Biology 
What percentage of animals belong to the
Phylum Arthropoda?
◦ 2/3, 67%
List some examples of arthropods:
◦ Lobsters, crabs, spiders, and insects
Like annelids, arthropods are segmented
Body segments bear jointed extensions called
appendages such as legs and antennae.
What does “arthropod” mean?
◦ Jointed foot
Describe the exoskeleton of arthropods. What
is the function of each layer of the
◦ Outer layer: repels water and helps prevent
◦ Middle layer: provides the primary protection
◦ Inner layer: provides flexibility at the joints
What is a compound eye?
◦ An eye composed of many individual light
detections, each with its own lens
What is molting?
◦ The process by which an arthropod sheds its
exoskeleton and develops a new one.
Identify the difference between chelicerae and
◦ Chelicerae-pincerlike mouth parts
◦ Mandibles- jawlike mouth parts
What are the five main subphyla of
◦ Trilobita, Crustacea, Chelicerata, Myriapoda, and
What characteristics are shared by most or all
◦ Have two pairs of antennae and paired appendages
(some branched).
◦ Most have mandibles and a nauplius larva.
What is the most important role of copepods
in marine ecosystems?
◦ Abundant in the plankton and serve as a food
What are some examples of terrestrial
◦ Sow bugs and pill bugs
Why do terrestrial crustaceans only live in
moist environments?
◦ They lack adaptations for conserving water
◦ What are the functions of the mandibles and
chelipeds on a crayfish?
 Mandibles are used for chewing
 Chelipeds are used for capturing food and defense.
◦ What structural adaptations of crayfish promote
effective respiration in water?
 Walking and branches of maxillae circulate water over
the gills.
◦ Crayfish (continued):
◦ Describe the type of circulation found in a crayfish.
 Open circulatory system; the heart pumps hemolymph
into several large vessels. Hemolymph then enters the
spaces w/in the body where it bathes the tissues.
Hemolymph returns to the gills where it exchanges O2
and CO2. Then, the hemolymph returns to the heart.
List the major characteristics of arachnids:
◦ Have a cephalothorax and abdomen.
◦ Cepalothorax usually has 6 pairs of jointed
 Chelicerae, pedipalps, and 4 pairs of walking legs
Describe the functions of pedipalps:
◦ Aid in holding food and chewing
◦ In spiders, they transfer sperm from the male to the
female’s seminal receptacle.
Describe three ways in which spiders are
adapted to catching prey:
◦ Some spiders spin webs to trap prey.
◦ They also have chelicerae modified as fangs that
inject venom.
◦ Spiders can also immobilize their prey by wrapping
them in silk.
Name two ways in which scorpions differ
from spiders:
◦ Scorpions have large pincerlike pedipalps and a
stinger at the end of their abdomen
How do mites and ticks differ?
◦ Mites are usually less than 1 mm in length, while
ticks are a few millimeters to 3cm in length. Mites
can be free living, but ticks can only be parasites.
How do millipedes and centipedes differ?
◦ Millipedes are herbivorous, have rounded bodies,
and have two pairs of legs on most segments.
◦ Centipedes are carnivorous, have flattened bodies,
and have one pair of legs on most segments.