BIOEE 1780 1st Edition Lecture 24Outline of previous lectureI. LophotrochozoansII. FlatwormsA) TapewormsIII. AnnelidsA) EarthwormsB) LeechesIV. MollusksA) GastropodsB) CephalopodsC) BivalvesOutline of current lectureI. AnnouncementII. ArthropodsA) General characteristicsB) More on arthropodsIII. Arthropod typesA) MyriopodsB) CrustaceansC) CheliceratesD) InsectsCurrent lectureI. Announcement*Prelim next week*Reviews: Thursday 5pm, Saturday 3pm*Exam covers from Animalia onwards and all of Irby’s lecturesII. Arthropods*Most diverse group of animalsA) General characteristics*Segmented bodies (specialization of segments) *Arthropoda: “jointed foot”*Synapomorphy: jointed appendages-Antennae – sensing-Mouthparts - tasting, manipulating foodThese 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.-Claws – grabbing food-Walking legs – walking, clearly*Reduced coelom/open circulatory system-Hemocoel/hemolymph *Developed ventral nervous system (learning of leg position by headless insects) *Exoskeleton of chitin: secreted by underlying epidermisB) More on arthropods*What are the costs and benefits of an exoskeleton?-Benefits: protection, camouflage, keeps them from drying out, if damaged it is less detrimental, structural support-Costs: less gas/nutrient exchange through skin, more energy put into producing exoskeleton, exoskeleton can’t grow with them, vulnerable right after shedding, relatively heavy when large*Ecdysis: molting, the shedding of an old cuticle III. Arthropod typesA) Myriopods *Such as millipedes and centipedes (12,000 species)*2 body parts*Millipedes: vegetarians, two pairs of legs per segment; centipedes: carnivores, 1 pair of legs per segment, give birth to live youngB) Crustaceans*Mostly aquatic/marine (67,000 species)*Three-part body*Carapace*Diverse lifestyles1) Isopods*Equal footed (pill bug, tongue-eating louse [parasitic, replaces the tongue of a fish, but fish survives])2) Decapods*Ten footed (crabs, lobsters, shrimp)*Specialized appendages*Front appendages can be modified to be large pinchers, can be small and used for foodC) Chelicerates*Mostly terrestrial*2-part body*No mandibles and no antennae*Six pairs of appendages (in some, 8 legs, 2 chelicera, 2 pedipalps)1) Horseshoe crabs*Ancient (445 million years old)*Haven’t changed much since then*1 pair of chelicerae, 5 pairs of walking legs2) Arachnids*Two parts: cephalothorax, abdomen*Spiders-All predators-Chelicera modified into fangs-Silk production from abdominal silk glands (stronger than steel of the same diameter)… uses spinnerets with different types of spigots-Reproduction#Sexual cannibalism (before, during, or after copulation) #Spiders and scorpions, otherwise rare in nature#How does sexual cannibalism benefit males? He will have better quality offspring, he may be unable to find another female, can put all his energy into a single reproductive event#Females? Extra nutrients, less competition for food when young are born, ensure the male can’t mate with anyone elseD) Insects*1,000,000+ species*3-part body, six legs, antennae*Wings*Tracheae *Instar: the stage between molts*Complete metamorphosis: larva, pupa, adult-Benefits: niches*Incomplete metamorphosis: the young are just little versions of the