Monotreme mammals

Question 1

What is a monotreme mammal

Answer 1

Relates to the presence of a cloaca (one hole for excretion and reproduction

Question 2

Defining characteristics of monotomes

Answer 2

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)

Question 3

Two monotreme mammals examples

Answer 3

Platypus - Ornithorhynchidae family

Echidnas - Tachyglossidae

Question 4

Platypus history

Answer 4

Considered more primitive than echidnas (longer fossil record)

Still widespread

Semi-aquatic

Shelter and rear young in burrows dug into river banks - no pouch

Question 5

Platypus anatomical characteristics

Answer 5

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

Question 6

Platypus locomotion

Answer 6

forelimbs alternate for propulsion, tail and hindlimbs used as a rudder

Question 7

Platypus reproductive anatomy

Answer 7

Male: internal testes and unique penis structure

Question 8

Short beaked echidna

Answer 8

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

Question 9

Long beaked echidnas

Answer 9

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

Question 10

Echidna: Anatomical Characteristics

Answer 10

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

Question 11

Echidna reproductive anatomy

Answer 11

Males: internal testes & unique penis structure

Female: Has pouch