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BIOL 211 - Post-Midterm Notes

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BIOL 211
Vivian Dayeh

BIOL  211  –  Introduction  to  Vertebrate  Zoology     Lecture  11:  Amphibian  Diversity  and  Adaptations     Introduction   − Extant  amphibians  fall  into  three  lineages:   o Anurans  –  frogs  and  toads  (figure  10-­‐7f)   o Urodeles  –  salamanders  (figure  10-­‐1i)   o Gymnophionans  –  caecilians,  aprodans  (figure  10-­‐10a)   − Frogs  are  the  most  successful  amphibians  in  terms  of  form,  function,  diversity  of  habitat,  and   number  of  species   − Salamanders  employ  walk-­‐trot  locomotion   o Move  forelimbs  and  hind  limbs  in  succession  to  create  sine  wave  locomotion     Amphibian  Characteristics   − Well-­‐developed  limbs   o Except  caecilians  and  some  salamanders   − Tails  present  in  salamanders  but  absent  in  frogs   − Moist,  permeable  skin  containing   mucus  glands   o Provides  cutaneous  gas  exchange   o O 2  2O  pass  from  atmosphere  to  organism   via  skin   o Have  poison  (granular)  glands   − All  adult  forms  are  carnivores   o Large  mouths/buccal  cavities   o Eat  anything  they  can  catch  and  swallow   − Papilla  amphiborum:  a  special  sensory  area  for  sound  reception  found  in  the   sacculus   within  the  inner  ear   − Operculum-­‐columella  complex:  two  bones  to  transmit  sound  in  the  inner  ear   − Frogs  and  salamanders  have  special  retinal  cells  called   green  rods   o Caecilians  lack  these  rods   o Allows  them  to  get  a  better  visual  of  the  environment   − Tympanic  membrane  picks  up  changes  that  are  t ranslated  as  sound  and  then  transported   to  the  oval  window   o Eardrum   o Found  on  surface  of  organism   o No  external  ear  associated  with  amphibians   − Oval  window  transports  sound  waves  into  the  inner  ear   − Pedicellate  teeth:  composed  of  a  dentin-­‐based  crown  and  base  (pedicel)  that  is  separated   by  extracellular  matrix  material   − Outward  bulge  of  the  eye  due  to  the   levator  bulbi  muscle   o Enlarges  the  buccal  cavity,  allowing  them  to  engulf  more  material   − Salamanders  and  caecilians  swim  by  passing  along  a  sine  wave  down  the  body   − Anurans  thrust  the  hind  legs  for  locomotion  (figure  10 -­‐5b)   o Inflexible  vertebral  column  keeps  body  like  a  rigid  bar   o Long  hind  limbs  and  webbed  toes  allow  them  to  propel  themselves  via   jumping/hopping/swimming     Salamanders   − Order  Caudata  (Urodela)   − Elongated  body  shape  with  four  functional  limbs   − Least  specialized  of  all  amphibians   − Move  with  walk-­‐trot  gait   − Many  species  found  in  Northern  Hemisphere     Salamander  Characteristics   − Paedomorphosis:  retention  of  juvenile  characteristics  in  the  adult  form   o Ex.  Mexican  Axoloti  retains  external  gills   − Can  grow  to  be  quite  large  (figure  10 -­‐1a)   o Ex.  Japan  giant  salamander  (Andrios),  hellbenders  (Cryptobranchus),  Mudpuppies   (Nectarus)   − Cave-­‐dwelling  salamanders  have  adaptations  that  aren’t  seen  in  other  terrestrial  types   (figure  10-­‐1e,  f)   o Blind,  white,  paedomorphic,  enhanced  olfaction   o Ex.  Texas  blind  salamander  (Eurycea),  European  olm  (Proteus)   − Many  salamanders  go  through  an  aquatic  larvae  stage  and  lose  gills  ing  metamorphosis o Other  than  paedomorphic  species   − Most  amphibians  hav e  simple  lungs   o Open  sacs  with  little  septa/branching   o Plethodontidae  is  a  family  of  terrestrial  salamander  that  is  lungless  and  relies  on   cutaneous  respiration  for  gas  exchange   − Many  Plethodontids  are  able  to  protrude  the  tongue  to  capture  prey  (figure  10 -­‐2)   o Bolitoglossine  plethodontids   o More  frontal  eyes  are  used  to  determine  the  distance  of  prey  r  increased  precision   Anura  (figure  10-­‐5b)   − ~5400  species   − Found  all  over  the  world,  except  Antarctica   − Have  adaptations  to  the  skeletal  system  for  jumping  (speciali zed  locomotion)   o Elongated  hind  legs  and  toes   o Fused  tibia  and  fibula   − Stiff  vertebral  column  along  with  the  pelvis  provide  a  derived  characteristic   o Little  lateral  flexibility   o Elongated  ilium   o Fused  posterior  vertebrae  form  the   urostyle   o Rigid  posterior  trunk   − Length  of  the  forelimbs  and  hind  limbs  indicate  locomotion  (figure  10 -­‐6)   o Short  fore  limbs  and  hind  limbs  =  burrowing   o Full  webbing  present  =  swimming   o Webbing  absent  =  hopping     Anuran  Diversity  (figure  10-­‐7)   − Ranidae  –  aquatic  or  terrestrial  tree  frogs   o Found  throughout  most  of  the  world   o Most  have  aquatic  tadpoles   o Powerful  hind  limbs  for  propelling  themselves  and  hopping   o Extensive  webbing  on  feet  for  swimming   o Ex.  Rana  pipiens  –  Northern  leopard  frog   − Bufonidae  –  terrestrial  frogs  that  are  true  toads   o Note:  all  toads  are  Anura  (frogs),  but  not  all  frogs  are  toads   o Parotid  glands  on  the  back  of  the  head   o Secrete  bufotoxin  when  stressed   o Ex.  Bufo  bufo   − Hylidae  –  mostly  arboreal  frogs,  but  some  are  terrestrial  or  aquatic  (figure  10 -­‐7f)   o Commonly  known  as  tree  frogs   o Adhesive  pads  on  hind  limb  and  fore  limb  digits  ( toe  discs)  to  adhere  to  smooth   surfaces     o Epidermal  layer  has  peg-­‐like  projections  with  spaces  that  contain  mucus  glands   (figure  10-­‐8)   § Forms  watery  matrix  for  attachment   § Creates  surface  tension  that  allows  toe  discs   to  stick  to  it   § Frogs  have  to  stick  to  a  surface  with  their  heads  up   o Ex.  