LIFE 103 1st Edition Lecture 26 Outline of Last Lecture II Ecdysozoa III Nematoda IV Arthropoda V Characteristics of arthropods VI Arthropod diversity VII Chelicerata VIII Crustacea IX Insecta X Size of insects Outline of Current Lecture I Size of insects II Vertebrates III Deuterostomia IV Echinoderms V Chordata VI Gnathostomes VII Osteichthyes VIII Lobe fins IX Tetrapods X Amphibians XI Amniotes Current Lecture Why aren t insects larger 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 I II III IV V Tracheoles that oxygen goes into cells Size would make oxygen diffusion difficult More oxygen in the air in the past why there were larger insects Tracheae and tracheoles essentially ductwork allow air to circulate throughout the body oxygen diffuses into the tissues near individual cells It s an evolutionary constraint Vertebrates Chordate evolution to amniotes Deuterostomia I II Defined by molecular evidence Deuterostome development I Made up of Echinodermata sea urchins hemichordate acorn worm and chordate tunicate Echinoderms starfish sea urchins sea cucumbers 7 000 species I II III Predators and filter feeders Motile Marine Chordata chordates 65 000 species I II III All feeding styles Motile and sessile Nearly all habitats and all elevations throughout the world Chordates I II III IV V VI VII Notochord Dorsal hollow nerve chord Pharyngeal slits Post anal tail Most species diversity in the vertebrates Notochord flexible rod in chordate embryos becomes spine in vertebrates Pharyngeal slits develop into gills and eventually elements of the head jaw and ears Vertebrates I II Duplication of Hox genes possibly useful in increasingly complex body plans Bony vertebrae usually surrounding the spinal cord Gnathostomes I Jawed mouth II III IV V Jaws More gene duplication Enhanced smell and vision Lateral line system line of pores that detect pressure motion and electromagnetic waves in the water Clicker question identify the animal groups on this tree from least to most inclusive that includes the species Homo sapiens Milk Amniotes mammalia amniotic egg Amniotes Reptilia limbs with digits Tetrapods Amphibia lobed fins Lobe fins Dipnoi lungs or lung derivatives Ostelchthyans jaws mineralized skeleton Ganthostomes vertebrae Vertebrates notochord Chordates Mammalia milk amniotes amniotic egg tetrapods limbs with digits lobe fins fins with lobes Osteichthyes lungs or lung derivatives gnathostomes jaws vertebrates vertebrae chordatesnotochord Osteichthyes majority of vertebrates bony fish I II III Ossified endoskeleton Have lungs or lung derivatives Have a bony skeleton Actinopterygii I II III IV Ray finned fishes most diverse vertebrate group over 30 000 species In all aquatic habitats From 8 mm to 11 m in length Any possible aquatic niche Lobe fines Sarcopterygii I II Lobed fins with bony and muscular support Have created the bones of our arms and legs Tetrapods I II III IV 4 limbs with digits Adults lack gills Vertebrae in neck permit head movement Pelvic girdle fused to spine I Helps with walking Amphibia I II III IV Frogs and toads 5 000 species I One of the most diverse vertebrates II Global many habitats III Often specialized for leaping IV Tadpoles aquatic arvae Salamanders and newts 700 species I Northern hemisphere temperate predators II Aquatic larvae Caecilians 200 species I Burrowing soil dwelling II Tropical III Viviparous fertilize eggs in body until they develop in body and hatch out Majority of groups live in tropics Amniotes I II III IV V Amniotic egg specialized extraembryonic membrane shell Ventilate with rib cage Not tied to marine habitats can live anywhere Birds are reptiles because they descended from dinosaurs Reptilia Mammalia Reptilia I II III IV V 20 500 species Scales composed of keratin Shelled eggs on land ovoviviparity Internal fertilization Ectothermic endothermic cold blooded dependent on behavior environment warm blooded Evolution of limbless forms I If a tetrapod lacks limbs is it still a tetrapod