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