Monotremata

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Traits

  1. monotreme reproductive biology is discussed on pp. 160-161, 168-169.
    1. oviparous
    2. short gestation
    3. egg tooth 
    4. extended lactation
  2. mammae lack nipples
  3. cloaca
    1. female urogenital system [Figs. 9.8A, 9.18, 10.1A]
    2. male urogenital system
  4. abdominal testes (no scrotum)
  5. cervical ribs
  6. uncoiled cochlea
  7. shoulder girdle with precoracoids, coracoids, and interclavicle [Fig. 10.2]
  8. epipubic bones in both sexes
  9. sprawling forelimb posture
    1. fossorial
  10. rhinarium covered with electroreceptors
  11. reduced to absent dentition in extant monotremes
  12. homeothermic, but Tbody = 32° C
  13. males bear horny spurs on ankles
  14. fossil record includes the early Cretaceous of Australia and Paleocene of Argentina
Family Tachyglossidae
echidnas, spiny anteaters (Fig. 10.6)
  1. no teeth
  2. protrusible tongue
  3. powerful diggers
  4. feed on termites, insects, worms
  5. Tachyglossus-Australia & Tasmania
  6. Zaglossus--New Guinea

 

Family Ornithorhynchidae
duck-billed platypus (Fig. 10.4)
  1. platypus physiology  
  2. young with teeth, adults without teeth
  3. flattened leathery bill, with excellent tactile sense
  4. feeds on aquatic invertebrates
  5. Other aquatic adaptations
    1. webbed feet
    2. dense pelage
    3. pinnae absent
  6. venom gland in males [Fig. 10.5]
  7. nesting burrows
  8. Australia, Tasmania

 

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