Agalychnis  callidryas  –  red  eyed  tree  frog   − Dendrobatidae  –  toxic  terrestrial  frogs   o Poison  dart  frogs   o Brightly  coloured   o Aposematic  organism:  colourings  signal  to  predators  not  to  eat  th em   o Tadpoles  hatch  from  terrestrial  eggs  and  are  transported  to  water  by  adult   o Ex.  Dendrobates  leucomelas  –  yellow-­‐banded  poison  dart  frogs   − Rhacophoridae  –  frogs  living  in  Asia  and  Africa   o Arboreal  frogs  that  have  enlarged  toe  discs,  wide -­‐spreading  limbs,  and  extensive   webbing   o Secrete  mucus  from  glands   o Ex.  Rhacophorus  malabaricus  –  Malabar  gliding  frog   − Centrolindae  –  glass  frogs   o Translucent  abdominal  skin   o Can  see  internal  organs/viscera  on  ventral  side   o Arboreal   o Live  in  Central  and  Northern  South  America   o Adaptations  allow  attachment  to  surface   o Ex.  Cochranella  granulosa     Caecilians   − Order  Gymnophiona   − Legless,  burrowing  or  aquatic  amphibians   − Worm-­‐like  in  appearance   − Found  in  tropical  habitats   − Greatly  reduced  eyes   o Some  species  lack  eyes   o Others  have  skin  fold  coverin g  eyes   − Anuli:  dermal  folds  (figure  10-­‐10a)   o Ring-­‐like  structures  that  give  segmented  appearance   o Dermal  scales  present   − Tentacles:  specialized  sensory  organ  between  the  eye  and  nostrils   − Some  females  brood  their  eggs  (figure  10-­‐1b)   o Hold  clutch  of  eggs  and  prot ect  them  as  they’re  developing   o Others  give  birth  to  formed  young   − Embryos  of  terrestrial  species  have  filamentous  gills  (figure  10 -­‐10c)   o Help  with  aspiration   o Shed  shortly  after  hatching   − Embryos  of  aquatic  species  have  balloon/sac -­‐like  lungs  (figure  10-­‐10d)   o Temporary  structure   o Not  paedomorphic     Amphibian  Reproduction   − Range  of  mode  and  mechanisms   − Most  lay  eggs  on  water,  land,  or  carried   o Young  may  hatch  as  aquatic  larvae  or  fully  formed   o Others  retain  eggs  and  give  birth  to  metamorphosed  young   − Parental  care  varies     Caecilian  Reproduction   − Males  have  a  penis -­‐like  organ  called  a  phallodeum   o Emerges  from  the  cloaca  for  internal  fertilization  on  the  female   − Exhibit  both  oviparity  and  viviparity  (figure  10-­‐1b)   o Oviparous:  brooding  characteristic   o Viviparous:  large  young  bor n  in  small  numbers,  gill  structure  present     Salamander  Reproduction   − Most  exhibit  internal  fertilization,  though  some  use  external  fertilization   − Males  deposit  a  capsule  of  sperm  supported  by  a  gelatinous  base  called  a   spermatophore   (figure  10-­‐11)   − May  be  oviparous  or  viviparous   − Most  that  breed  in  water  lay  eggs  in  water   − Viviparous  species  are  few   o Ex.  European  alpine  salamander   o Gives  birth  to  fully  developed  young   o 2-­‐4  year  gestation   o Feed  on  yolk  sacs,  then  unfertilized  eggs,  and  then  on  maternal  reproductive  l ining     Anuran  Reproduction   − Short  season  =  explosive  breeding   o Breeding  may  only  last  a  few  days   o Transient  aquatic  habitats:  small,  temporary  pools  of  water  that  form  after  rainfall   o Males  and  females  arrive  at  the  same  time   − Longer  season  =  prolonged  breeding   o May  last  for  several  months   o Males  arrive  at  breeding  site  first   − Vocalization:  “advertisement  calls”  used  to  find  a  mate   o Very  diverse  in  pitch,  length   o Throat  sac  opens  up  as  air  is  passed  across   o Carried  over  long  distances   o Some  frogs  put  themselves  in  a  ho le  to  amplify  their  calls   o Females  respond  when  eggs  are  ready  to  be  laid   − Most  anurans  reproduce  via  external  fertilization   − Amplexus  formation:  male  grasps  female  as  part  of  the  mating  process   o “Pseudocopulation”  since  no  sperm  deposition   o Axillary  amplexus:  male  uses  forelimbs  to  grab  female  around  the  pectoral  region   o Inguinal  aplexus:  male  uses  forelimbs  to  grab  female  around  the  pelvic  region   − Some  species  have  internal  fertilization   o Lay  eggs  on  land  or  are  viviparous   − Great  diversity  in  reproductive  modes  (f igure  10-­‐16h)   − Foam  may  be  produced  during  amplexus   o Eggs  and  sperm  deposited  within  it,  eventually  gets  hard  externally,  tadpoles  drop   from  it  into  the  water  to  carry  out  aquatic  larval  stage   − Some  lay  eggs  in  bromeliads,  where  they  mature   o Bromeliad:  a  tropical  plant  that  accumulates  water,  creating  a  pool  that  Anura  use  to   rear  young   o Some  females  deposit  unfertilized  eggs  there  to  provide  nourishment  for  young   − Many  species  (both  male  and  female)  protect  their  eggs  as  they  develop  (figure  10 -­‐16e)   o Poison  dart  frogs  lay  eggs  on  the  ground,  and  transport  tadpoles  to  water  after  they   hatch   o Others  carry  eggs  with  them  until  they  are  ready  to  hatch     Amphibian  Specializations     Tadpoles   − Larval  stage  of  Anurans   − Many  species  do  not  have  this  stage,  but  for  others  it  is   a  key  developmental  stage   − Great  range  of  habitats   − Vary  greatly  in  size  and  morphology  depending  on  where  mating/egg  deposition  