1. Chapter 26 Arthropods Joint limbed arthropods (1 min)

4. Arthropod Characteristics
Segmented
Coelomates
Invertebrate
Bilateral symmetry
Exoskeleton (chitin)
Jointed appendages – which allow for more flexibility

5. Arthropod Senses Antennae - detects movement, sound, and chemicals
Pheromones – communication chemicals
May have 2 compound eyes and 3 to 8 simple eyes
Simple eyes w/ one lens used to detect light
Compound eyes w/ many lenses used to detect movement and color

6. Arthropod Body Systems
Well developed nervous system
Open circulatory systems w/ one or more hearts
Complete digestive system w/ mouth, stomach, intestine, and anus

7. Other Systems Malpighian tubules remove waste
Good muscular system attached to the inside of the exoskeleton
Most reproduce sexually
Internal fertilization (on land)
External fertilization (in water)

8. Parthenogenesis
Parthenogenesis - when an adult forms from an unfertilized egg (asexual reproduction)
In social insects (honeybees & ants)
unfertilized eggs (haploid) develop into the male drones
fertilized eggs (diploid) develop into the female workers and queens.
Used to increase reproduction rates.

9. Arthropod Molting Exoskeletons are heavy and cannot grow
Arthropods molt (shed their exoskeleton) in order to grow.
Most molt 4 – 7 times
They are very vulnerable during this time

10. Arthropod Segmentation
Most have three body sections:
The head, thorax, and abdomen
Some have two body sections:
an abdomen and a cephalothorax (fused head and thorax)

11. Gas Exchange Three types of respiratory structures:
Gills – found in aquatic species
Tracheal tubes – found in insects
Hollow air passageways
Spiracles are openings that allows air to enter or leave
Book lungs – found in spiders
Air-filled chambers with leaflike plates
Some diffuse air directly through the body

12. Diversity of Arthropods
Six classes of arthropods.
Arachnida, Crustacea, Chilopoda, Diplopoda, Merostomata, and Insecta
Amazing Arthropods (13 min)

13. Class: Arachnida Examples: Spiders, scorpions, mites, & ticks
North America has only two species of spiders dangerous to people
Arachnids are found throughout the world in nearly every habitat, but they reach their greatest size and diversity in warm arid and tropical regions
6 pairs of jointed appendages

14. Arachnid Characteristics
The body is divided into two parts
The anterior part, the cephalothorax
Has sense organs, mouthparts, and limbs in pairs
They do not have antenna
The first pair of limbs, the chelicerae, may form pincers or poison fangs
the second pair, the pedipalps, may serve as pincers, feelers, legs, hold reproductive parts
The other limb pairs, generally four, are used for walking.
The posterior part of the body, the abdomen
Has the genital opening
Has book lungs
Solitary except at the time of mating, when a variety of complex behavior patterns may be observed. Females may guard eggs or young, which are often born live.

17. Arachnida Spiders use extracellular digestion
All spiders spin silk, but not all make webs
Spinnerets are used to spin silk
Ticks and mites have a single fused body section
Scorpions have many abdominal segments, large pincers, and a venomous stinger on their tail

18. Spider Silk
Spider's silk is made up of chains of amino acids (protein).
Spider silk is extremely strong -- it is about five times stronger than steel and twice as strong as Kevlar of the same weight.
Spider silk also has the ability to stretch about 30-percent longer than its original length without breaking, which makes it very resilient.

19. Spider Silk
Goats are being genetically altered to produce ‘spider silk’ in their milk.
A thread of silk the diameter of a pencil could lift a 747
After a few days the web dries out and is no longer sticky. The spider eats and recycles the old web.

20. Normal x x

21. Spinnerets

23. Shown here is a close-up view of the pedipalps of a mature male Grammastola rosea (Chilean rose hair tarantula).
                                                                                          

24. Flower spider

25. Black Widow Spider (26 min)

26. Crustaceans Most crustaceans are aquatic and have gills
2 pairs antennae
All have 2 compound eyes, usually on moveable stalks
Mandibles open sideways
Some have 5 pairs of walking legs
Pill bugs are the only land crustaceans

27. Examples of Crustaceans
Crabs Crustacean Video (3 min)
Lobsters
Shrimp
Crayfish
Barnacles Barnacles (18 sec)
Water fleas (Daphnia)
Pillbugs

30. Centipedes and Millipedes
Centipedes - class Chilopoda
Millipedes - class Diplopoda

31. Centipedes
Centipedes are carnivorous and have a painful bite using fangs
Centipedes have an odd number (15-181) of body segments
One pair of legs per segment
Generally flattened
Have a pair of well developed antennae on the head

32. Millipedes Millipedes eat mostly plants
They don’t bite, but they can release a foul smelling fluid
Millipedes can have 100+ segments, each with 4 legs and two spiracles
Millipedes have more rounded bodies

33. South American Centipede Video (1 min)

35. Class: Merostomata
Horseshoe crabs are almost the same now as they were 500 million years ago during the Cambrian period and are called living fossils
They have a very effective exoskeleton

36. Horseshoe Crabs
The horseshoe crab has survived because it can go a year without eating and endure extreme temperatures and salinity
A horseshoe crab's tail, while menacing, is not a weapon. Instead, the tail is used to plow the crab through the sand and muck, to act as a rudder, and to right the crab when it accidentally tips over.

37. Horseshoe Crab Video (11 min)

38. Class Insecta The largest class of arthropods!
Insects usually mate only once or they might mate only a few times during their lifetime
They lay many eggs at once
Eggs are fertilized internally
Insecta is the most successful and diverse class of organisms on earth

39. Class Insecta Have 3 body segments Have 3 pairs of legs
Have 1 pair of antenna
Many fly
Amazing World of Insects (26 min)

44. Metamorphosis Many insects undergo metamorphosis from egg to adult
Complete Metamorphosis – egg, larva, pupa, and adult
Larva is wormlike and are called caterpillars
The pupa stage is a major change in body systems
Examples include butterflies, ants, wasps, beetles, etc.

46. Metamorphosis
Incomplete Metamorphosis – is a gradual change with three stages
Egg, nymph, and adult
Nymphs look like tiny adults
Examples are cockroaches and grasshoppers

48. Insect Metamorphosis (21 min)

50. Insect Fact and Folklore (22 min)