Morphology Of Mammals


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Morphology Of Mammals

  1. 1. Morphology of Mammals By : Geonyzl L. Alviola
  2. 2. What is a MAMMAL ? <ul><li>whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands , hair , three middle ear bones used in hearing , and a neocortex region in the brain. </li></ul>
  3. 3. <ul><li>Mammals are divided into three main categories depending how they are born . </li></ul><ul><li>1. monotremes </li></ul><ul><li>2. marsupials </li></ul><ul><li>3. placentals </li></ul>
  4. 4. Monotremes <ul><li>most primitive mammals </li></ul><ul><li>mammals lay eggs; after the babies hatch, the mothers nourish their young with milk (Except for platypus) </li></ul><ul><li>name monotreme means &quot;one-holed,&quot; referring to the cloaca , a single hole that serves the urinary tract, anus, and reproductive tract in monotremes. </li></ul>
  5. 5. platypus
  6. 6. spiny anteater
  7. 7. Placental mammals <ul><li>Placental mammals are characterized by the following: </li></ul><ul><li>Brain capacity is increased, allowing more capacity for memory, learning, and conscious thought. </li></ul><ul><li>Milk-secreting glands </li></ul><ul><li>Mammals show behavioral flexibility, the ability to expand on the basics with novel forms of behavior . </li></ul>
  8. 8. <ul><li>Hair covers at least part of the body (whales are an exception). </li></ul><ul><li>Dentition (incisors, canines, premolars, and molars) is extensive and specialized to meet dietary habits. </li></ul><ul><li>Placental mammals nourish their young within the mother's uterus by the placenta that is a composite of maternal and fetal tissue. </li></ul>
  9. 9. Examples of Placental Mammals
  10. 10. Marsupials <ul><li>morphological feature which sets the marsupials apart from other mammalian groups is the marsupium, or pouch. </li></ul><ul><li>Females have 3 vaginae and 2 uteri but only a single opening - the cloaca </li></ul><ul><li>Most males have a 2 pronged penis just for the passage of sperm, and the cloaca for all waste excretion. </li></ul>
  11. 11. <ul><li>Metabolic rates. Metabolic rates in marsupials are also significantly lower than other mammals of similar sizes, and life-spans are often shorter. </li></ul>
  12. 12. Feeding Habits <ul><li>Animals were also divided according to its feeding habits. </li></ul><ul><li>1. carnivorous </li></ul><ul><li>it also include the insectivores </li></ul><ul><li>2. Omnivores </li></ul><ul><li>that eats both plants and animals </li></ul><ul><li>3. Herbivores (but they are several types of herbivory </li></ul>
  13. 13. Types of herbivores <ul><li>Granivory &quot;seed eating“ </li></ul><ul><li>Folivory &quot;leaf eating&quot;, </li></ul><ul><li>Frugivory &quot;fruit eating&quot;, </li></ul><ul><li>Nectivory &quot;nectar eating&quot;, </li></ul><ul><li>Gumivory &quot;gum eating&quot;, </li></ul><ul><li>Mycophagy &quot;fungus eating&quot; </li></ul>
  14. 14. Examples of seed eating mammals deer squirrels
  15. 15. Folivory &quot;leaf eating&quot;, Three-toed-sloth ( Bradypus variegatus ) Lake Gatun, Republic of Panama .
  16. 16. Frugivory
  17. 17. Types of Gait <ul><li>Gait is the pattern of movement of the limbs of terrestrial animals, including humans , during locomotion. Most animals use a variety of gaits, selecting gait based on speed , terrain , the need to maneuver , and energetic efficiency. </li></ul><ul><li>Gaits are generally classed as &quot;symmetrical &quot; and &quot;asymmetrical &quot; based on limb movement. </li></ul>
  18. 18. <ul><li>In a symmetrical gait , the left and right limbs of a pair alternate, </li></ul><ul><li>while in an asymmetrical gait , the limbs move together. </li></ul>
  19. 20. Other types of Gait <ul><li>Graviportal – adapted to support great body weight </li></ul><ul><li>ex. elephants </li></ul>
  20. 21. Hippopotamus Rhinoceros
  21. 22. Cursorial or Running <ul><li>- slender, long </li></ul><ul><li>limbs, legs </li></ul><ul><li>under body </li></ul><ul><li>- example </li></ul><ul><li>deer, horse </li></ul>
  22. 23. Cursorial or Running spinal flexion and extension adds length and velocity
  23. 24. Aerial For flying mammals
  24. 25. Volant <ul><li>For gliding </li></ul>
  25. 26. Tensorial or Digging <ul><li>* digging elements: teeth, feet, claws, head, snout </li></ul><ul><li>• moles, horned lizard, gr. </li></ul><ul><li>squirrel </li></ul>
