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.
15.
16.
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.
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
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
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.
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)
40.
41.
42.
43.
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.
45.
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
