Ch 33 - Invertebrates (PART 2 of 2)(1 slide per page)-1

Count in 1000s of species per group 103 arthropod

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Unformatted text preview: ropods ~11% * 1018 individuals (10 quintrillion) * 1,000,000,000,000,000,000 * 1.6 Billion per human Numbers represent approx. count (in 1,000’s) of species per group 103 Arthropod Success • Evolved from segmented worms – but no internal segmentation i.e. no septa • Over time segments fused and began to specialize – Most w/ 3 segments: head, cephalothorax and abdomen • Success due to: - body segmentation, hard exoskeleton, jointed appendages Trilobites had little fusing or specialization of segments Figure 33.27 (Campbell et al) Figure 33.29 (Campbell et al) 104 Arthropod Structure • 2-3 segments • Jointed appendages (many types) • Cuticle (aka exoskeleton): – – – – Made of chitin (as in fungal cell walls!) Molt (ecdysis) Desiccation resistance Muscle attachments • Well-developed sensory apparatus: – Eyes, olfactory, antennae, setae (hairs) • Complete digestive tract • Open circulatory system (will discuss in later chapter) • Efficient respiration system – Gills or tracheal system (will discuss in later chapter) • Efficient nitrogenous waste removal – Coxal gland and malphigian tubules (will discuss in later chapter) • Sexual reproduction (a few parthenogenic) – Usually unisexual (a few hermaphroditic, e.g. barnacles) – Fertilization external in many and internal in others (e.g. insects, spiders) 105 Phylum Arthropoda 1. Subphylum Chelicerata Class Merostomata 2. Subphylum Crustacea Class Arachnida 3. Subphylum Myriapoda Class Chilopoda Class Diplopoda Extant subphyla and classes 4. Subphylum Hexapoda Class Insecta 106 1. Subphylum Chelicerata (“bearing pincers”) 2 Classes: Merestomata (horseshoe crabs) and Arachnida (spiders, ticks, mites, scorpions) Ticks horseshoe crab mites scorpions spiders Sea spider (Pycnogonid) 107 Chelicerata: General Characteristics •2 main body parts: Cephalothorax and abdomen •Appendages: 6 pairs all on thora...
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This note was uploaded on 02/12/2014 for the course BIOLOGY 2011 taught by Professor Woo during the Fall '10 term at University of Central Florida.

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