Class Anostraca

• Fairy and brine shrimp• 27 trunk segments; only

anterior segments (thorax) with appendages (phyllopoda)

• Thorax and abdomen distinct only by presence of appendages

Class Branchiopoda

• Water fleas• Clear separation of tagmata

reduced; head and trunk• Mouth simple• Thoracic appendages adapted

for swimming; Abdomen lacks appendages

• Apparent segmentation lost• Body shape is different from

carapace

• Microscope slide of Daphnia

Class Malacostraca

• Large group of Crustacea (>20,000 species)

• See intro p.625 of lecture text for key features (Fig 19-19)

• General theme– 3 tagmata– Biramous, uniramous,

biramous

Order Stomatopoda

• Mantis shrimp• Depressed body• 3 tagmata• Shield-like carapace• Raptorial 1st pair thoracic

appendages• First antennae triramous• P. 627

Order Decapoda

• Largest order of Malacostraca

• Both antennae biramous

• 2 tagmata (cephalothorax and abdomen)

• Biramous, uniramous, biramous.

• Modification of first periopod in many

• Mouthparts 6, thoracic appendanges 5

• Divergence of mouthparts varies

Order Mysidacea

• Shrimp-like but not decapods because retain many primitive characteristics

• Head with 3 fused thoracic segments

• Carapace onlyy attached 1st – 3rd thoracic segments but looks like cephalothorax

• Tagmata not fused

O. Amphipoda

• Compressed body• No carapace• 3 tagmata• 1 – 2 thoracic segments fused

to head (8 thoracic segments)• Gnathopods are first two pair

thoracic appendages not fused to head

• 6 segments Ab split into two parts

O. Isopoda

• 3 tagmata• Head and 1st thoracic segment

fused• Depressed body• The 7 thoracic appendages

generally unspecialized (all look the same)

• Last Ab segment fused with telson (pleotelson)

• Remaining Ab segments (5) have biramous pleopods

• Biramous, uniramous, biramous

preserved specimens

Class Copepoda

• Body tapers anterior to posterior

• Short trunk (Th + Ab) 10 or fewer segments

• Head includes 3 fused thoracic segments

• Ab 4 segments, no appendage• Posterior extensions rami, not

uropods as in Malacostraca• 1st antennae variabe in size,

can be long• On slides

Class Cirripedia

Order

• d