Mammalian Senses

1. Mammalogy(Fall 2013 Althoff - reference FDVM Chapter 8) LEC 09 Mammalian Senses

2. Senses • Well-developed compared to most all other classes (i.e., fishes, reptiles, etc.) • Key to “_____________” resource a) find prey (predators) b) find forage (prey) in form of seeds, grasses, forbs • Key to being “had” by predator including humans

3. Senses…con’t • Sight: probably ____ superior to birds, specifically when compared to raptors • Hearing: probably ____ superior to birds. (exception: echolocation) • Touch: ______ superior to birds • Smell: _____ superior to birds

4. forebrain hindbrain midbrain _____________vertebrate brain

5. embryonic vertebrate brain frog cerebrum cerebellum human goose

6. sheep bird SOURCE: Fishbeck and Sebastiani (2008) Fig. 12.3 Items to note here: 1) ________ proportion of cerebellum to cerebrum 2) ______—present (mammal) vs . absent (bird)—in the cerebrum exterior

7. Types of Sensory Receptors • _________________ (taste, smell) • _________________ (touch, hearing) • _________________ (sight) • _________________ (touch, pain)

8. Smell • Acute • Development of turbinal bones (tubinates) in nasal cavities (___________________ ________) • Well developed olfactory bulbs (bulla) in insectivores, carnivores, & rodents • Olfactory bulbs and lobes, great portion of brain • Primates have reduced nasal capacity

9. GENERALIZED MAMMAL CONDITION Olfaction maxilloturbinates • Some sensitivities up to 1 million trillion (1015) part of air • Mammals…with very highly developed olfaction…aided by presence of ________: thin bone lined with olfactory epithelium • vomeronasal organ (Jacobson’s organ) UNGULATE CONDITION vomeronasal organ

11. frontal bone cribiform plate mesethmoid frontal bone presphenoid bone nasal palatine maxillary premaxillary Cutaway view of nasal chamber of Abert’s squirrel(Sciurus aberti)

12. Smell...con’t • Smell accomplished through chemoreceptors (broad range of these): a) humans: ____ million b) dog: ____ million • Receptors detect food, predators, prey, and status of conspecifics

13. Smell...con’t • Olfactory “hairs” (dendrites) connect to olfactory receptors which connect to olfactory bulb • Receptor cells actually in ___________ ___________

15. To __________ lobe in brain olfactory epithelium “non-sensory” part olfactory cilia of olfactory cell

16. Smell...con’t • Evidence for rodents (& mammals in general likely) to detect: a) sex of conspecific b) maturity of conspecific c) _________________ heritage d) _______________ e) “social” status • Important in _________________

17. Hearing • Well developed in most species (as indicated by _____ of auditory bulla) • ___________ of vertebrate animals to have this much dependency on sense of hearing • Only class with ______________ (pinna) to funnel sound

18. Hearing...con’t • External auditory meatus--tube leading from pinna to tympanic membrane--is usually long in mammals • Middle ear is air-filled chamber that houses three ossicles (hammer anvil  stirrup) (malleus incus stapes)

20. FDVMK Fig. 8.2 p146

21. Hearing...con’t • Size of auditory bulla can reflect animals ability to pick-up low frequency (1-3 MHz) sounds • Ex: Kangaroo rat a) ___________________ b) ____________________ ____________________

22. Kangaroo rat (Dipodomys) FDVMK Fig. 18.10 p354

23. Auditory bulla is, on the average, larger in _____________________. Sound is known to be absorbed to different degrees under different temperature and humidity conditions. An enlarged bullae may _______________ for poor sound-carrying qualities of warm, dry, desert air

24. Echolocation • _____ of all mammals use _____________ orientation for sensing surroundings (bats, shrews, cetaceans) • Bats have overcome “darkness” with development of echolocation

25. Echolocation...con’t • Microchiropterans pretty much have abandoned vision in favor of echolocation • Echolocation: ultrasonic pulses are emitted by bats, pulses reflected back objects • Not confirmed until 1940’s

26. Echolocation...con’t • For bats, not only is prey detected, but communication with conspecifics is achieved • Vocalizations produced by larynx emitted through nose or mouth

28. Echolocation: INFORMATION GAINED 1 3 of target of the target 2 4 of the target of the target FDVMK Fig. 13.8 p263

29. Echolocation...con’t • Humans can hear _____ kHz (20,000 cycles per second) • Bats emit _______ kHz pulses with very _____ wavelengths...this range results in detect of prey closest to the size that a bat species can handle

30. Echolocation...con’t • Different species of bats emit different ranges of pulses--able to __________________ now by recording pulse rate & duration • ______ also, apparently, able to detect bat sounds to some degree…version of “___________________”

31. References on bat foraging & detection of different species:Adam, M.D., M.J. Lacki, and T. G. Barnes. 1994. Foraging areas and habitat use of the Virginia big-eared bat in Kentucky. J. Wildlife Management 58:462-469.Krusic, R.A., M. Yamaski, C.D. Neefus, and P.J. Pekins. 1996. Bat habitat use in White Mountain National Forest. J. Wildlife. Management 60:625-631.

32. Sight: eye proportional differences(specifically in the _______) d = dorsal side of eyeball v = ventral side (bottom) n = nasal (nose) side of eyeball t = temporal (outer side) c = cornea l = lens (shaded-tan) FDVMK Fig. 8.1 p145

33. Sight • Most mammals have well-developed ___________________ ...this is a reflective structure within the choroid that improves night vision by reflecting light back to the retina

34. Sight...con’t • Tapetum lucidum a) results in “________” b) some species can have different color of eye shine • _____ vs. ______ photoreceptors

36. Rods • Very sensitive to _____ light • Contribute to “coarse” vision --detection of movement by detecting changes in light intensity --good night-time vision • Contain molecules of ______________

37. Rods...con’t • Rhodopsin breaks down with light absorption, result is _________ changes across the rod membrane which, in turn, influence neurons. • _________ rods than cones in __________ species

38. CHOROID

39. Light rays Rod cell Cone cell Rod membrane To occipital lobe in brain

40. Cones • Stimulated by _________ light levels • Densely packed in fovea where nerve tissue is thinner • Contribute to “precise” _____________ between adjacent points in space

41. Cones...con’t • Pigments in different cone cells are sensitive to wavelengths corresponding to red, green, and blue colors • More abundant in diurnal species, but-- even for those--______ as much as birds

42. Up to present day, only three mammalian groups again developed retinas dominated by cones:A) SCIURID RODENTS, B) TUPAIAS (tree shrews) and C) (DIURNAL) PRIMATE GROUPS European Ground Squirrel Citellus citellus

43. European Ground Squirrel Citellus citellus • This stained semi-thin section shows the photoreceptor mosaic. • A fewrods are present but not well distinguishable at • this level of sectioning. In the ground squirrel retinas • (also the Alpine marmot for example) they are a small minority • (5%). Otherwise, apparently there are two types of cones. • subpopulation of larger darker staining cells are the • short wavelength sensitive(Blue or S-) cones. • Theyestablish a regular sub-mosaic of ca. 10%.(and they are apparently ________________) • B) Other cells are mostly (>80% )long wavelength sensitive or "Green" cones.

44. ___________ in types of photoreceptors …including types of cones 1 Regardless of number of cones and rods, object ____________ still can be _____________ 2

45. What some mammals might see… • http://premiumblend.net/2009/08/21/how-dogs-see-colors/ Human Dog

46. Sight...con’t For the most part, then, most mammals probably “see” black-and-white” but there is a ________ _______________ for those with well-developed sight (excludes microchiropterans, moles, shrews, etc.—who have really poor eyesight)