arthropods presentation

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

2. 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

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

4. 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)

5. 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.

6. 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

7. 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)

8. 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

9. Diversity of Arthropods
 Six classes of arthropods.
 Arachnida, Crustacea, Chilopoda,
Diplopoda, Merostomata, and Insecta

10. 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

11. 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.

12. 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

13. 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.

14. 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.

15. 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

16. Examples of
Crustaceans
 Crabs
 Lobsters
 Shrimp
 Crayfish
 Barnacles
 Water fleas (Daphnia)
 Pillbugs

17. Centipedes and
Millipedes
 Centipedes - class Chilopoda
 Millipedes - class Diplopoda

18. 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

19. 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

20. 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

21. 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.

22. 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

23. Class Insecta
 Have 3 body segments
 Have 3 pairs of legs
 Have 1 pair of antenna
 Many fly

24. 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.

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