occurred,   and  availability  of  food   o Ovoid  bodies  and  tails  with  thick  fins  =  still  water   o Streamlined  bodies,  small  tail  fins  =  fas t-­‐flowing  water   − Variation  in  mouthparts,  depending  on  feeding  mechanism  (figure  10 -­‐17,  10-­‐18)   o Surface:  gulp  at  surface  air   o Suspension:  lie  in  watershed   o Scrapers:  bit  at  bottom  of  material,  scrape  rock   o Scraping  with  suction:  adhere  to  substance,  scrape  away  at  it   − Most  species  are  filter -­‐feeding  herbivores  as  tadpoles   o “Eating  machines”  with  a  spiral  intestinal  tract  that  allows  a  constant  wave  of   material  to  pass  into  gut   o Filter  water  as  it  passes  over  gills  (figure  10 -­‐19)   o Material  moves  to  esophagus   o Adults  are  carnivores   − Some  tadpoles  scrape  the  surface  of  materials  to  feed   o Keratinized  tooth-­‐like  processes  scrape  and  release  food  particles  into  the  water   that  is  filtered  by  the  branchial  apparatus   − Some  tadpoles  are  carnivorous  and  feed  on  other  tadpoles   o Sharp,  keratinized  beak  bites  off  flesh  that  is  then  filtered  out  of  the  water     Metamorphosis   − Tadpole  is  a  temporary  stage  in  the  life  cycle  of  Anura   − Metamorphosis  results  when  the  components  of  a  tadpole  are  broken  down  and  rebuilt   into  the  adult  frog   o Stimulated  by  the  hormone  thyroxine,  which  is  released  from  the  thyroid  gland   o Thyroid-­‐releasing  hormone  (TSH)  produced  in  the  pituitary  gland  in  the  brain   o Involves  visible  changes  in  the  entire  body   − Larval  development  is  divided  into  three  stages  (table  10 -­‐15)   o Pre-­‐metamorphosis:  tadpole  increases  in  size   o Pro-­‐metamorphosis:  appearance  of  hind  legs  and  slow  growth  of  body   o Metamorphic  climax :  emergence  of  forelegs  and  regression  of  tail     Gas  and  Water  Exchange   − Amphibian  skin  is  permeable  to  gases  and  water   o Contains  mucus  glands  that  secrete  glycopeptides  to  keep  the  skin  moist   − Adults  lose  gills  found  in  larvae  and  develop  simplistic,  sac -­‐like  lungs  for  respiration   o Few  septa  going  into  lung  chamber   − Cutaneous  respiration  allows  for  gas  exchange   o Balanced  with  pulmonary  fu nction   o Slight  distance  between  blood  vessels  and  cutaneous  layers  make  it  easily   permeable   o Able  to  survive  in  aquatic  environments  without  resurfacing  because  of  this   − Amphibians  do  not  drink  water   o Water  uptake  goes  across  skin  and  easily  permeates  into  the  amphibian   − Those  living  in  aquatic  environments  need  to  overcome  the  continuous  influx  of  water   o Produce  urine  in  copious  amounts  to  eliminate  waste  and  excess  water   o Reabsorb  water  via  kidneys  if  needed   o Carnivores  may  get  some  water  via  food   − Pelvic  patch:  a  specialized  region  found  near  the  hind  limbs  of  terrestrial  amphibians   o Highly  vascularized  skin  for  water  absorption   o Amphibian  flattens  itself  near  soil,  uses  pelvic  patch  to  pick  up  extra  water     Defense  Mechanisms  (figure  10-­‐24)   − Mucus  on  skin  makes  them   hard  for  predators  to  hold   o Salamanders  have  sticky  mucus   − Poison  glands  are  found  on  dorsal  surface  of  skin   o Range  in  toxicity;  most  are  just  irritants   − Salamanders  also  have  a  hedonic  gland  that  produces  pheromones  to  attract  mates     Lecture  14:  Adaptations  of  Synapsids  and  Sauropsids  (figure  11-­‐5)   − Amniotes  can  be  divided  into:   − Sauropsids   o Turtles,  reptilians,  crocodiles,  birds   o Extinct  sauropsids  include  dinosaurs,  pterosaurs   − Synapsids   o Mammals   o Extinct  individuals  include  pelyosaurs,  therapsids  (figure  18 -­‐3)   − Synapsids  and  sauropsids  exhibit  parallel  evolutionary  trends   o Happened  on  their  own,  seen  to  be  similar  over  time   − Differences  in  derived  basic  functions  (respiration,  locomotion,  insulation,  waste  excretion)     Locomotion  and  Respiration   − Early  non-­‐mammalian  synapsids  had  short  limbs  with  a  sprawling  posture  (out  to  sides)   − Limbs  move  underneath  with   therapsids,  but  not  as  much  as  extant  mammals   − Diaphragm  development  separated  anterior  and  posterior  body  cavities   o Creates  pulmonary  and  abdominal  cavities   o Contracts,  goes  from  dome  to  flattened  shape,  expands  pulmonary  cavity,  inhalation   occurs   o Produces  negative  pressure  for  respiration   − Bounding  gait  can  aid  in  respiration   o Movement  of  viscera  helps  force  air  out  of  lungs   o Can  also  expand  chest  cavity  and  allow  more  air  in   − Respiration  and  locomotion  work  synergistically   o Inhalation  and  exhalation  work  together  with  locomotion  in  quadrupeds   o In  humans,  bipedal  locomotion  is  detached  from  respiration   − For  ventilation,  sauropsids  use  pelvic  movements  and  ventral,  interlocking   ribs  called   gastralia  (figure  11-­‐4)   o Gastralia  are  found  in  tuatara  and  crocodilians  only   o Were  present  in  many  dinosaurs,  pterosaurs,  plesiosaurs,  early  synapsids  according   to  fossil  evidence   o Move  viscera  out  of  the  way,  open  up  region  for  ventilation     Lung  Diversity   − Ancestral  lung  was  balloon -­‐like  structure  with  limited  septa  (figure  11-­‐6a)   − Lungs  need  a  large  surface  area  for  gas  exchange  to  meet  the  demands  of  the  