, ticks, mites, scorpions, and horseshoe crabs

11. Spiders and their Relatives
Cephalothorax- contains the brain, eyes, mouth and mouthparts, and esophagus
Abdomen- contains most of the internal organs

12. Spiders 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

13. Spiders and their Relatives
Among the oldest chelicerates are the horseshoe crabs

14. Spiders 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

15. Introduction to Arthropods 3 Subphylums
1. Subphylum Crustacea
includes crabs, shrimp, crayfish

16. Crustaceans Main body parts are the head, thorax, and abdomen
in many, the head and thorax have fused = cephalothorax, many (crabs, lobsters)

18. Introduction to Arthropods
3. Subphylum Uniramia includes most arthropods: centipedes, millipedes, and all insects (bees, moths, flies, grasshoppers, beetles)

19. Insects Anatomy Head Antennae (sensory appendages) Mouthparts
Compound eye
Thorax
3 pairs of legs
Wings?
Abdomen

20. Insects and their Relatives
Subphylum Uniramia- more species than all other groups of animals alive today!
1. Class Insecta – flies, bees, butterflies, dragonflies, grasshoppers, lice, mosquitos
2. Class Chilopoda – centipedes
3. Class Diploda -- millipedes

22. Section 28-2 Spiders and their Relatives
Have 4 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

23. Section 28-2 Spiders 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

24. Section 28-2 Spiders 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

25. Section 28-2 Spiders 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

26. Section 28-2 Spiders 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

27. Section 28-2 Spiders 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

28. Section 28-2 Spiders 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

29. Section 28-2 Spiders 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

30. Section 28-2 Spiders 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!

31. Discuss the distinguishing characteristics of crustaceans.
Section 28-3 Crustaceans
OBJECTIVES:
Discuss the distinguishing characteristics of crustaceans.

32. Describe the anatomy of a typical crustacean.
Section 28-3 Crustaceans
OBJECTIVES:
Describe the anatomy of a typical crustacean.

33. Section 28-3 Crustaceans
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

34. Section 28-3 Crustaceans 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

35. Section 28-3 Crustaceans 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

36. Section 28-3 Crustaceans
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)

37. Section 28-4 Insects and their Relatives
OBJECTIVES:
Describe and give examples of three classes in the subphylum Uniramia.

38. Section 28-4 Insects and their Relatives
OBJECTIVES:
Discuss the anatomy of a typical insect.

39. Section 28-4 Insects and their Relatives
OBJECTIVES:
Explain how insects communicate.

40. Section 28-4 Insects 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

41. Section 28-4 Insects 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

42. Section 28-4 Insects 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

43. Section 28-4 Insects 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)

44. Section 28-4 Insects 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

45. Section 28-4 Insects 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

46. Section 28-4 Insects 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

47. Section 28-4 Insects 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

48. Section 28-4 Insects 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)

49. Section 28-4 Insects and their Relatives
butterfly: long tube for sipping nectar
bee: chewing and gathering nectar
fly: spongy mouthpart used to soak up food

50. Section 28-4 Insects 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

51. Section 28-4 Insects 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

52. Section 28-4 Insects 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)

53. Section 28-4 Insects 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

54. Section 28-4 Insects 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

55. Section 28-4 Insects 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

56. Section 28-4 Insects 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!

57. Section 28-4 Insects 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!)

58. Section 28-4 Insects 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

59. Section 28-4 Insects 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

60. Section 28-4 Insects 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

61. Section 28-4 Insects 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

62. Section 28-4 Insects 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

63. Section 28-4 Insects and their Relatives
1. Round dance- bee that has found food will circle first one way, then the other, over and over again (Fig , p.627)
tells others that food is within 50 meters, but not direction
frequency of dance conveys quality of the food

64. Section 28-4 Insects 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

65. Section 28-5 How Arthropods Fit Into the World
OBJECTIVES:
Describe how arthropods interact with other organisms in nature.

66. Section 28-5 How Arthropods Fit Into the World
OBJECTIVES:
Discuss how arthropods affect humans.

67. Section 28-5 How Arthropods Fit Into the World
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

68. Section 28-5 How Arthropods Fit Into the World
Involved in symbiotic relationships Fig , 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

69. Section 28-5 How Arthropods Fit Into the World
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

70. Section 28-5 How Arthropods Fit Into the World
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

71. Section 28-5 How Arthropods Fit Into the World
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

72. Section 28-5 How Arthropods Fit Into the World
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

73. Section 28-5 How Arthropods Fit Into the World
Spider venom is being tested as a pesticide
spider silk that could be used in making aircraft, helmets, bulletproof vests, and surgical thread

74. Section 28-5 How Arthropods Fit Into the World
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

75. Section 28-5 How Arthropods Fit Into the World
Biting flies carry diseases such as sleeping sickness and river blindness
fleas carrying bubonic plague
termites damaging wood
locusts (grasshoppers) destroying crops