Arthropods
The Armored Achievers
pp. 125-131
ArthropodLargest phylum with 1 million species
(3/4 of all animals on earth)Segmented bilateral symmetryExoskeleton that must be molted in
order to growJointed appendagesBlood-vascular systemMostly internal sexual reproduction
subphylums
S u b p h ylu mTrilob ita(extin c t)
S u b p h ylu mU n iram ia
(1 )
S u b p h ylu mC h e lice ra ta
(2 )
S u b p h ylu mC ru s tacea
(m os t)
S u p erp h ylu mA rth rop od a
Uniramia - Class Insecta
3 pairs of legs largest & most
diverse group on earth
rarely in the sea but live at the water’s edge
Ex. Water strider
Subphylum Chelicerata
C lassM eros tom ata
C lassP ycn og on id a
S u b p h ylu mC h e lice ra ta
Class Merostomata
“Living fossils” NW Atlantic, Gulf,
Japan, Korea shallow, soft bottoms Ex. Horseshoe crab
(Limulus polyphemus)
carapace mouth
Inhalent current
Exhalent current
Repiratory chamber
abdomen
Book gills
Class Pycnogonida
1mm - 40cm pole to pole narrow body,
proboscis, 4 very long legs
males carry the eggs Ex. Sea Spiders
Subphylum Crustacea
35,000 speciesPrimarily marine, some freshwater,
semi terrestrial, terrestrialUse maxillae for filter – suspension
feedingGills – adapted to live in water2 pair of antennae for sensory
Classes of Crustacea
C lassC irrip ed a
C lassC op ep od a
C lassM alacos traca
S u b p h ylu mC ru s tacea
Crustacean classes
Subphylum Crustacea
Class Maxillopoda
ClassMalacostraca
ClassMaxillopoda
SubclassCirripedia
SubclassCopepoda
Subclass Cirripedia
Free-swimming larva
Cement glands attach adult form to substrate (sessile)
Hermaphroditic (long coiled penis)
Ex. Barnacles
cement
gland
cirri
Subclass Copepoda
Most abundant plankton, largest protein source (1st level consumer)
Most are free-swimming but some are parasitic
First antennae long for drag
Planktonic larva of many crustacean
Ex. copepods
Class Malacostraca
14 segments + a telsoncontains over half of all known
crustaceans
Orders of Malacostraca
ord eram p h ip od
ord erisop od
ord erd ecap od
C lassM alacos traca
Order Isopoda
Bottom dwellers (deep to intertidal)
Herbivorous scavengers
Ex. Pillbugs on land, gribbles in ocean
Order Amphipod
burrowing in sandy and muddy sediments
usually flattened from side to side
three pairs of short tail limbs are used to flick them out of danger
decapods
‘10 legs’ largest 5 pair of walking legs -
1st pair heavier with pinchers (cheliped)
Ex. Crayfish, lobster, crab, shrimp
Callinectes sapidus