ExoskeletonSegmented BodyMuscles & LocomotionRespirationSpiracles: (holes in exoskeleton) connected to tracheal tubes, connected to lungs or gills.DigestionChelicerata: FeedingChelicerata: ReproductionSensory SystemsClass Arachnida: Web SpinningSub-Phylum: CrustaceaBIO SCI 100 1st Edition Lecture 11Outline of Last Lecture I. DiversityII. Land Snail AnatomyIII. Freshwater Clam AnatomyIV. Molluscs in Our LivesV. Invasive Species: Zebra MusselsOutline of Current Lecture I. Phylum ArthropodaII. Class MalacostracaIII. Class ArachnidaIV. Class MerostomataCurrent LectureI. Phylum Arthropoda: Part 1- Fossils from mid cambrian~ 500 mya.o Ex: trilobites.- Extremely high diversity.- Over 1 billion species described.- Sub-phylum Chelicerata:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Class Merostomata Ex: horse shoe crab.o Class Arachnida Ex: spiders, scorpions, ticks, and mites.- Sub-phylum Crustacea:II. Class Malacostracao Ex: lobsters, crabs, shrimp.- Arthorpodameans “jointed foot”.- Eucoelomate.- Triploblastic.- Bilateral symmetry.- Dioecious.- Terrestrial &aquatic.- Cuticle exoskeleton.- Body segments with paired appendages.Exoskeleton- Protective cuticle secreted by the epidermis.o Protection: predators &dehydration.o Flexible.o Lightweight.o Support.- Made of chitin.- Does not grow with organism.o Must be shed to grow a larger exoskeleton, a process called molting.o Usually 4-7 times before adult stage.Segmented Body- Tagmata: body segments that are fused into groups.- 3 groups: head, thorax, abdomen.- 2 groups: cephalothorax, abdomen.- Cephalothrax: head &thorax regions combined.- Segmentation and paired appendages allows more efficient locomotion.Muscles & LocomotionAdvanced Muscular System:- Striated muscles attach to cuticle.- Individual muscles and antagonistic pairs.- Allow large range of motion for purposes of walking, hopping, and flying.- Also allow more complex manipulation of food items.Respiration- Spiracles: (holes in exoskeleton) connected to tracheal tubes, connected to lungs or gills.- Efficient: delivers oxygen directly to tissues&cells.- Makes higher metabolic rates possible.Digestion- Digestive system is and divided into three main regions:o foregut: for storage and grinding.o midgut (stomach): for enzymatic digestion.o hindgut_: intestine (absorption),& anus for (excretion).Sub-Phylum Chelicerata:Diversity:Foregut MidgutHindgut- Ex:Horseshoe crabs, spiders, scorpions, ticks, and mites.- Have 8walking legs.- Have 8simple legs.- Most have 4 feeding appendages .- 2 pedipalps.- 2chelicera,may have fangs.- 2 Tagmata:o Cephalothorax.o Abdomen.- No mandibles or antennae to suck liquid food from prey.Chelicerata: Feeding- Many Use Venom to Kill Prey:o Spiders: inject venom via fangs in chelicera, kills prey. o Venom is digestive enzymes(liquefies the prey's insides), which spider ingests.o Scorpions: Venom injected via stinger.Chelicerata: Reproduction- Dioecious.- Horseshoe crabs and spiders lay eggs.- Most scorpions give birth to live young, which they carry on their backs until first molt.- Spiders: male deposits sperm on web, picks it up with pedipalpand inseminates female.- Females lay eggs in a cocoon.III. Class Arachnida- Spiders, scorpions, ticks, mites.- Mostly terrestrial predators.o Some are parasites (mites, ticks).- Spiders: pedicel separates cephalothorax and abdomen.- Spiders: pedipalpscatch prey and chelicerahave fangs.- Scorpions: no pedicel.o Abdomen has “stingers”.- Scorpions: 'pincer-like' pedipalps, no fangs on chelicera.Major OrgansSensory Systems- Nervous system:brain, and longitudinal nerve cords that branch.- 8 simple eyes.- Sensory setae for touch.Class Arachnida: Web Spinning- Spinnerets are connected to abdominal silk glands.- Secretes a liquid protein; dries on contact with air =>spider silk.- Stronger than steel cable or same diameter.o Can stretch 20% of total length before breaking.- Webs used to catch prey and create egg sacs.IV. Class Merostomata- Horseshoe crabs: only 5 living species.- Gills.- Shallow marine water.- Ancient: unchanged from the Cambrian period.Sub-Phylum: CrustaceaV. Class Malacostraca- Examples: Crabs, lobster, shrimp & pill bugs.- 2 pairs of sensory appendages:antennae and antennules.- 3 feeding appendages: mandibles, maxillae.- Maxillipedl: (no chelicera).- Chelipods: first pair legs for food capture.- Plus 8 walking legs.- Tagmata:o Cephalothorax &abdomen.- Respiration via gills beneath carapace.Class Malacostraca: Feeding - Chelipedsused in food capture.- Maxillipedshold and crush food.- Mandibles&maxillae for ingesting and shredding food.Class Malacostraca: Reproduction - Dioecious.- Fertilization is external.- Females typically carry eggs with her until hatching.- Young go through a series of molts before reaching adult