Entomology 101 Arthropod Groups Characteristics of the Phylum

Entomology 101 Arthropod Groups Characteristics of the Phylum

Entomology 101
Arthropod Groups
David J. Shetlar, Ph.D.
The “BugDoc”
The Ohio State University,
OARDC & OSU Extension
Columbus, OH
Characteristics of the Phylum
Arthropoda
•
Coelomate protostomates that posses a
segmented chitinous exoskeleton that must be
shed during growth.
•
Segments have paired appendages (e.g., legs,
antennae) that are jointed.
•
Segments are grouped into regions, called
tagmata (e.g., head, thorax, abdomen).
•
•
The nervous system is ventral
The circulatory system is open and dorsal.
© Sept, 2009, D.J. Shetlar, all rights reserved
Arthropod Groups (taxa)
The arthropods are divided into two
large groups that exist today:
The Chelicerates
and
The Mandibulates
Mandibulate Arthropod Characters:
•
Mouthparts are mandibles - normally
chewing sideways
•
•
One or two pairs of antennae
•
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Various body region arrangements cephalothorax & abdomen / head &
trunk / head, thorax & abdomen
Variable leg numbers
Insects, crustaceans & myriapods
Chelicerate Arthropod Characters:
•
Pincher-like mouthparts chelicerae - and pedipalps
•
•
NO antennae
Two body regions, usually cephalothorax & abdomen
•
•
Four pairs of legs
Horseshoe crabs and arachnids
are only living groups
Classes of Arthropods:
Chelicerates –
Class Xiphosura – horseshoe crabs
Class Arachnica – arachnids
Mandibulates –
Class Crustacea – crustaceans
Class Diplopoda – millipedes
Class Chilopoda – centipedes
Class Symphyla – garden centipedes
Class Hexapoda – insects
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Class Arachnida
• 2 body regions
• Cephalothorax
• Abdomen
Pseudoscorpion
Major Orders of Arachnids
Scorpion
•
•
Scorpiones - scorpions
Pseudoscorpiones - false
scorpions
•
Opiliones - daddy-long-legs or
harvestmen
•
•
Acari - mites & ticks
Araneae - spiders
Daddy-long-legs
Tick
(a mite)
Wolf
Spider
Order Scorpiones
pedipalps
{
2
Pseudoscorpion
chelicerae
eyes
pedipalp
Mite and Tick Body Regions
American dog tick male
pedipalps &
chelicerae
cephalothorax
abdomen
Blacklegged (deer) tick female
Clover mites
Twospotted spider mites
American dog tick female laying egg mass (1000-2000 eggs!).
Predatory mite
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Opiliones (=daddy-long-legs,
harvestmen)
Spider Anatomy
pedipalp
cephalothorax
abdomen
chelicera (fang)
cephalothorax
narrow waist
abdomen
Jumping Spider
Abdomen
Cephalothorax
Chelicera (fang)
Wolf spider with egg case
Spitting spider
Pedipalp
Tarantula
Orbweaving spider
Classes of Myriapods
Black widow with egg case
(many legged arthropods)
(all have one pair of antennae, a head region, and trunk
with many pairs of legs, use trachea)
•
•
•
Diplopoda - millipedes
Chilopoda - centipedes
Symphyla - garden centipedes
Brown recluse
(fiddleback)
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Myriapods
[one pair of antennae, head & trunk regions, trunk with many pairs of legs]
Millipede (Diplopoda)
Millipede (Diplopoda)
Two pair of legs per visible segment, attached
under body.
Centipede (Chilopoda)
Centipede (Chilopoda)
Pair of fangs under head, one pair legs per visible
segment - attached to side of body.
Symphylan (Symphyla)
[garden centipede]
Garden centipede (Symphyla)
No fangs, no eyes, legs attached to side of body.
Classes of Crustacea
Crayfish External Morphology
(mostly marine, fresh water, a few terrestrial)
(all have two pair of antennae, five or more pairs of legs,
segmented abdominal appendages, head & trunk or
cephalothorax & abdomen body arrangement, have gills)
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Isopoda - sowbugs or pillbugs
Amphipoda - sand fleas, amphipods
Cirripedia - barnicles
Decapoda - crabs, lobster, shrimp
several other minor orders
Sowbugs (Isopoda),
terrestrial crustaceans
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