BIOL 1050 Lecture 25 Outline of Last LectureI. SpeciesII. SpeciationIII. Phylogenies and classificationIV. DiversityOutline of Current LectureI. Animal Diversitya. Vertebratesb. InvertebratesCurrent LectureI. Animal Diversitya. Animalsi. Eukaryotic1. Animals eat other organisms2. Animals move at some life stage3. Animals are multicellularb. Symmetryi. Organisms have either bilateral symmetry or radial symmetry1. Most have bilateral (if cut in half looks like mirror image)2. Radial symmetry is like cutting a pizza, every piece is the same c. Chordatesi. Group of animals that include homo sapiens ii. Characteristics1. Notochord2. Dorsal hollow nerve cord3. Pharyngeal slits4. Post-anal tailiii. Includes1. Tunicates (mussels, barnacles)2. Lancelets (fish)3. Vertebratesd. Vertebratesi. Have a backbone and cranium (braincase)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.e. Evolution of Jaws and Finsi. Fish without jaws or paired fins1. Tail fin propels organism through water 2. Feed by attacking mouthparts to preyii. Fish with jaws and paired fins1. Paired fins provide controlled movement through water2. Jaws allow for seizing and chewing prey 3. The development of fins and jaws set the stage for the evolutionary explosion of vertebrate diversity f. From water to landi. The transition of vertebrates from life in water to life on land required overcoming three main obstacles. Four major evolutionary innovations allowed for this transition1. Problem: respirationa. Aquatic animals use gills to acquire dissolved oxygen from water. The transition onto land required the ability to breathe air2. Solution: lungsa. Gas exchange was transferred from gills to lungs, which evolved from the swim bladder found in ray-finned fishes3. Problem: gravitya. The transition onto land required structural support to resist the pull of gravity4. Solution: limbs and modified vertebratea. Limbs evolved from the jointed fins found of the underside of lobe-finned fishes. Vertebrae were modified to transmit the body weight through the limbs to the ground 5. Problem: egg desiccationa. The transition onto land required an egg that resisted drying out when exposed to air6. Solution: amniotic egga. Terrestrial animals developed a waterproof eggshell, which prevents eggs from drying out before they hatch.g. Amphibian life cyclei. Amphibians such as frogs, toads and salamanders are terrestrial vertebrates(tetrapods) with non-amniotic eggs. Most species live on land as adults, butdevelop in water1. Eggsa. Amphibians have non-amniotic eggs, which must be laid in water to prevent desiccation2. Larvaea. Amphibians spend their larval stage underwater and undergo metamorphosis to develop legs and lungs3. Adultsa. Only the adults are true land animals; however, most of the species in this group stay close to water to lay their eggs h. Reptiles vs. Birdsi. Reptiles1. Scales2. Ectothermic: body temperature is controlled by external conditions3. Snakes, lizards, turtles, crocodiles and alligatorsii. Birds1. Feathers2. Endothermic: maintains body temperature using heat from cellular respiration i. Groups of mammalsi. Mammals are endothermic vertebrates that have hair and produce milk for their youngii. Monotremes1. Lay eggs2. Milk young using hairs3. Ex. platypusiii. Marsupials1. Give birth to immature young2. Young complete development in mom’s pouch3. Ex. Kangarooiv. Placental mammals1. Placenta nourishes young in uterus2. Milk young with nipples3. Ex. Humans j. Invertebratesi. 95% of animals do not have a backboneii. Arthropods1. Characteristicsa. Segmented body with head, thorax, and abdomenb. Exoskeletonc. Jointed appendages2. Includesa. Insects (750k)b. Arachnids (60k)c. Crustaceans (52k) d. Millipedes and centipedes (10k) e. Make up 75% of species on
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