organism   − Synapsids  and  sauropsids  have  both  developed  complex  lungs  with  different  structures   − Synapsids  have  an  alveolar  lung  (figure  11-­‐6b)   o Tree-­‐like  dichotomous  pattern  of  branching   o Alveoli  covered  with  capillaries   − Sauropsids  have  a  faveolar  lung  (figure  11-­‐6c)   o Various  branching  patterns   o Cup-­‐like  chambers  known  as  ediculi,  faveloi,  air  capillaries     Synapsid  Lungs   − Air  travels  through  the  trachea  to  progressively  smaller  airways  via   primary  bronchi   o 23  levels  of  branching  in  humans   − Air  reaches  the  terminal  (respiratory)  bronchioles  that  contain  the   alveolar  sacs  where  gas   exchange  occurs   o O 2  travels  from  alveoli  to  blood  capillaries   o CO 2  ls  from  blood  to  alveoli   − Tidal  ventilation  brings  air  into  and  out  of  the  airways  to  the  alveoli   o Air  coming  in  via  inspiration  reaches  terminal  air  sacs  from  lungs   o Expiration  travels  back  from  the  lungs  via  the  sa me  pathway   − Alveoli  stay  inflated  due  to   surfactant  production   o Breaks  apart  cohesive  nature  of  water  lining  the  alveoli,  reducing  surface  tension     Sauropsid  Lungs   − More  variability  than  in  synapsid  lungs   o Ex.  lung  structure  found  in  lizards  is  simple  compared  to  more  complex  form  in   birds   − Air  travels  down  trachea  into  primary  bronchi   − More  surface  area  for  gas  exchange   − With  branching  to  terminal  air  sac,  gas  exchange  only  occurs  where   septa  line  the  lungs     Bird  Respiration  (figure  11-­‐7)   − More  complex  than  lizard ’s   − Unique  for  two  reasons:   − Air  capillaries  (figure  11-­‐8a)   o Small  tubules  that  radiate  from   parabronchi  for  gas  exchange   o Air  capillary  interacts  with  blood  capillaries   o Crosscurrent  exchange:  blood  travels  in  the  opposite  direction  from  air,  leading  to   more  efficient  gas  exchange   − Presence  of  air  sacs   o 9  in  total   o 2  groups:  anterior  and  posterior   o Not  used  for  gas  exchange   o Act  as  bellows  to  move  air  in  during  respiratory  cycle   − The  respiratory  cycle  includes  two  cycles  to  move  air  through  the  lungs   o Unidirectional  air  movement   − First  inspiration  (figure  11-­‐7a)   o Air  coming  in  from  environment  travels  from  trachea  and  primary  bronchi  to  the   posterior  air  sacs   o All  posterior  air  sacs  fill  up  as  bellows   o At  the  same  time,  air  currently  within  the  parabronchial  lung  moves  to   anterior  set   of  lungs   − First  expiration  (figure  11-­‐7b)   o Thoracic  volume  decreases   o Air  moves  from  posterior  sacs  to  parabronchial  lung,  where  gas  exchange  occurs   o Air  moves  from  anterior  sacs  to  primary  bronchi,  then  to  trachea  and  out  of  bird   − Second  inspiration  (figure  11-­‐7c)   o Air  travels  to  anterior  air  sacs   − Second  expiration  (figure  11-­‐7b)   o Air  that  was  in  anterior  air  sacs  travels  to  trachea,  and  out  of  bird     Heart  Structure   − Gas  that  is  exchanged  in  the  lungs  needs  to  travel  the  body  via  the  blood   o O 2  distributed  to  tissues   o CO 2  taken  from  tissues  and  eliminated  via  lungs   − Pressure  of  blood  as  it  travels  to  lungs  vs.  entire  body  needs  to  be  different   o Volume  of  blood  is  similar,  but  the  distance  is  different   o Need  to  protect  delicate  lung  tissue   − Two  circuits  for  blood  to  travel:  pulmonary  and  systemic  circulation   o Pulmonary  circulation:  blood  travels  from  heart  to  lungs,  gives  off  CO ,  picks  up  O   2 2 o Systemic  circulation:  oxygenated  blood  travels  from  the  heart  to  the  body   − Permanent  septum:  separates  ventricle  into  systemic  and  pulmonary  sides   o Heart  musculature  is  too  great  to  rely  on  diffusion  so   coronary  artery  serves  heart   as  an  organ   o Seen  in  mammals,  birds,  crocodilians   − Ancestral  amniotes  had  just  one  ventricle   − Amphibians  have  a  conus  arteriosus   o Spiral  region  within  the  heart  that  ensures  that  well-­‐oxygenated  blood  goes  in  the   opposite  direction  from  oxygen -­‐poor  blood   − Turtles  and  lizards  have  a   transient  septum   − In  mammals,  well-­‐oxygenated  blood  leaving  the  left  ventricle  leaves  via  the   left  systemic   artery  (figure  11-­‐10)   o Left  systemic  artery  is  often  called   aorta   − In  birds,  blood  leaving  the  left  ventricle  leaves  via  the   right  systemic  artery  (aorta)   o Left  systemic  artery  lost  in  adult  stage   − Most  sauropsids  retain  both   aortic  arches   o Left  and  right  systemic  arteries  prese nt   − Hypothetical  early  amniote  had  conus  arteriosus,  left  and  right  branching  to  systemic   arteries     Waste  Elimination  (table  11-­‐12)   − Nitrogenous  wastes  need  to  be  excreted  from  the  body  as  urine   − Ammonia  produced  is  water-­‐soluble  but  very  toxic   o Mostly  excreted  by  aquatic  non-­‐amniotes,  such  as  fish   o Produced  by  terrestrial  amniotes  but  converted  to  a  less  toxic  nitrogenous  waste   product   − Terrestrial  organisms  need  to  deal  with  eliminating  nitrogenous  waste  without  losing  much   water   o Urine  is  mostly  water   o Synapsids  produce  urea,  which  is  more  water-­‐soluble,  less  toxic,  and  can  be   concentrated  to  conserve  water   o Sauropsids  produce  uric  acid,  which  is  insoluble  and  forms  a  whitish  