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1 2 Phylum Rotifera • Freshwater, freeliving (most), few marine • Linked to Lophotrochozoa? • Many habitats and shapes • Many interstitial • Roto-feeders • Telescopic; semi-flexible • Protonephridia and diffusion • Reproduction: parthenogenesis 3 General Body Plan 4 Rotifer Reproduction • Most Dioecious Ciliated Head= Corona • Some parthenogenetic Often a ringed cuticle to allow for contraction (antenna) Jawed Mastax for chewing heavy-shelled dormant egg, much yolk; dormant egg survives the winter Flame cells and bladder movie 5 6 Nematoda- the roundworms 1 7 Phylum Nematoda 8 Basic Nematode body plan • Freeliving and parasitic pseudocoelmates • Body structure: – – – – high SA:vol Complete digestive tract Separate sexes Cuticle • C. elegans: an experimental model • Parasites: 9 Pseudocoel: high hydrostatic pressure 10 Ascaris lumbricoides - The Large Human Roundworm • 1.5 Billon infected worldwide • 200K eggs/ day 11 Hook Worm: Necator americanus 12 Fig. 15.7 Hookworm Lifecycle 800 million people worldwide 2 13 Trichinella spiralis- 14 encyst in skeletal muscle modify gene expression in cells Pinworm: Enterobius vermicularis Most common nematode parasite; 30% in children, 16% in adults- US Scotch tape anyone? 15 Guinea worms 16 • Copepod host • 5cm/day- 3 weeks rod of Asclepius 17 Phylum Arthropoda: “jointed foot” • Evolutionary Origin: Analogous or homologous to annelids? • Evolutionary Trends 1. Specialization of segments 2. Loss or fusion of body segments (tagmata) 3. Increased cephalization • Unique Arthropod Features 1. Jointed appendages- Legs!! 2. Exoskeleton 3. Reduced coelom 4. Ecdysis (molting) and hormonal control 5. Open circulatory system 6. Gills, book lungs or trachael tubes 7. Tracheal system 18 Exoskeleton • Protective yet flexible, in many ways • Protein layers are bound with the polysaccharide Chitin. • Lightweight, tough, flexible. • Can also have CaCO3 • Stable and hard surface to attach muscle – Effective levers for efficient and fast motion. • Made into myriad tools. • But, limited by size…can’t get too big, at least on land. 3 19 Phylum Arthropoda: Segmentation, 20 Specialization, and Diversification Modern Arthropods: 4 main evolutionary lines…a divergence into 4 variations on a common theme. • Arthropod Subphyla: – Subph. Trilobitamorpha – Subph. Cheliceriformes – Subph. Crustacea – Subph. Hexapoda – Subph. Myriapoda 21 Molting- Ecdysis • Problem- How grow in an armored suit? • Well studied hormonal control • Re-absorption of old inner cuticle • New soft cuticle formed • Old “shell” left behind 23 22 Subphylum Trilobita: extinct • • • • Extinct for over 200 my 2 cm to almost 1 meter in length Segmentation with some fusion Basic body plan: cephalon, thorax (3 lobes), pygidium • Segmental specialization but little specialization in appendages 24 Subph. Cheliceriformes : horse-shoe crabs, sea spiders, spiders, ticks, scorpions • General Features: – 2 major body segments – 6 pairs of appendages w/ specializations • • • • Class Pycnogonida Sea “Spiders” Long, thin legs and body Proboscis mouth for sucking Male parental care of eggs and young • 1 pair chelicerae (“fangs”) • 1 pair sensory palps • 4+ pairs of walking legs • 3 Classes: Xiphosurida Arachnida, and Pycnogonida 4 25 26 Class Arachnida: spiders, scorpions, • Adaptations to land – – – – – – 27 29 Ticks and mites Its not the mites that get you… ticks, mites Waxy cuticle Gill replaced by book lungs Appendage spec. Malpighian tubules (also in insects)- metabolic wastes Sensory