Biology | Arthropoda » Phylum Arthropoda, Notes

Source: http://www.doksinet PHYLUM ARTHROPODA “joint” “footed” animals Source: http://www.doksinet Reticulitermes Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Termite Fortress Source: http://www.doksinet 0.2 mm Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Coconut Crab Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet hellgrammite Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Dust Mite Source:

http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Spider Crab holding man Source: http://www.doksinet Zoologists Are Interested in Embryology WHY? Arthropods are “EUCOELOMATE PROTOSTOMES” Source: http://www.doksinet Deuterostomes Protostomes e.g Echinoderms Vertebrates e.g Molluscs Annelids Arthropods Source: http://www.doksinet Deuterostomes Protostomes e.g Echinoderms Vertebrates e.g Molluscs Annelids Arthropods Source: http://www.doksinet Arthropods exhibit metamerism 3 3P3 Phyla Source: http://www.doksinet insects Origin (Chapter 9) “if my theory be true, it is indisputable that before the lowest Silurian stratum the world swarmed with living creatures.” “Cambrian Explosion” Source: http://www.doksinet ARTHROPOD SUCCESS . WHY?? * * * Insects 750,000 named species 30 million total ?? Source: http://www.doksinet 1 Reason for Success: the Exoskeleton = Cuticle - protective -

allows flexibility & mobility - versatile Source: http://www.doksinet “Quads” Mobility Grasshopper Hind leg “Hamstrings” human elbow joint Source: http://www.doksinet Joint-Muscle Similarity? Source: http://www.doksinet Arthropod Cuticle Layered Protein Endocuticle Layered Glycoprotein Source: http://www.doksinet The “glyco” in glycoprotein: CHITIN Chitin is a polysaccharide similar to cellulose: Light weight Mechanically tough Chemically inert Unmodified Chitin: clear, flexible, resilient Source: http://www.doksinet Contrasting Cuticles Source: http://www.doksinet Contrasting Cuticles Source: http://www.doksinet Contrasting Cuticles Source: http://www.doksinet Cuticle Modifications for Toughening e.g, Grasshopper thorax Exocuticle becomes “tanned” or sclerotized (increased cross-linking within & between glycoprotein layers) e.g, Crab “shell”, lobster claw Procuticle becomes impregnated with Ca++ salts Source:

http://www.doksinet Cuticle Modifications for Waterproofing Insect Problem: Dessication - small size - air is dessicating - cuticles not water-tight CUTICLE WAX GLAND Solution??? Source: http://www.doksinet Structure of a WAX O C Fatty Acid O CH2 CH2 CH2 CH2 (CH2)n (CH2)n CH2 CH2 CH3 CH3 Alcohol Source: http://www.doksinet Source: http://www.doksinet Pillbugs are land crustaceans!! NO WAX Source: http://www.doksinet Arthropod cuticles have 1 BIG drawback They don’t expand to allow growth!!! Vertebrate Bone Growth RADICAL arthropod solution: the MOLT Source: http://www.doksinet Source: http://www.doksinet http://www.youtubecom/watch?v=rDK3IT29uoQ Source: http://www.doksinet http://www.youtubecom/watch?v=2A1i10ZIB-w Source: http://www.doksinet Ecdysone Source: http://www.doksinet Secretes Molting Fluid (chitinase, proteases) Molting Fluid attacks Endocuticle Source: http://www.doksinet Old endocuticle dissolved away Source:

http://www.doksinet Source: http://www.doksinet Phylum Arthropoda Subphylum Myriapoda “many footed” Class Chilopoda centipedes -2 legs per segment (mostly) -Predators (venom claws) -Fast Source: http://www.doksinet Subphylum Myriapoda “many footed” Class Diplopoda millipedes Source: http://www.doksinet -”1000 feet” -Secretive & slow -4 legs per segment (mostly) -herbivorous Source: http://www.doksinet Subphylum Chelicerata Class Arachnida Order Araneae Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet http://video.nationalgeographiccom/video/kids/animals-pets-kids/bugskids/leafcutter-ant-kids/ Source: http://www.doksinet Wolf Spider with egg sac Source: http://www.doksinet Phylum Arthropoda Subphylum Hexapoda Class Entognatha (springtails, snow fleas, etc.) Class Insecta “BUGS” Source: http://www.doksinet

7,000,000,000 humans on earth for every person 200,000,000 insects !! We live in “The Age of Insects” Surprise: not found in world’s largest habitat Source: http://www.doksinet Breath-taking diversity Master Niche Fillers Source: http://www.doksinet Friend and Foe The Honeybee BROWN MARMORATED STINK BUG Halyomorpha halys Source: http://www.doksinet Basic Body Plan 3 “Tagmata” (body regions) Head Thorax Abdomen Source: http://www.doksinet Body Variety Body Plan Variety Source: http://www.doksinet H T A Source: http://www.doksinet Earwig Cerci Defense Prey Capture Source: http://www.doksinet Mouthpart Variety (sponges) Source: http://www.doksinet Sensory Variety Source: http://www.doksinet Darwin saw usefulness Vision Source: http://www.doksinet Leg Variety Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet INSECT MOBILITY All insect muscles are striated! Source: http://www.doksinet Muscles