precipitate  as   sodium  or  potassium  urate;  high  metabolic  cost  of  production     Mammalian  Kidney  (figure  11-­‐13a,  11-­‐14a)   − Basic  functional  unit  is  the   nephron   − Glomerulus  filters  blood   o Surrounded  by  Bowman  capsule   − Proximal  convoluted  tubule  alters  filtrate  composition   − Loop  of  Henle  concentrates  urine     Sauropsid  Waste  Elimination   − Extant  sauropsids  are  uricotelic   o Eliminate  nitrogenous  wastes  as  uric  acid   o Can  eliminate  ammonia  and  urea  as  well   − Kidneys  of  lepidosaurs  lack  loop  of  Henle  (figure  11 -­‐15)   − Kidneys  of  birds  have  two  types  of  nephrons   o Short  loop  and  long  loop   − Uric  acid  forms  a  precipitate  in  th e  bladder/cloaca   o Water  is  reabsorbed  into  blood   − Many  sauropsids  reabsorb  salts  (Na,  K)  into  blood   o Extrarenal  salt  secreting  glands  are  an  extra  pathway  to  dispose  salts  with  less   water  than  urine   o Lizards  and  birds  have  nasal  salt  glands   o Sea  turtles  have  lacrimal  salt  glands     Sensory  Systems   − Synapsids  are  sensitive  to  odour  and  have  poor  vision   o Olfactory  region  has  very  sensitive  neurons   o Mammals  mark  territory  by  marking  scent  (urine  spray,  rubbing  of  anal  gland)   − Sauropsids  have  good  vision  and  poor  sense  of  smell   o Lizards  and  birds  use  bright  colours  for  mating  and  territorial  displays     Vision   − Two  types  of  photosensitive  cells  found  in  the  vertebrate  retina:  rods  and  cones   o Rods:  sensitive  to  low  light  in  a  wide  range  of  wavelengths   o Cones:  respond  to  different  wavelengths  of  light  and  provide  sharper  images  than   rods   − Fish  (teleosts),  amphibians,  and  sauropsids  use  cone  cells  to  preserve  colour   − Most  mammals  have   dichromatic  (2  pigment)  colour  vision   o Blue  and  green  wavelengths   − Anthropoid  (human-­‐like)  primates  see  three  primary  colour  wavelengths   o Short  =  blue   o Medium  =  green   o Long  =  red   − Birds  have  tetrachromatic  (4  pigment)  colour  vision   o Red,  blue,  green,  ultraviolet  sensitive   o Pecten  occuli:  cone-­‐like  structure  that  provides  nourishment  to  the  eye,  ensuring   that  it  doesn’t  need  a  lot  of  blood  vessels  in  the  retinal  structure     Taste  and  Smell   − Chemicals  are  perceived  via  sensory  receptor  cells  with  regard  to  taste  and  smell   − Taste  buds  give  rise  to  chemical  sensitivity  that  is  perceived  as  taste   o Found  in  oral  cavity  in  amniotes   o Derived  from  endoderm   − Olfactory  cells  are  found  in  the  turbinates  of  nasal  passages   o Derived  from  neural  crest  tissue   o Turbinates:  folded  regions  within  the  nasal  cavity  that  eventually  lead  to  olfactory   cells     Hearing   − The  lagena,  found  in  the  inner  ear,  is  an  ancestral  feature  of  hearing   o Called  the  cochlea  in  mammals   − Middle  ear  has  evolved  independently  in  amniotes   o Mammals  have  enclosed  middle  ear;   stapes,  incus,  malleus  bones   o Sauropsids  have  a  single  bone  ( stapes)  in  the  middle  ear     Brains  (figure  11-­‐7)   − Amniotes  have  an  enlarged  forebrain  for  higher  order  processing   − Birds  and  mammals  have  a  larger  brain  with  respect  to  body  size  than  non -­‐avian  reptiles     Lecture  16:  Turtles   − Very  recognizable  sauropsids   − Order  Testudines  (Chelonii)   − Variety  of  body  forms  that  reflect  their  habitat   o Terrestrial:  Aldabra  giant  tortoise   –  dome-­‐shaped  shell   o Aquatic:  Cantor’s  giant  soft  shell  turtle   –  flattened  shell     Extant  Turtles   − 13  families  within  2  suborders,  ~313  species   − Suborders  based  on  how  they  hide  their  heads  within  shell  for  protection     Suborder  Cryptodira   − “Hidden  neck”   − Retract  their  head  into  the  shell  via  vertical  S -­‐shaped  bend  of  the  neck,  contracting  it  under   the  spine   − Found  in  most  of  the  Northern  Hemisphere,  South  America,  Africa   o Not  found  in  Australia     Testudinidae   − Tortoises   − Terrestrial/land  dwelling   − Domed  shells  and  elephant -­‐like  feet   − Large  appendages  make  digging  easier   − Vary  in  size  from  very  small  (ex.  speckled  tortoise)  to  very  large  (Galapagos  giant  tortoise)     Trionychidae   − Soft-­‐shell  turtles   − Freshwater  turtles  that  have  flattened  bodies   − Reduced  ossification  lightens  the  animal   o Less  mineralization  within  bone   − Found  in  North  America,  Africa,  Asia   − Fast  swimmers  due  to  extensive  webbing   − Ex.  spiny  soft  shell  turtle     Cheloniidae   − Sea  turtles   − Bony  shell,  epidermal  scutes   − Scute:  highly  keratinized  coverings  on  top  of  shell   − Paddle-­‐like  forearms  for  aquatic  life   − Found  in  tropical  /  temperate  oceans     Dermochelyidae   − Leatherback  turtles   − Modified  shell   o Thousands  of  small  bones  ( bony  platelets)  embedded  in  a  leathery  skin   o Reduced  shell,  no  scutes   − Largest  extant  marine  turtle   − Widely  distributed   − Pelagic:  live  in  open  ocean   o Able  to  dive  quite  deep     Chelydridae   − Snapping  turtles   − Freshwater   − Stay  along  bottom  waiting  for  prey   − Found  in  North  and  Central  America   − Very  strong  jaws     Suborder  Pleurodira   − “Side  neck”   − Retract  their  head  into  the  shell  via  horizontal  bend  of  the  neck   − Found  only  in  Southern  Hemisphere   − Semiaquatic     Chelidae   − Aquatic  turtles  found  in  South  America,  New  Guinea,  Australia   − Long,  slender  necks   − Ex.  