Download Zoology – Arthropod Unit

Chapter 18 Arthropods
Chapter 19 Crustaceans
Chap.20 Terrestrial Arthropods
1. Identify characteristics distinguishing phylum Arthropoda
2. Discuss adaptations characteristic of the phylum Arthropoda
with regard to
Body form, morphology & embryonic development
Feeding and digestion
Excretion
Movement/locomotion
Reproduction
Sensory/Motor response
Any special features unique to the phylum
3. Identify derived characteristics that contribute to the
phylogeny of phylum Arthropoda
 Arthro
= joint
 Poda = foot
 Arthropods are
named for their
jointed appendages
 All arthropods have
an exoskeleton made
of an amino sugar
called Chitin
 Appendages
in
arthropods are
modified for a
number of functions:
• Walking legs
• Mouth parts
• Antennae
• Claws
• Organs for mating
• Holding eggs
 Segmentation
is
an ancestral
characteristic
that carries over
from the
Annelids
 Note the
similarity of the
insect caterpillar
to polychaete
worms
These animals have segements in
the head and thorax region fused
together
The millipede below has segments
fused in pairs, resulting in 2 pair of
legs per “segment”
These animals have
little differentiation
between body
segments
 The
exoskeleton
provides rigid
support and
strong points for
muscle
attachment
 The exoskeleton
also forms a
protective shell
 The
exoskeleton
prevents drying
out, but also
prevents
respiration
through the skin
 The exoskeleton
provides rigid
support, but
prevents growth –
requiring molting
 Striated
muscle associated with the
exoskeleton, and smooth muscle
associated with the gut
 Reduced body cavity, filled with blood,
forming an open circulatory system
 Specialized excretory glands (coxal,
antennal or maxillary glands; malpighian
tubules)
 Specialized respiratory organs (gills,
tracheae, book lungs)
 Dorsal brain with fused ventral nerve cords
 Like
the annelids, the arthropods have a dorsal
brain, fused ventral nerve cords, and paired
nerve branches that encircle the pharynx
The exoskeleton prevents the use of the
skin as an excretory organ. In insects,
salts and metabolic wastes are removed
by Malpighian Tubules
The malpighian
tubules extend into
the hemocoel,
extract waste
materials and funnel
them into the
digestive tract for
removal
 Tracheal
system in
insects bring air
directly to tissues
 Book Lungs in
Arachnids : a series
of flattened tissues to
create surfaces for
gas exchange
 Gills in Crustaceans
are extensions of the
walking legs
 Subphylum Trilobita
• Extremely common in the early Paleozoic era,
trilobites are extinct today
 Subphylum Chelicerata
• Class Merostomata includes Horseshoe Crabs
• Class Pycnogonida includes Sea Spiders
• Class Arachnida includes spiders, scorpions, ticks
and mites
 Subphylum Crustacea
• Lobsters, crabs, shrimp, crayfish and others less
familiar
 Subphylum Uniramia
• Myriapods (Centipedes and millipedes) and Insects
Millipedes have 2 pair of
legs per segment
Centipedes have 1 pair of
legs per segment
4. Distinguish Crustaceans from other
arthropods
5. Perform a dissection of the crayfish, a
representative crustacean.
6. Identify internal and external
anatomical features of the crayfish
7. Compare and contrast Chilopods, Diplopods, and
Insects
8. Discuss adaptations for gas exchange in a
terrestrial environment as displayed in the insects
9. Discuss adaptations for excretion of metabolic
waste as displayed in the insects
10. Discuss the process of metamorphosis in insects.
10. Discuss the process of metamorphosis in insects.
11. Distinguish between complete and incomplete
metamorphosis
12. Perform a dissection of the grasshopper, a
representative insect
13. Identify internal and external anatomical features of
the grasshopper