Transcript Barbules
VERTEBRATE ZOOLOGY (VZ Lecture23 – Spring 2012 Althoff - reference PJH Chapters 16-17) Birds – Part I Scissortail flycatcher Bill Horn 2000 Distinguishing Features of Birds __________: no other vertebrates have these. Unique modification of the outer skin—clear advancement over scales _______________: extremely lightweight… works in combination with feathers to accommodate flight ________: toothless and covered with a horny sheath. More lightweight than jaws made of bone _____________________: “richly provisioned” external eggs. Most elaborate reproductive cells of any animal Distinguishing Features of Birds __________________________: 6-11 times larger than those of like-sized reptiles. Helpful for processing sensory information, control of flight muscles HIGHLY DEVELOPED ________________ & ______________: communication systems very advanced (sight and sound to the n-th degree). Navigation, depending on species, accomplished by using patterns of Earth’s magnetism, celestial cues, and maybe even polarized light. ______________: adaptations permit allow metabolic demands of flight and temperature regulation Classification & Diversity of Birds Aves CLASS 29 ORDERS FAMILIES 187 GENERA SPECIES > 2,050 _________ Passeriformes (songbirds, perching birds, passerines) • Order with the most: Families 83 (next most is Charadriiformes… shorebirds…with 19) Genera1,161 (next most is Apodiformes… swifts and hummingbirds… with 128) Species______ (next most is Apodiformes… with 422) ____ of all bird species. Classification & Diversity of Birds CLASS Aves ______________ SUPERORDERS “old jaw” 2 orders, 11 families, 63 species includes flightless birds _____________ “new jaw” Paleognathae = old jaw • Tinamiformes (47 species) • Ratities (________ on their sternum) (16 species) A) Casuariiformes (emus & cassowaries) B) Rheiformes (rheas) C) Struthioniformes (ostriches) Variable Yet Uniform…. • Beaks and feet are specialized for different modes of feeding and locomotion • Morphology of intestinal tract is related to dietary habits • Wing shape reflects flight characteristics • Bird morphology is ______ uniform than that of mammals THIS UNIFORMITY IS BASICALLY A RESULT OF SPECIALIZATION OF BIRDS AS IT PERTAINS TO ___________. Focus on Feathers PJH Fig. 17-1 p436 • Feathers develop from pits or follicles in the skin • Except for a few species (ex. ratites, penguins), feathers are arranged in ________ or ________, which are separated by patches of unfeathered skin (the apteria). Total of ___ tracts dorsal view ventral view Feather composition • _____ of feather is composed of a specific type of _____________. This is a __________ that is closely related to the keratin that forms scales in lepidosaurs • ~1% consists of lipids • ~8% is H20 • Remainder: other proteins and pigments (including melanin) • Feather color produced by structural characters and pigments Main Structural Features of Vaned Feather • ________: anchor point to skin. Tubular in design. remains intact until molt • ________: extends from calamus to end of feather. Bears closely spaced side branches called _______. • _______: consists of barbs hooked together like velcro Rachis Vane Calamus Barbs to Barbules • Barbules branch from barbs….there are proximal barbules and distal barbules proximal barbule distal barbule BARBULES distal barbule distal end proximal end proximal barbule distal barbule rachis Ends of distal barbules bear hooks that insert in grooves in the proximal barbules of the adjacent barb __________ barbule _____________ barbule Body-contour feather: BASE • Different structure in some regions from a “typical” vaned feather • Near base, barbs and barbules are flexible and barbules lack hooks soft, loose, fluffy texture • Called plumulaceous or downy • Provides critical ________ __________ capability Body-contour feather: non-BASE • Portion above plumulaceous portion forms a tight surface called the VANE. • Open vs. closed pennaceous portions • This part of the feather is exposed to exterior surface of plumage • Serves as airfoil, protects downy undercoat, sheds H20, and reflects or absorbs solar radiation Body-contour feather: non-BASE • Barbules maintain the “closed” pennaceous portion of these feathers • Arranged such that any physical disruption to the vane is easily corrected by the bird’s preening behavior • “Realignment” (i.e., unruffling of feathers ) accomplished by bird drawing its slighlty separated bill over the vane 5 types of feathers • CONTOUR FEATHERS • SEMIPLUMES • DOWN FEATHERS (several kinds) • BRISTLES • FILOPLUMES contour feather filoplume semiplume bristle down feather Contour feathers • Includes typical body feathers and flight feathers • Flight feathers include a) remiges (sing. remex) wing feathers b) rectrices (sing. rectrix) tail feathers • Typically, large and stiff • Mostly pennaceous contour feathers that are modified for flight • Distal portions of outer primaries are usually abruptly tapered or notched…so that when wings are spread, there are slots or gaps at the tips reducing drag. Also allows feather tips to twist as wings are flapped Semiplumes • Intermediate in structure between contour feathers and down feathers • Combine a large rachis with entirely plumulaceous vanes • Distinguish from down feathers by the rachis being longer than the longest barb • Usually hidden beneath contour feathers • Provide ________________ • Provide “body” to help fill out contour of a bird’s body Down Feathers • Entirely plumulaceous • Rachis is shorter than the longest barb or totally absent • Provide thermal insulation • Adult down • Natal down…., present at hatching or very shortly (i.e., few days to week) usually precedes development of first contour feathers • Uropygial gland downat base of tail associated with sebaceous gland (oil to condition/waterproof feathers) Down Feathers…con’t • Powder down feathers breakdown to produce extremely fine white powder composed of granules of _________. • Shed into the general plumage, is not wettable, and therefore a form of waterproof dressing. Bristles • Stiff rachis and barbs only on the proximal portion…or none at all • Usually found around base of the bill, around the eyes, as eyelashes…. Occasionally on the head or even between toes of some species • Distal end of rachis is usually colored black or dark brown by melanin granules. The melanin adds strength as well as color • May help some species “capture” flying insects Collared nightjar - (found in Madagascar) Filoplumes • Fine, hairlike feathers with a few short barbs or barbules at the tip • Serve as _________ structures that aid in the operation of other feathers….have numerous free nerve endings in their follicle walls connect to pressure and vibrationreceptors around follicles transmit info about the position and movement of contour feathers • Thus impact _______, __________, _________ and ___________ contour feather ___________ Brown, R.E. and M.R. Fedde. 1993. Airflow sensors in the avian wing. Journal of Experimental Biology 179:13-30. [pdf posted on web page]