LIFE 103 1st Edition Lecture 25 Outline of Last Lecture II Table Continued III Big 9 focus IV Lophotrochozoa I Platyhelminthes II Mollusca III Annelida Outline of Current Lecture V Ecdysozoa VI Nematoda VII Arthropoda VIII Characteristics of arthropods IX Arthropod diversity X Chelicerata XI Crustacea XII Insecta XIII Size of insects Current Lecture I II Clade common ancestor and all of its descendants Revisiting the last clicker question invertebrates are NOT a clade Animal taxa invertebrates III I Ecdysozoa I Loricifera II Pripula III Tardigrada IV Onychophora V Arthropoda VI Nematoda VII Defined by molecular evidence VIII An external covering cuticle or exoskeleton IX Molted with growth ecdysis These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute X XI Most diverse animal group by far Two big groups are nematodes and arthropods Nematoda roundworms 15 000 species or up to 1 million I II III IV Half parasitic half free living Motile Nearly all habitats and all elevations Important in decomposition and nutrient cycling Arthropoda arthropods many millions I II III IV V VI VII Every feeding style imaginable Motile Marine freshwater terrestrial Most successful of all animal phyla Five major groups I Myriapods first land animals centipedes and millipedes II Trilobites completely extinct group III Chelicerates spiders mites scorpions etc IV Crustaceans crabs lobsters etc V Insects moths butterflies etc All have segmentation We re just focusing on the last three Characteristics of Arthropoda I II III IV V VI VII Arthro joint Pod foot I Segmented body Paired limbs on segments Hard exoskeleton chitin Jointed appendages I Helps them move around more easily Open circulatory system hemolymph circulates through hemocoel I Humans have a closed circulatory system hemolymph carries oxygen binding molecules like hemoglobin but it moves into the body cavity Insects are the most diverse group especially beetles I An inordinate fondness for beetles J B S Haldane Arthropod diversity I II III Hexapoda most common weevils 89 Crustacea most common copapods 4 Myriapoda 1 IV V Cheliceriformes most common mites 6 Other 7 Chelicerata spiders mites scorpions etc I II III IV V Chilcerae feeding appendages often venomous Cephalothorax Abdomen 4 pairs of walking legs Pedipalps modified pair of legs used to get food and transfer sperm Crustacea crabs shrimp copepods amphipods barnacles etc I II III IV V Many pairs of walking legs Antennae 2 pairs Cephalon thorax abdomen 3 big body segments of them Copepods may be the most numerous of animals on Earth Barnacles have to get creative hermaphroditism spermcasting very large organs Insecta insects beetles butterflies ants bees cockroaches flies etc I II III IV V Abdomen thorax head Antennae only one pair Wings true flight some of the only animals 3 pairs of walking legs Metamorphosis larval stage that does not resemble the adult stage undergo this in life cycles egg becomes larvae then pupil then adult complete metamorphosis a Incomplete grasshoppers look like adults at start but get bigger Clicker question The phylum Arthropoda is made up of these living groups insects chelicerates crustaceans and myriapods Why aren t insects larger I II III IV Still pretty small Heaviest modern insect giant weta Largest modern insect stick insect Largest known insect was a dragonfly
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