  26. 27. Saltation or hopping <ul><li>thrust: </li></ul><ul><li>lengthened </li></ul><ul><li>hindlimbs </li></ul><ul><li>tail-counterbalance </li></ul><ul><li>• kangaroos, </li></ul><ul><li>some rodents, </li></ul><ul><li>rabbits, </li></ul>
  27. 28. Brachiation or arm swinging <ul><li>elongate hands </li></ul><ul><li>forming hooks </li></ul><ul><li>• fingers curved </li></ul>
  28. 29. Scansorial or climbing <ul><li>grasping & hooking </li></ul><ul><li>elements- recurved claws, nails, </li></ul><ul><li>adhesion pads, </li></ul><ul><li>prehensile tail </li></ul><ul><li>• monkeys, sloth, </li></ul><ul><li>tree squirrels </li></ul>
  29. 30. Swimming and diving <ul><li>streamlined body, limbs </li></ul><ul><li>modified into flippers (seals), </li></ul><ul><li>cetaceans & manatees & </li></ul><ul><li>dugongs (sirenians) lost </li></ul><ul><li>hindlimbs horizontal tail </li></ul><ul><li>flukes </li></ul>
  30. 31. Swimming and diving
  31. 32.   Kinds of teeth <ul><li>only mammals have differentiated ( heterodont ) teeth </li></ul><ul><ul><li>incisors -anterior-most teeth [uppers occur on premaxilla] </li></ul></ul><ul><ul><li>canines --longer, conical teeth used for grasping </li></ul></ul><ul><ul><li>cheek teeth --post canine </li></ul></ul><ul><ul><ul><li>premolars --cheekteeth that have deciduous predecessors (milk dentition) </li></ul></ul></ul><ul><ul><ul><ul><li>molariform teeth, squarish teeth used for grinding food </li></ul></ul></ul></ul><ul><ul><ul><li>molars --cheekteeth that do not have deciduous predecessors </li></ul></ul></ul><ul><li>NOTE that some mammals have homodont dentitions. </li></ul><ul><li>edentulous (edentate - without permanent teeth) </li></ul>
  32. 33. <ul><li>A typical mammalian tooth is made up of three regions: the crown, the neck and the root </li></ul><ul><li>The visible part of the tooth that emerges from the gum is the crown; the neck of the tooth is surrounded by the gum. </li></ul>
  33. 34. <ul><li>The tooth is anchored in the gum by the root, and a layer of bone-like tissue, called cement, fixes the root to the jaw bone. </li></ul><ul><li>In most mammals, the permanent teeth eventually stop growing and their blood supply is reduced, at which point the teeth are described as ‘rooted’. </li></ul>
  34. 35. <ul><li>Types of teeth based on function: </li></ul><ul><li>1. incisors – used for cutting </li></ul><ul><li>- located in front </li></ul><ul><li>2. canine – spike-like teeth with single </li></ul><ul><li>root </li></ul><ul><li>- used for holding and </li></ul><ul><li>piercing </li></ul><ul><li>3. premolar – located behind the canine </li></ul><ul><li>used for grinding </li></ul><ul><li>4. molar - larger than premolar </li></ul>
  35. 36. Humans
  36. 37. Dentition <ul><li>The development of teeth and its arrangement in the mouth </li></ul><ul><li>Classification of dentition would be based on the : </li></ul><ul><ul><li>- arrangement - shape </li></ul></ul><ul><ul><li>- attachment - composition </li></ul></ul><ul><ul><li>- function </li></ul></ul>
  37. 38. Replacement <ul><li>typically mammals are diphyodont - -have a single deciduous milk dentition </li></ul><ul><li>some are polyphyodont --have multiple replacement sets (Trichechidae-30+ molars) </li></ul><ul><li>toothed whales are monophyodont --have only a single set </li></ul><ul><li>Most tooth replacement is vertical. </li></ul><ul><li>Trichechids and Elephantidae have horizontal tooth replacement </li></ul>
  38. 40. Types of teeth as to Attachment <ul><li>1. Acrodont – rootless teeth </li></ul>Attached to the rim of the jawbone e.g. lizards, tuatara
  39. 41. <ul><li>2. Pleurodont – rootless teeth, </li></ul><ul><li>- attached to lingual side of </li></ul><ul><li>jaw </li></ul><ul><li>e.g. Lizards, snakes </li></ul>
  40. 42. <ul><li>3. Thecodont – having teeth rooted in </li></ul><ul><li>sockets </li></ul><ul><li>e.g. mammals </li></ul><ul><li>crocodilians </li></ul>
  41. 43. Types of teeth as to size/shape of crown <ul><li>1. Brachydont – crowns are low </li></ul>e.g. humans pigs
  42. 44. <ul><li>2. Hypsodont – crowns are high </li></ul><ul><li>e.g. horses </li></ul>
  43. 45. <ul><li>3. Bunodont – crowns form peaks (omnivores) </li></ul>
  44. 46. <ul><li>4. Lophodont – cusps drawn out into ridges </li></ul><ul><li>e.g. rodents </li></ul>
  45. 47. <ul><li>5. Selenodont – cresent-shape cusps </li></ul>
  46. 48. Dental Formula <ul><li>All mammal species have a fixed arrangement of teeth which can be generalized into a dental formula. </li></ul><ul><li>The jaws of a mammal are vertically symmetrical. </li></ul>