South  American  matamata   o Broad  head,  flat  shell,  skin  flaps  off  side  of  head  and  neck   o Difficult  to  find  in  water   o When  it  senses  prey,  it  opens  up  its  mouth  quickly  and  sucks  in  food     Pelomedusidae   − African  side-­‐necked  turtle   − Freshwater   − Ex.  African  helmeted  turtle     Podocnemididae   − Aquatic  turtles   − Found  in  Northern  South  America  and  Madagascar   − Inhabit  streams  of  flowing  water   − Ex.  Podochemis  expansa  –  Great  American  side  neck  turtle     Turtle  Structure  (figure  12-­‐2)   − Very  derived,  specialized  vertebrates   − Encased  in  bone   − Limbs  inside  the  ribs   − Beaks  instead  of  teeth     Turtle  Shell  and  Skeleton  (figure  12-­‐5b)   − Shell  is  very  distinctive   − Made  from  the  fusion  of  bones  and  ribs  to  the  carapace   − Carapace:  upper  shell   o Made  of  dermal  bone   o 8  along  dorsal  midline  (neural  series)   o Fused  to  vertebral  neural  arches   o 8  pairs  of  costal  bones  fused  to  ribs   o 11  pairs  of  peripheral  bones  give  border  to  carapace   − Plastron:  lower  shell   o 9  dermal  ossifications  in  total   o Entoplastron:  derived  from  interclavicle   o Epiplastron:  derived  from  clavicles   o Hypoplastron  and  hyoplastron  help  in  connecting  with  the  carapace;  hinge -­‐like   region   o Xiphiplastron:  scored-­‐like  process   − The  dermal  bones  are  covered  by   scutes  of  epidermal  origin  (figure  12 -­‐5a)   o 5  central,  4  lateral,  10-­‐12  marginal  scutes  cover  the  carapace   o Cervical,  vertebral,  marginal,  pleural   o 6  paired  scutes  cover  the  plastron   o Gular,  humeral,  pectoral,  abdominal,  femoral,  anal   − Many  turtles  have  a  flexible  hinge  region  in  the  shell   o Allows  for  areas  of  carapace  to  open/close   o Also  used  to  completely  hide  limbs  and  head   − There  are  modifications  of  the  shell  in  some  species   o Soft-­‐shelled  turtles  lack  peripheral  ossifications  and  epidermal  scutes   o Tend  to  bury  themselves  within  aquatic  environment  and  leave  head  out  until  prey   comes  around   o Leatherback  turtles  have  a  cartilaginous  carap ace  with  small  bones  embedded  and  a   thin  rim  of  plastral  bones  in  the  plastron   − 8  neck  and  10  trunk  vertebrae   − In  cryptodires,  the  cervical  vertebrae  have  articulations  to  allow  for  an  S -­‐shaped  bend  in  the   neck  to  bring  the  head  into  the  shell   o Retract  head  straight  back  so  it’s  completely  hidden  within  the  shell   − Exhibit  ginglymoidy  via  specialized  articulating  surfaces  in  the  vertebrae  called   ginglymi   o Hinge-­‐type  joint  that  can  articulate  within  one  plane     Turtle  Heart  (figure  12-­‐6a)   − Turtles  have  the  ability  t o  shift  blood  between  pulmonary  and  systemic  circuits   − Transient  septum  forms  when  ventricle  contracts   o Muscular  ridge  in  the  core  of  the  heart  divides  ventricle  into  two  spaces     Turtle  Respiration  (figure  12-­‐7)   − Turtles  are  not  able  to  ventilate  with  the  sam e  mechanism  as  other  basal  amniotes   o Other  basal  amniotes  move  rib  cage  to  draw  air  into  lungs   o Turtle  ribs  are  fused  to  the  shell  and  cannot  expand   − Lungs  attach  to  carapace  dorsally  and  laterally   − Ventrally  attached  to  non -­‐muscular  connective  tissue   − Muscles  of  inspiration:  serratus,  abdominal  oblique   o Contract,  increase  volume  of  visceral  cavity,  decreasing  pressure   o Pushes  viscera  downwards,  expands  lungs   o Air  flows  in  since  atmospheric  pressure  is  higher   –  air  moves  from  high  to  low   pressure   − Muscles  of  expirat ion:  transverse  abdominis,  pectoralis   o Contract,  decrease  volume  of  visceral  cavity   o Forces  viscera  upwards,  compresses  lungs   o Air  moves  out  of  body   − Not  a  passive  process   o Requires  muscle  contraction  during  both  inspiration  and  expiration   − Some  aquatic  turtles  use  the  pharynx  and  cloaca  for  gas  exchange   o Soft-­‐shelled  turtles  bring  air  into  pharynx  for   pharyngeal  respiration   o Australian  turtle  holds  cloaca  underwater,  pump  water  in,  conduct  gas  exchange  in   specialized  large  bursae  (sacs)     Turtle  Reproduction   − Turtles  are  oviparous   − Internal  fertilization   o Female’s  carapace  is  a  bit  of  a  problem,  so  males  have  a  concave  indentation  in  the   plastrom  to  deal  with  it   − Females  use  hind  limbs  to  dig  a  nest  in  sand  or  soil  to  lay  a  clutch  of  eggs   o May  also  use  leaf  matter  for  ne st   o Number  of  eggs  in  clutch  varies   o Development  of  embryo  in  40 -­‐60  days   − Eggs  may  be  considered:   o Soft-­‐shelled   § More  susceptible  to  damage   § Includes  Cheloniidae,  Dermochelyidae,  Chelydridae,  some  Pelomedusidae   o Hard-­‐shelled   § More  robust  than  soft  shells   § Includes  Chelidae,  Testudinidae,  Trionychidae   − Moisture  is  important  for  embryonic  development   o Water  needed  for  metabolism  of  yolk   − Hatchling  size  depends  on  moisture  level   o Most  nests  produce  larger  hatchlings  that  are  more  successful  at  escaping  predators   and  finding  food   o Small  hatchlings  from  drier  nests   − Turtles  widely  exhibit  temperature-­‐dependent  sex  determination   o Also  found  in  tuatara,  