DIVERSITY, CLASSIFICATION & EVOLUTION PART II

1. VERTEBRATE ZOOLOGY (VZ Lecture02 – Spring 2012 Althoff - reference PJH Chapters 1-2) DIVERSITY, CLASSIFICATION & EVOLUTIONPART II

2. 1 2 Branchiostoma 4 Amphioxus-like nonvertebrate chordate 3 1 2 Hypothetical primitive vertebrate 4 3 Fig. 2-4 p4 PJH

3. A Basics of Vertebrate Design (reference Table 2.1 PJH) Generalized Nonvertebrate Primitive Vertebrate FEATURE No cranium Cranium Simple brain Tripartite brain No specialized sense organs Multicellular sense (except photoreceptors) organs (eye, nose, inner ear) Poor distance sensation Improved distance (but sensitive skin) sensation; lateral line system No electroreception Electroreception in primitive form

4. HINDBRAIN MIDBRAIN FOREBRAIN ________________ BRAIN

5. B Basics of Vertebrate Design (reference Table 2.1 PJH) Generalized Nonvertebrate Primitive Vertebrate FEATURE Gill arches for filter feeding Gill arches support (respiration by diffusion) gills used for respiration Numerous gill slits & arches Few gill slits (6-10 (up to 100 per side) per side); gill filaments complex Pharynx not muscularized Pharynx muscularized (w/ exceptions) (specialized) Water moved through pharynx Water moved by and over gill arches by active muscular ciliary action pumping Gill arches made of collagen Gill arches made of mucoscleroproteins cartilage—allows elastic recoil & thus aids in pumping

6. C Basics of Vertebrate Design (reference Table 2.1 PJH) Generalized Nonvertebrate Primitive Vertebrate FEATURE Gut not muscularized, food Gut muscularized, passage by ciliary action food moves by peristalsis Digestion of food is intracellular; Digestion of food is Cells lining gut take in extracellular; individual food particles Enzymes poured onto food in gut lumen No discrete liver and pancreas; Discrete liver and midgut cecum or diverticulum pancreatic tissue is probably homologous to both

7. D Basics of Vertebrate Design (reference Table 2.1 PJH) Generalized Nonvertebrate Primitive Vertebrate FEATURE No true heart (ventral pumping Ventral pumping heart structure (vessels) 3-chambered peristalsis No neural control of pumping Neural control of pumping (except hagfishes) Open circulatory system, minimal Closed circulatory capillary system system Blood not specifically involved Blood specifically in transport of O2 and CO2 involved in O2 & CO2 transport No red blood cells or respiratory Red blood cells with pigments hemoglobin

8. E Basics of Vertebrate Design (reference Table 2.1 PJH) Generalized Nonvertebrate Primitive Vertebrate FEATURE No specialized kidney; coelum Specialized glomerular filtered by flame cells kidney; segmental structures along dorsal body wall Flame cells empty into atrium Empty to ‘outside” via then out atriopore archinephric ducts leading to cloaca Body fluid concentrations and Body fluids more dilute ionic composition = seaH20 than seawater No kidney present to regulate Kidney regulates fluid volume, where nitrogen excretion occurs

9. GLOMERULAR STRUCTURE IN KIDNEY FLAME CELL Note: example here is of planaria (non-chordate)

10. F Basics of Vertebrate Design (reference Table 2.1 PJH) Generalized Nonvertebrate Primitive Vertebrate FEATURE Notochord provides main support Notochord provides for body muscles main support for body muscles plus vertebral elements around nerve cord (except hagfishes) Myomeres with simple V-shape Myomeres more complex W-shape No lateral fins or medial fins Primitively, no lateral beside tail fin fins. Caudal fin has dermal fin rays. No dorsal fins Dorsal fins present (except hagfishes)

11. AMPHIXOUS LAMPREY SHARK (DOGFISH) BONY FISH (perch) Fig. 2-10 p33 PJH

12. Embryology& Germ Layers • All animals except sponges (Porifera) form distinct tissue (germ) layers. For vertebrates, 3 germ layers form during embryonic development • 3 layers: ectoderm, mesoderm, endoderm • Each has enabled refinements in organ-systems

13. Pharyngula state of embryonic development ECTODERM Gut endoderm ECTODERM Fig. 2-5 p26 PJH

14. Germ Layers: ECTOderm • forms superficial layers of skin in adults, linings of most anterior and most posterior parts of the digestive tract and the nervous system (including most of the sense organs…eyes and the ear • How can it be the “ecto” layer if it lines much of the digestive tract?

15. Germ Layers: ENDOderm • forms balance of digestive tract as well as lining of glands associated with the gut (i.e., pancreas, gall bladder, liver). Linings of most respiratory surfaces of vertebrate gills and lungs

16. Germ Layers: MESOderm • The last of the 3 germ layers to appear during embryonic development • Forms everything else: muscles skeleton (including notochord) connective tissue circulatory system urogenital system • Further along in development, mesoderm forms the coelom (body cavity) pleuroperitoneal & pericardial cavities… in gut the cavity is lined by mesenteries

17. Pharyngula Stage (Fig. 2-5, p26) • In most vertebrates, the linings of the pharyngeal pouches result in 6 or more glandular structures including…. Lymphatic system thymus gland parathyroid glands carotid bodies tonsils • During this stage, the embryo is a mix of ______________ and ___________________components

18. Pharyngula Stage and beyond • Gives rise to _______________ (running from the head end to the tail end • __________ eventually form: dermis of the skin striated muscles of the body used in locomotion portions of the skeleton (vert. column & back of head)

19. 5 Tissue Types in ADULT vertebrates • Epithelial • Connective • Vascular (blood) • Muscular • Nervous Most of these tissue have, as fundamental component, the fibrous protein ________. Other key component fibrous proteins that may be present include _________ and _________.

20. Integument • External covering of vertebrates • Makes up ________ of body weight in most vertebrates…more in armored species • Includes skin and deriatives (i.e., glands, scales, dermal armor, and hair) • 3 layers: epidermis—outer layer dermis—middle “unique” layer subcutaneous tissue layer (hypodermis)

21. Important Mineral • Unique to vertebrates: type of mineral called ________________. A complex compound of ____ and ____. • This mineral more resistant to acid than calcium carbonate (in mollusk shells)…an may explain how vertebrates can resist tissue damage when engaged in muscular activity that can release lactic acid into the blood

22. Mineralized tissues… • Six types possible in vertebrates: ________ (adults only, 99% of composition) ________ (adults only, 90% of composition) _______ (adults only, ~ 50% of composition) _________ – not mineralized in most vertebrates, sharks major exception _________—primitive verte. & today’s fishes __________—bonelike, mostly found only in mammals (fastens teeth to sockets)