Monotreme mammals Flashcards
What is a monotreme mammal
Relates to the presence of a cloaca (one hole for excretion and reproduction
Defining characteristics of monotomes
Oviparous: lay eggs
Bony bill or beak (no teeth in adults)
“Ancient” shoulder girdle
Detect prey using electromagnetic sensors in bill/beak
No teats associated with mammary glands
Low body temperature (31-33°C)
Two monotreme mammals examples
Platypus - Ornithorhynchidae family
Echidnas - Tachyglossidae
Platypus history
Considered more primitive than echidnas (longer fossil record)
Still widespread
Semi-aquatic
Shelter and rear young in burrows dug into river banks - no pouch
Platypus anatomical characteristics
Skull:
Keratinous dental pads
Elongation of bony snout
Large foramina in skull for nerves to pass to bill
Bill:
Primary sense organ
Other sense often shut down
- Eyes and ears housed together in horizontal groove shut when foraging underwater
- Flaps of skin can seal dorsally located nostrils
Feet:
Spur - venom glands - used to poison prey
Platypus locomotion
forelimbs alternate for propulsion, tail and hindlimbs used as a rudder
Platypus reproductive anatomy
Male: internal testes and unique penis structure
Short beaked echidna
Widespread in Australia
Terrestrial
Diet: Ants and termites
- Electro- and touch receptors in skin of their beak
- Show classic adaptations to this diet (elongated rostrum forming toothless beak; extensible tongue; large front claws)
Activity: mainly crepuscular (dawn and dusk) but varies
Solitary, except during breeding season
Have pouch
Long beaked echidnas
All critically endangered
More variable in size than short-beaked echidna
Beak: longer, with marked downward curvature
Smaller, less numerous spines
Feeds on worms and insect larvae – distal tongue has spines in a deep groove forming a hook for snaring worms
Echidna: Anatomical Characteristics
Skull:
Mouth opening - small, opens ventrally, upper and lower jaw joined by ligaments that form a “tunnel” for tongue
Smaller, but more numerous foramen in skull for nerves to pass to beak
Echidna reproductive anatomy
Males: internal testes & unique penis structure
Female: Has pouch