Biology 
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What percentage of animals belong to the
Phylum Arthropoda?
◦ 2/3, 67%
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List some examples of arthropods:
◦ Lobsters, crabs, spiders, and insects
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Like annelids, arthropods are segmented
animals.
Body segments bear jointed extensions called
appendages such as legs and antennae.
What does “arthropod” mean?
◦ Jointed foot
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Describe the exoskeleton of arthropods. What
is the function of each layer of the
exoskeleton?
◦ Outer layer: repels water and helps prevent
dessication
◦ Middle layer: provides the primary protection
◦ Inner layer: provides flexibility at the joints
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What is a compound eye?
◦ An eye composed of many individual light
detections, each with its own lens
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What is molting?
◦ The process by which an arthropod sheds its
exoskeleton and develops a new one.
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Identify the difference between chelicerae and
mandibles.
◦ Chelicerae-pincerlike mouth parts
◦ Mandibles- jawlike mouth parts
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What are the five main subphyla of
arthropods?
◦ Trilobita, Crustacea, Chelicerata, Myriapoda, and
Hexapoda
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What characteristics are shared by most or all
crustaceans?
◦ Have two pairs of antennae and paired appendages
(some branched).
◦ Most have mandibles and a nauplius larva.
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What is the most important role of copepods
in marine ecosystems?
◦ Abundant in the plankton and serve as a food
sources
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What are some examples of terrestrial
crustaceans?
◦ Sow bugs and pill bugs
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Why do terrestrial crustaceans only live in
moist environments?
◦ They lack adaptations for conserving water
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Crayfish
◦ 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.
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List the major characteristics of arachnids:
◦ Have a cephalothorax and abdomen.
◦ Cepalothorax usually has 6 pairs of jointed
appendages:
 Chelicerae, pedipalps, and 4 pairs of walking legs
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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.
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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.
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Name two ways in which scorpions differ
from spiders:
◦ Scorpions have large pincerlike pedipalps and a
stinger at the end of their abdomen
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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.
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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.