specializations Spinnerets: abdominal silk glands 28 30 • • • • Subphylum Crustacea: Mostly marine but some terrestrial members Several Classes Biramous Appendage Requirements: exoskeleton – – – – Respiration Circulation Nitrogen wastes sensory 5 31 33 External 32 34 Larval Crustaceans 35 Compound Eye 36 Class Branchiopoda Artemia, Brine shrimp 6 37 Class Ostracoda 38 Class MaxillopodaCopepods • Mating displays 39 Class MaxillopodaCirripedia- Barnacles 40 • Largest class of crustaceans • Most common orders: Longest penis relative to body height10X 41 Class Malacostraca – Isopoda- dorsoventral flattened – Amphipoda- laterally flattened – Euphausia- krill – Decapoda- crabs and shrimp – Stomatopoda- mantis shrimp Isopods 42 Amphipods 7 43 45 44 Amphipods 46 Euphausia Caprellid “shrimp”-amphipods Decapods • 2 body parts: fusion and segmentation • Cephalothorax: Head: 5 pairs of appendages: antennae, mandibles, maxillae. Thorax: 3+ pairs of walking legs • Abdomen: special appendages for locomotion and reproduction. 47 48 Order Stomatopoda Mantis Shrimp Phylum Arthropoda video • they have stereo vision with just one eye; • each eye is up on a stalk, with a wide range of motion; • stomatopods have up to 16 visual pigments (in contrast, we humans have three—red, blue, and yellow); • stomatopods can see ultra-violet and infra-red light, and some can even see polarized light. • Subph. Hexapoda – Insect success • Insect Body plan • Growth and Development • Social Behavior and Communication • Subph. Myriapoda – Class Diplopoda – Class Chilopoda Raskoff 8 49 50 Subph. Myriapoda: • All terrestrial – Class Diplopoda- Millipedes • Up to 200 Seg.; two pair of legs/seg (fusion?) • Herbivores – Class Chilopoda- Centipedes • Up to 177 Segments; one pair of legs/seg • 1st seg.= poison claws; Carnivorous Subph. Hexapoda Insect Diversity!- 1,000,000 + species 2 ancestral radiations • Flight: 245-360 mya • Angiosperm coevolution: 65-145 mya • Reasons for success? – 1.Small size – 2.Specialization reduces competition – 3.Metamorphosis: intraspecific specialization, reduced competition – 4.Flight • Light skeleton Fossils from late Jurassic (China) 51 Insect Success: the Insect Body Plan 52 3. Abdomen – Body plan adapted for terrestrial existence – 3 segments – – – – • 1. Head: fused segments oriented downwards Insect Body Plan cont’d: Tracheal system w/ spiracles (also in spiders) Malpighian tubules- nitrogenous wastes Open circulation w/ tubular heart and hemolymph Fused ventral nerve cords w/ ganglia – Sensory - 1 pair compound eyes, 2-3 pair simple eyes, 1 pair antennae – Feeding - mandibles and maxillae • 2. Thorax: locomotion - 3 pairs legs and wings 53 Tracheal system 54 Malpighian tubules Nitrogenous waste removal Diffusion and “body breathing” 9 55 56 Muscle systems • • • • • Primitive = Dragonfly like w/ non-folding wings Folding of wings opened up vast new habitats…why? Beat frequencies of 1000+ bps! Nerve vs. myogenic impulse Fulcrum/ seesaw analogy- small muscle movement=big wing flap • Ability- Low to high; hover, dart. Fly is better than any bird- hover, fly upside down, turn in 1 body length! Fastest-25 mph. Very few gliders How compare to your hand? 57 Insect Flight 58 Metamorphosis Primitive and Advances Insects Holometabolous Monarch Butterfly Danaus plexippus • Gradual Metamorphosis (Incomplete; hemimetabolous): cockroaches, grasshoppers. Nymphs or naiads (aquatic) • Complete Metamorphosis (holometabolous): – egg, larva, pupa (dormant form), adult Adaptive significance of larvae? 9/26 orders are holo, but = 88% of species! 10