Phylum Rotifera. General Body Plan. Nematoda- the roundworms. Rotifer Reproduction

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1 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

2 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 Hookworm Lifecycle 800 million people worldwide 2

3 13 Trichinella spiralisencyst in skeletal muscle modify gene expression in cells 14 Pinworm: Enterobius vermicularis Most common nematode parasite; 30% in children, 16% in adults- US Scotch tape anyone? 15 Guinea worms Copepod host 5cm/day- 3 weeks 16 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 CaCO 3 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

4 19 Phylum Arthropoda: Segmentation, Specialization, and Diversification 20 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 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 23 Subph. Cheliceriformes : horse-shoe crabs, sea spiders, spiders, ticks, scorpions General Features: 2 major body segments 6 pairs of appendages w/ specializations 1 pair chelicerae ( fangs ) 1 pair sensory palps 4+ pairs of walking legs 3 Classes: Xiphosurida Arachnida, and Pycnogonida 24 Class Pycnogonida Sea Spiders Long, thin legs and body Proboscis mouth for sucking Male parental care of eggs and young 4

5 25 26 Class Arachnida: spiders, scorpions, ticks, mites Adaptations to land Waxy cuticle Gill replaced by book lungs Appendage spec. Malpighian tubules (also in insects)- metabolic wastes Sensory specializations Spinnerets: abdominal silk glands 27 Ticks and mites Its not the mites that get you 30 Subphylum Crustacea: Mostly marine but some terrestrial members Several Classes Biramous Appendage Requirements: exoskeleton Respiration Circulation Nitrogen wastes sensory 5

6 31 33 External Larval Crustaceans 35 Compound Eye 36 Class Branchiopoda Artemia, Brine shrimp 6

7 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

8 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 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

9 49 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 1 st seg.= poison claws; Carnivorous 50 Subph. Hexapoda Insect Diversity!- 1,000,000 + species 2 ancestral radiations Flight: mya Angiosperm coevolution: 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 Body plan adapted for terrestrial existence 3 segments 1. Head: fused segments oriented downwards 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 52 Insect Body Plan cont d: 3. Abdomen Tracheal system w/ spiracles (also in spiders) Malpighian tubules- nitrogenous wastes Open circulation w/ tubular heart and hemolymph Fused ventral nerve cords w/ ganglia 53 Tracheal system 54 Malpighian tubules Nitrogenous waste removal Diffusion and body breathing 9

10 55 Muscle systems 56 Insect Flight How compare to your hand? Primitive = Dragonfly like w/ non-folding wings Folding of wings opened up vast new habitats why? Beat frequencies of 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 57 Metamorphosis Primitive and Advances Insects Gradual Metamorphosis (Incomplete; hemimetabolous): cockroaches, grasshoppers. Nymphs or naiads (aquatic) Complete Metamorphosis (holometabolous): egg, larva, pupa (dormant form), adult Adaptive significance of larvae? 58 Holometabolous Monarch Butterfly Danaus plexippus 9/26 orders are holo, but = 88% of species! 10