1 Arthropod Characteristic Subphylum Crustacea Crustacean

Arthropod Characteristic
= “jointed limbs”
Segmented body = metamerism
= grouped into 2/3 regions
Paired segmented appendages
Chitinous exoskeleton
Tubular alimentary canal
Coelom reduced = hemocoel
Open circulatory system
Respiration by gills, tracheae
or spiracles
Anterior ganglion, paired
connectives & nerve cords
Malphigian tubes = excretion
Separate sexes
Subphylum Crustacea
Crustacean Characteristics
economical importance since
ancient times
one of two invertebrates in
the Zodiac
30,000 described living species
From few mm - 4m
Homarus americanus 17 lbs
Mostly marine and freshwater,
few terrestrial = all depths
Some of the largest
morphological diversity =
“insects of the sea”
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Class Branchiopoda
-Anostraca ("fairy shrimp"),
Notostraca ("tadpole shrimp"),
Cladocera ("water fleas"),
Conchostraca ("clam shrimp')
- about 800 describes species
- Various aquatic environments
(brackish - fw)
- 0.2-5mm in size (microscopic)
- lifespan of up to a year
- generally filter feeders
- some considered threatened,
used in toxicology
- reproduce parthenogenically
Branchiopod Bauplan
Difficult to generalize
Fused thorax and
abdomen
Appendages =
phyllopodus
# of appendages
varies
Paired compound
and/or single median
eye
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Class Ostracoda
= “mussel shrimp”, 46 species, up to 25mm, up to 1 year
Different lifestyles (parasitic - open water), scavenger,
carnivores or herbivores
Sexual reproduction with larval stages
Body enclosed in carapace folds, adductor muscle and valves,
antennae/antennules - uniramous
Class Copepoda
up to 20mm
on every continent & every ocean
variety of diets = free living or
parasitic
! some parasites up to 33 cm
bioindicator species
cephalothorax = head & thorax;
abdomen
antennules = 1st pair uniramous,
2nd pair varies
adult females often with egg sacs
Class Branchiura
175 species, example Argulus
ectoparasites, fw, coastal and
estuarine, never ocean
=> pest in fish culture
feed on blood, sucking/rasping
mouth parts
diecious
head (carapace), 5 limb-bearing
appendages (biramous), thorax,
abdomen
antennae uniramous
2 suckers, rasping mandibles
flattened body
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Class Cirripedia
= barnacles
1220 species
2.5-30cm, shell color varies
All live attached, marine
Economically detrimental,
invasive
Ectoparasites
Filterfeeders
Gonochoristic
Nauplius and cypris larva
Balanomorpha/Lepadomorpha
Hugely modified body
Softbody surrounded by 6 plates
6 thoraic pair of legs, uniramous
Class Malacostraca
25,000 extant species, most
crustaceans
14 segments + telson and
carapace
terrestrial, marine, freshwater
intertidal down to 800 m
size difference = up to 22 kg,
1cm - 2 m
endure up to 300 Celsius
produce power of 22 caliber
bullet (mantis shrimp tail)
free living, some commensals
General Malacostracan Bauplan
7 segments
including telson
8 segments, sometimes
3 segments fused
6 segments
Antennae/antennules
mouthparts
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Biramous Appendages
Protopodite
Exopodite
Endopodite
Modified limbs on the thorax of a
crustacean arthropod
Endopodite
Gill
(exopodite)
Endopodite
Gill
Protopodite
(exopodite)
Protopodite
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