  47. 50. Varieties of Premolars and Molars Insectivores eat insects. Many insects have a hard exoskeleton to protect their soft inner bodies. In order to pierce this hard body armour, insectivores of disinctive points on their molars. hedghog (Erinaceus europaeus) cheek teeth
  48. 51. Herbivores <ul><li>Mostly are vegetarian </li></ul><ul><li>These animals are ruminants. (these are animals who are not equip a cellulase to digest the cellulose </li></ul>sheep (Ovis aries) cheek teeth
  49. 52. Carnivores <ul><li>There teeth are specialised to cope with holding drown prey and tearing flesh. </li></ul>
  50. 53. <ul><li>Carnivores have a special tooth in both sides of the jaw, these are called a carnassial teeth. These teeth are the last upper molar and the first lower premolar. These teeth are designed to shear through flesh. </li></ul>
  51. 54. Omnivore <ul><li>The premolars of omnivores vary in shape according to which order the animal belongs. Probably the most distinguishing feature in the Omnivore mouth are the molars. These teeth usually have more flattened crowns. </li></ul>
  52. 55. pig (Sus scrofa) molars
  53. 56. Placental Structure <ul><li>Two characteristics are particularly divergent and form bases for classification of placental types </li></ul><ul><li>1. The gross shape of the placenta and the distribution of contact sites between fetal membranes and endometrium. </li></ul><ul><li>2. The number of layers of tissue between maternal and fetal vascular systems. </li></ul>
  54. 57. Classification Based on Placental Shape and Contact Points <ul><li>Examination of placentae from different species reveals striking differences in their shape and the area of contact between fetal and maternal tissue: </li></ul><ul><li>Diffuse : Almost the entire surface of the allantochorion is involved in formation of the placenta. Seen in horses and pigs . </li></ul>
  55. 58. Classification Based on Placental Shape and Contact Points <ul><li>Cotyledonary : Multiple, discrete areas of attachment called cotyledons are formed by interaction of patches of allantochorion with endometrium. The fetal portions of this type of placenta are called cotyledons, the maternal contact sites (caruncles), and the cotyledon-caruncle complex a placentome. This type of placentation is observed in ruminants . </li></ul>
  56. 59. Classification Based on Placental Shape and Contact Points <ul><li>Zonary : The placenta takes the form of a complete or incomplete band of tissue surrounding the fetus. Seen in carnivores like dogs and cats , seals, bears, and elephants. </li></ul><ul><li>Discoid : A single placenta is formed and is discoid in shape. Seen in primates and rodents . </li></ul>
  57. 61. Classification Based on Layers Between Fetal and Maternal Blood <ul><li>Just prior to formation of the placenta, there are a total of six layers of tissue separating maternal and fetal blood. There are three layers of fetal extraembryonic membranes in the chorioallantoic placenta of all mammals, all of which are components of the mature placenta: </li></ul><ul><li>1. Endothelium lining allantoic capillaries </li></ul><ul><li>2. Connective tissue in the form of chorioallantoic mesoderm </li></ul><ul><li>3. Chorionic epithelium, the outermost layer of fetal membranes derived from trophoblast </li></ul>
  58. 62. <ul><li>There are also three layers on the maternal side, but the number of these layers which are retained - that is, not destroyed in the process of placentation - varies greatly among species. The three potential maternal layers in a placenta are: </li></ul><ul><li>1. Endothelium lining endometrial blood vessels </li></ul><ul><li>2. Connective tissue of the endometrium </li></ul><ul><li>3. Endometrial epithelial cells </li></ul>
  59. 66. <ul><li>1. Centric: the embryo expands to a large size before implantation, then remains in the center of the uterus. Examples include carnivores, ruminants, horses, and pigs. </li></ul><ul><li>2. Eccentric: The blastocyst is small and implants within the endometrium on the side of the uterus, usually opposite to the mesometrium. Examples include rats and mice. </li></ul><ul><li>3. Interstitial: The blastocyst is small and erodes through endometrial epithelium into subepithelial connective tissue. Such implantation is often called nidation (&quot;nest making&quot;). Examples include primates, including humans, and guinea pigs. </li></ul>