crocodilians,  some  lizards   O o Switch  between  two  sexes  within  a  temperature  range  of  3 -­‐4 C   o Several  hypotheses:  female  selects  nest  s ize,  selects  for  gender,  or  sex  size   dimorphism   o Type  1:  males  produced  at  high  temperatures,  females  at  low  temperatures   o Type  2:  females  at  high  temperatures,  males  at  low  temperatures   o Type  3:  females  at  both  high  and  low  temperatures,  males  at  intermediat es     Hatching  Behaviour   − Synchronized  in  the  nest  so  all  hatchlings  emerge  at  once   − Positive  feedback  cycle  from  vibrations  of  one  embryo  hatching  to  the  next   − Emerging  from  the  nest  is  an  exhaustive  process  that  takes  time   − Face  a  gauntlet  of  predators  as  they  make  their  way  to  the  sea     Lecture  17:  Tuatara,  Lizards,  and  Snakes   − Superorder  Lepidosauria  are  a  large  group  of  non-­‐avian  reptiles   − Characterized  by  scales  covering  the  skin  in  an  overlapping  fashion   o Allows  them  to  deal  with  dry,  aired  environments  withou t  losing  moisture   o Relatively  impermeable  to  water   − Outer  layer  is  shed  at  intervals   o Animal  tends  to  turn  dull/white  in  colour  before  skin  is  shed   − May  have  a  reduction  or  loss  of  limbs   o Many  are  tetrapods  with  archaic  tetrapod  locomotion   − Only  tetrapod  group  w ith  a  transverse  cloacal  slit   o Longitudinal  (across  midline)  in  others   − Can  be  divided  into  two  orders:   o Rhynchocephalia  –  tuatara  (figure  13-­‐1)   § Only  one  extant  species   o Squamata  –  lizards,  snakes  (figure  13-­‐2,  4)   § ~1900  species     Tuatara  (figure  13-­‐1)   − Family  Sphenodontidae   − Line  of  spines  on  back   − One  extant  species:  Sphenodon  punctatus   − Lizard-­‐like  in  appearance  but  have  a  more  primitive  rib  and  vertebrae  structure   − Nocturnal  animals   − Feed  on  invertebrates  and  small  vertebrates  (frogs,  lizards,  birds)   − Originally  found  on  North  and  South  islands  of  New  Zealand   o Humans  and  associated  animals  caused  their  local  extinction  ( extirpation)  on  the   mainland   o Now  only  found  on  ~30  islands  on  the  coast   − Live  in  burrows  that  are  shared  with  nesting  seabirds   o Feed  on  birds  and  arthropods  attracted  to  guano  produced  by  seabirds   o Guano:  waste  product  released  at  the  end  of  urinary/digestive  system   − Dentation  and  jaw  mechanisms  for   shearing  bite   o Two  rows  of  teeth  on  maxilla  (upper  jaw)  align  with  one  row  of  teeth  on  mandible   (lower  jaw)     Squamates   − Includes  lizards  and  snakes   − Amphisbaenian  –  legless  burrowing  lizards   − Determinate  growth   o Also  characteristic  of  birds,  mammals   o Crocodilians  and  turtles  grow  throughout  their  lives   − Lizards  generally  have  four  limbs   − Limb  reduction  is  associated  with  habitats  that  consists  of  dense  grass  or  shrubs   o Long,  slim  body  can  move  more  easily  in  these  habitats  than  short  body  with   functional  legs   − Amphisbaenians  have  lost  or  greatly  reduced  their  limbs   o Very  specialized  compared  to  other  squamates   − Those  with  extrarenal  salt  glands  have  nasal  salt  glands     Lizards   − Range  in  size   − Small  geckos  and  chameleons  to  large  monitor  lizards   − Many  different  body  forms  (figure  13 -­‐2)   o More  variation  for  terrestrial  and  semi -­‐arboreal  species   o Less  variation  for  arboreal  and  rock  dwe llers   − Found  worldwide  but  are  more  common  in  warmer  regions   o No  lizards  in  Antarctica  or  north  Arctic   o Found  in  habitats  from  swamps  to  deserts   o Commonly  arboreal     Lizard  Classification     Lacertidae  –  true  lizards   − ~300  species  found  in  Europe,  Africa,  Asia   − Terrestrial   − Primarily  insectivorous   − Autotomy:  can  truncate  and  regenerate  tails   − Ex.  western  green  lizard     Helodermatidae  –  glia  monsters   − Two  species  found  in  Southern  US  and  Mexico   − Semi-­‐arid  habitats   − Venomous   − Feed  on  rodents,  small  mammals   − Stout  body  form,  thick  tail   − Ex.  Heloderma  suspectum  suspectum     Varanidae  –  monitor  lizards   − ~70  species  found  in  Africa,  Asia,  East  Indes   − Vary  greatly  in  size   − Water-­‐impermeable  scales   − Most  are  carnivorous  but  some  are   frugifores  (fruit  as  primary  diet)   − Komodo  monitors  are  the  largest  living  lizard  species   o Active  predators/ambush  hunters   o Opportunistic;  will  eat  carrion   o Stalk  prey,  deliver  slashing  bite,  retreat   o Saliva  is  venomous,  acts  as  anticoagulant;  contains  bacteria,  other  enzymes   o Prey  experiences  decrease  in  blood  pressur e;  hemorrhage,  blood  won’t  clot,  bleeds   out     Iguanidae  –  iguanas   − Herbivorous   − Spines  on  back   − Marine  iguanas  are  the  only  extant  marine  lizards   o Very  specialized   o Dives  down  into  turbulent  ocean,  scrapes  away  at  algae  to  eat  it   o Gets  rid  of  extra  salt  through  n asal  salt  glands  by  sneezing     Chameleonidae  –  chameleons   − Most  specialized  arboreal  lizards   − Zygodactylous  toes   o Arranged  in  two  opposable  groups  on  forelimbs  and  hind  limbs   − Prehensile  tail:  wraps  around  twig  with  some  stability  if  chameleon  needs  to  stretch   and  let   go  with  forelimbs   − Specialized  tongue  used  to  capture  insects   − Eyes  able  to  move  independently   o Cone-­‐shaped  