1. Arthropoda 5 major lines of arthropod evolution: Trilobitamorpha
Cheliceriformes
a. Merostomata
b. Arachnida
Crustacea
Hexapoda
a. Entognatha
b. Insecta
Myriapoda

2. Class Crustacea

3. Crustacea 2 pairs of antennae Nauplius larvae 45,000 spp 6 subclasses
subC Malacostraca – decapods, amphipods, isopods (60%)
subC Brachiopoda – daphnia, brine shrimp, fairy shrimp
subC Ostracoda – ostracods
subC Copepoda – copepods
subC Pentastomida – tongue worms (nose parasites)
subC Cirripedia - barnacles

4. SubClass Malacostraca
Head and thorax fused into cephalothorax
Biramous appendages
Of huge economic imptce
O. Decapoda: lobster, crab
O. Euphausiacea: krill (99M tonnes in antarctica=world harvest of all other marine life combined)

5. krill

7. subC Branchiopoda “gill foot” O. Cladocera = Daphnia
Major component of FW plankton
Diel vertical migrations
Parthenogenic, ephippia, cyclomorphic,
O. Anostraca= fairy shrimp, brine shrimp

8. ephippia

9. subC Ostracoda Look like small clams that actively swim
Head encased in bivalve carapace
Very common in FW, but also marine and some are terrestrial

10. subC Copepoda
Major component of plankton in both marine and FW habitats
Single eye “Cyclops”
Pair of egg sacs trail behind
Parthenogenic
Most important herbivores in the ocean
About 25% are parasitic

11. subC Pentastomida
All tongue worms are internal parasites of the respiratory passages of vertebrates (reptiles mostly)
Yet fossil record predates vertebrates!
Often have intermediate hosts
Ingested by final host and migrate to the respiratory tract
Position within Arthropoda (and Crustacea) a recent consensus

12. subC Cirripedia = hairy feet (used for filter feeding)
Sedentary, secrete calcareous shell
Initially classified as molluscs (have tissues analogous to a mantle, mantle cavity)
O. Thoracica = the barnacles
Some cirripeds in other orders are parasitic