& Endoskeletons (flexion) Antagonistic Pairs (extension) Source: http://www.doksinet Muscles & Exoskeletons Antagonistic Pairs Q: Which muscle produces the leap? Source: http://www.doksinet Source: http://www.doksinet 1st in Flight??? Not Birds Not Bats Source: http://www.doksinet Flight has huge implications (foraging, reproduction, migration, escape, etc.) 24 - 26 Orders of insects 22 have winged forms Wingless orders in this group: silverfish, bristletails, proturans, and springtails Source: http://www.doksinet 2 Pairs of Wings Source: http://www.doksinet BEETLES Forewings are protective Hindwings for flight Source: http://www.doksinet “flies” – Order Diptera 2 Wings Source: http://www.doksinet Mud Dauber collecting and transporting mud Source: http://www.doksinet Spiders packed into a cell larva Mud Dauber Nests Adult Escape Holes Source: http://www.doksinet Optimal Foraging? Source: http://www.doksinet Source:

http://www.doksinet Creationist WING Argument: Only fully-formed wings could be beneficial How did Darwin respond?? Weak Flying? Gliding? Thermoregulation? Gas Exchange? Behavioral Signal? Source: http://www.doksinet Communication Function?? Source: http://www.doksinet Source: http://www.doksinet Sustainable Flight Speeds Small grasshoppers Malaria mosquitos Housefly Blowfly Honeybee Large dragonfly Deer bot fly 1.8 km/hr 3.2 6.4 11.0 22.4 30.0 40.0 !! Roughly Bolt’s Top Speed Source: http://www.doksinet Forward Thrust Downstroke AND Upstroke FLIGHT MUSCLES Direct & Indirect Source: http://www.doksinet Tergum Indirect Flight Muscle Direct Flight Muscle Sternum Bird-like Bat-like Source: http://www.doksinet Note locations of fulcrum and muscle insertion Downstroke Source: http://www.doksinet Both Muscle Groups are Indirect Source: http://www.doksinet Fulcrum yes Muscle insertion no http://www.youtubecom/watch?v=iUNRkvwIUQ0 Source:

http://www.doksinet Slow wing beats slow neuromuscular activity Source: http://www.doksinet EXAMPLE: butterflies @ 4 beats/sec Synchronous Neural Stimulation 1 action potential 1 set of muscle cell contractions NMJ 1 wing beat Source: http://www.doksinet Extreme wing speed Can nervous systems keep up?? Source: http://www.doksinet Asynchronous Stimulation e.g, some midges exceed 1000 beats/sec midge 1000 beats/sec = 1 beat per ms !! This should be IMPOSSIBLE why? Neuron refractory periods: 5 – 10 ms In other words, muscles are contracting faster than nervous systems operate !! Source: http://www.doksinet MECHANISM When the upstroke muscles contract, they stretch the downstroke muscles. Downstroke muscles respond by contracting which stretches the upstroke muscles. This antagonism may continue several cycles before a neural input is needed to keep it going. In extreme cases, 40 wingbeats have been recorded for each neural input. Source: http://www.doksinet

FLIGHT TEMPERATURES Thoracic temperature of a flying sphinx moth (Manduca sexta) mammals Source: http://www.doksinet Flying and running are energetically demanding super lungs and heart?? NO (!) (at first look) Source: http://www.doksinet Insect Respiration Source: http://www.doksinet Source: http://www.doksinet Spiracle Body wall Source: http://www.doksinet branching resembles that inside mammalian lungs Source: http://www.doksinet Source: http://www.doksinet Source: http://www.doksinet Flying insects have large aerobic requirements while having a crude OPEN circulatory system. PARADOX? How do insects “get away with” this system? Source: http://www.doksinet Danger of Dessication High SA:VOL exacerbated by flying ?? high metabolic rate? producing urine? Source: http://www.doksinet H2O Spiracles are Valved Source: http://www.doksinet Water Loss In Urine Hemolymph (blood) in the Hemocoel (body cavity) [NO CAPILLARIES] Marcello Malpighi

(1628-1694) Source: http://www.doksinet NITROGENOUS Waste Products of Animals Ammonia Urea Uric Acid Cost of Synthesis none low high Toxicity high moderate low Solubility high high Diffusion Coefficient high intermediate low 1 2 4 N per osmotic particle very low Source: http://www.doksinet Active in re-claiming water Source: http://www.doksinet Hyperosmotic Urine (U/P> 1) Significance?? What animals can produce it?? - Mammals - Birds Potent Kidneys - Arthropods (Malpighian Tubules) Source: http://www.doksinet Animal urine can be dilute or concentrated relative to body fluids U/P osmotic pressure of urine osmotic pressure of plasma INSECT DEVELOPMENT Source: http://www.doksinet Holometabolous Development (88% of all insects) Maggot Grubs Radical reconstruction Source: http://www.doksinet HEMIMETABOLOUS DEVELOPMENT A gradual metamorphosis e.g, grasshoppers, cicadas, preying mantis, mayflies, dragonflies Source: http://www.doksinet

Source: http://www.doksinet Class Insecta Order Coleoptera Lepidoptera Hymenoptera Know examples Diptera from each Order Hemiptera Homoptera Orthoptera Source: http://www.doksinet Source: http://www.doksinet Friday’s Lab Optimal Foraging by Butterflies Source: http://www.doksinet Natural selection pushes species TO BE ADAPTED to their environment. Useful traits often appear optimized. Why not maximized?? Source: http://www.doksinet Swimming in cold water Blubber: What is optimal for a seal? optimal Source: http://www.doksinet Food to stomach? Air to lungs? Blood to brain? Wouldn’t an even longer neck be better?? Source: http://www.doksinet Trade-offs? Source: http://www.doksinet How long is long enough? Source: http://www.doksinet OPTIMALITY MODEL Benefit Amount of Cost or Benefit MAX Opt “Extent” of Phenotype Cost Source: http://www.doksinet “proboscis” Flow = ΔPπr4 8lη P = pressure inside proboscis r = proboscis radius l = proboscis

length η = fluid viscosity Lab Variable Source: http://www.doksinet Source: http://www.doksinet Amount/mL Amount/mL ? Costs? Concentration SUGAR CONCENTRATIONS (%): 8.75, 175, 35, 50, & 80 (η) Source: http://www.doksinet