4/12/2011
Ecdysozoa Ecdysozoa
• Ecdysis = molt • Phylum Nematoda (Roundworms) – Shed outer covering: cuticle (exoskeleton) – Body not segmented – Longitudinal muscles – Pseudocoelomate – Sexual reproduction 100,000 eggs/day Zygotes resistant
Ecdysozoa Ecdysozoa
• Phylum Nematoda (Roundworms) • Phylum Arthropoda – Found in most • 1,000,000,000,000,000,000 aquatic environments • Over 1 million described species – Caenorhabditis elegans model organism – Segmented Body – m – Parasites – Hard Exoskeleton • Example: Trichinella spiralis – Jointed Appendages • Commandeer host cell function • First noted in Cambrian Explosion
Ecdysozoa Ecdysozoa
• Phylum Arthropoda • Chitinous Exoskeleton • Must shed to grow – Dangerous, energetica lly expensive • Benefits – Protection – Muscle attachment – Prevents desiccation – Structural support
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Ecdysozoa Ecdysozoa
• Phylum Arthropoda • Phylum Arthropoda • Open Circulatory System • Subphylum Cheliceriformes – Hemolymph into hemocoel – Spiders, ticks, scorpions, horseshoe crabs – HlHemocoel replaces coelom • Subphylum Myriapoda – Millipedes, centipedes • Gas Exchange • Subphylum Hexapoda – Gills in aquatic species – Insects, springtails – Holes for respiration in • Subphylum Crustacea terrestrial species – Crabs, lobsters, shrimp
Ecdysozoa Ecdysozoa
• Subphylum Cheliceriformes • Subphylum Cheliceriformes – Have chelicerae (feeding appendage) – Arachnids • Often pincers or fangs • Pedipalps – No antennae – Most have simple eyes • Single lens – Most are arachnids
Ecdysozoa Ecdysozoa
• Subphylum Cheliceriformes • Subphylum Cheliceriformes – Arachnids – Arachnids • Book Lungs
Horseshoe
2 4/12/2011
Ecdysozoa Ecdysozoa
• Subphylum Myriapoda • Subphylum Hexapoda (insects etc.) – Millipedes and Centipedes – Most speciose group of life – Terrestrial; have antennae – Mainly terrestrial and freshwater – Flight • Wings from exoskeleton • Evolved once – Flowering plants
Ecdysozoa Ecdysozoa
• Subphylum Hexapoda (insects etc.) • Subphylum Hexapoda (insects etc.) – Metamorphosis – Importance to humans Incomplete • Disease vectors • Plant pests Complete
Ecdysozoa
• Subphylum Crustacea – Marine counterpart to insects • Also freshwater and terrestrial members – Up to 19 pairs of appendages • Including on abdomen – 2 pairs of antennae
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