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Modern Monotreme Forms


The following table gives details on the two remaining families of monotremes

 

 Family

 No. of Species

 Photo

 Description

 Notes

 Ornithorynchidae

 1

 

A diving modern day platypus, the only remaining species of the Family
  • Small
  • Nocturnal and semi-aquatic
  • Carnivore
  • Endemic to Eastern Australia
  • duck-billed
  • Venomous spurs on hind legs of male
  • Metabolic rate extremely low compared to other mammals (body temperatye 32C rather than the typical placental temperature of 38C)
  • Broad flat tail - a large rubbery snout
  • Body and tail coverd in brown fur
  • Webbed feet
  • 1-2kg
  • 30-40cm
  • Males a third lager than females
  • Adults are toothless
  • Reptile-like gait - legs are on the side of the body as opposed to underneath, as in most mammals
  • Can sense prey using electromagnetic sensors in the bill
  • Unique reproduction
  • Only one species remains
  • Very poorly understood for many years
  • Being monotremes, they are survors of a very early branching of the mammalian tree, a later branching is thought to have lead to the marsupial and placental groups
  • Ancestors may once have occupied part of South America (fossiled molar of ancestor found)
  • 10 sex chromosomes (most mammals have 2!)

 Tachyglossidae

 2

 

A AA Short-beaked echidna, one of two remaining species
  • Rememble hedgehogs as all are covered in coarse hair and spines
  • 30cm in length
  • Snouts are elongated and slender
  • Short limbs, strong limbs and large claws which makes tham a good digger
  • Small mouth and a toothless jaw
  • Feed by tearing open soft logs and anthills and use a long sticky tongue to catch the invertebrates that are then crushed between the toungue and the roof of the mouth
  • Acute sight
  • Protect themselves by rolling into a ball
  • Unique reproduction
  • Also known as 'spiny anteaters'
  • Only two species remain, however, they used to be much more diverse
  • Sparsely distributed and nowhere common - now considered a vunerable species

Images used, with permission, from Wikipedia



Author: Catrin Roberts
Last updated: 23.11.83
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