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Arthropoda. 5 major lines of arthropod evolution: Trilobitamorpha Cheliceriformes a. Merostomata b. Arachnida Crustacea Hexapoda a. Entognatha b. Insecta Myriapoda. Class Crustacea. Crustacea. 2 pairs of antennae Nauplius larvae 45,000 spp 6 subclasses
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Arthropoda 5 major lines of arthropod evolution: • Trilobitamorpha • Cheliceriformes a. Merostomata b. Arachnida • Crustacea • Hexapoda a. Entognatha b. Insecta • Myriapoda
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
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)
subC Branchiopoda • “gill foot” • O. Cladocera = Daphnia • Major component of FW plankton • Diel vertical migrations • Parthenogenic, ephippia, cyclomorphic, • O. Anostraca= fairy shrimp, brine shrimp
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
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
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
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