appearance   o Allow  chameleon  to  locate  prey  and  project  tongue  with  precision   o Eyes  don’t  have  to  point  in  the  same  direction     Amphisbaenians  –  legless  lizards   − Exception:  3  species  in  Bipes  genus  have  forelegs  to  help  with  soil  entry   − Distinctive  skin  contains   annuli  that  form  a  tube  for  the  body  to  move  through   o Allows  it  to  burrow  into  soil,  retreat  and  move  backwards  without  turning  around   − Single  tooth  on  upper  jaw   − Rigid  skull  structure  is  good  for  tunneling  (figure  13 -­‐3)   o Blunt,  wedge,  or  shovel  shapes   − Rudimentary  eyes   o May  be  covered  depending  on  the  species   o Don’t  often  use  vision  since  they’re  usually  burrowing  in  soil     Snake  Classification   − Vary  in  size   o Small  burrowing  species  –  ex.  Barbados  thread  snake   o Large  constrictors  –  ex.  reticulated  python   − Specialized  body  form   o Limbless   o Lost  pectoral  girdle   o Some  lost  pelvic  girdle,  others  have  rudimentary  one   o Specialized  skulls     Colubridae   − Catch-­‐all  name  for  classifying  snakes   − Large  number  of  extant  species   − Found  on  all  continents  except  Antarctica   − Lost  all  traces  of  pelvic  girdle   − Single  carotid  artery   − Kinetic  skull   − Ex.  garter  snake,  Eastern  hognose  snake     Boidae  –  boas/boa  constrictors   − Terrestrial,  semi-­‐aquatic,  arboreal   − Non-­‐venomous  and  primitive   − Vestigial  (rudimentary)  pelvic  girdle   − Rudimentary  hind  limb  spurs  used  in  mating   o Articulate  with  pelvic  girdle     Pythonidae  –  pythons   − Terrestrial  and  arboreal   − Found  in  Africa,  Asia,  Australia   − Includes  some  of  the  largest  snakes     Viperidae  –  vipers   − Hollow  fangs  inject  toxic  venom  into  prey   − Parotid  salivary  gland  contains  venom   − Other  teeth  aid  in  swallowing  prey     Squamate  Characteristics     Lizard  Foraging  and  Feeding   − Very  diverse  habitats   − Some  lizards  are  sedentary  with   very  little  movement;  others  are  very  active   − Foraging  mode  has  been  categorized  as  follows:   o Sit  and  wait:  ambush  predator   o Active:  spend  much  of  their  time  searching  for  prey   o Cruising:  intermediate  condition;  occasionally  active,  other  times  sedentary     Table  13-­‐14:  Lizard  Foraging  and  Feeding   Sit  and  Wait   Active   Large,  mobile  prey   Small,  sedentary  prey   Prey  for  widely  foraging  predators   Prey  for  sit-­‐and-­‐wait  predators   Stocky  body,  short  tail   Slim,  elongate  body;  long,  whiplike  tail   Limited  endurance   High  endurance   High  anaerobic  metabolic  capacity   High  aerobic  metabolic  capacity   High  sprint  speed   Low  sprint  speed   Large  egg  clutch  mass   Low  egg  clutch  mass     Autotomy  in  Lizards  (figure  13-­‐11)   − Defense  mechanism   − Some  lizards  are  able  to  easily  amputate  the ir  tail  if  seized  by  a  predator  (autotomy)   o Fracture  plates  between  caudal  (tail)  vertebra   o Contraction  of  sphincter  muscles  on  caudal  arteries  minimize  blood  loss   − Autotomized  tail  writhes  to   distract  predator   − Tail  will  regenerate   o Takes  time  and  energy  that   should  be  used  elsewhere  (ex.  producing  gametes)   o Without  a  tail,  a  lizard  may  be  unattractive  to  mates     Snake  Body  and  Locomotion  (figure  13-­‐4)   − Body  form  of  snakes  may  vary   o Slow  moving  constrictors  are  short  and  stout   o Arboreal  are  long  and  slender,  often  b lend  in  with  surroundings   o Vipers  have  large  heads,  stout  bodies   − Snake  locomotion  varies  with  body  form  and  what  they  are  moving  on   − Serpentine  locomotion  (figure  13-­‐5a)   o Lateral  undulation   o S-­‐shaped  bend   o Ventral  scales  push  off  of  surface  snake  is  moving  on,   lifting  parts  of  it  up;  weight   distribution   − Rectilinear  locomotion  (figure  13-­‐5b)   o Used  primarily  by  boas,  pythons,  large  vipers   o Large  size  makes  serpentine  locomotion  difficult   o Alternate  contraction/relaxation  of  ventral  muscles  propel  snake  in  straight  li ne   − Concertina  locomotion  (figure  13-­‐5c)   o Used  when  in  narrow  passages   o Contract  anterior  portion,  posterior  contracts,  straighten  up  anterior   o Waves  travel  down  snake’s  body,  moving  it  forward   − Sidewinding  locomotion  (figure  13-­‐5d)   o Used  in  desert  habitats   o S-­‐shaped  bend   o Entire  body  bends  sideways  to  move  it  upwards     Snake  Features  and  Feeding   − Forked  tongue   o Tips  move  independently   o Chemical  stimuli  are  transferred  to  the  paired   vermonasal  organs,  which  transfer   scents  to  the  brain  for  processing   − Very  flexible  skull  (figure  13-­‐7f)   o Large  amount  of  movement  (kinetic)   o At  the  front  of  the  mouth,  the  mandibles  are  connected  by  muscles  and  skin,  not  a   joint   o Jaw  tips  can  spread  when  snake  needs  to  swallow  large  prey   − Snakes  without  fangs  are  aglyphous  (figure  13-­‐10a)   o Teeth  are  all  the  same  size   − Opisthoglyphous  (figure  13-­‐10b)   o “Rear  grooved”   o Enlarged  teeth  in  rear  of  maxilla   o Smaller  teeth  in  front   − Proteroglyphous  (figure  13-­‐10d)   o “Forward  grooved”   o Hollow  fangs  located  at  front  of  maxilla   o Smaller  teeth  towards  rear   − Solenoglyphous  (figure  13-­‐10e)   o “Pipe  grooved”   o Long,  hollow  f
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