What animal group is a Platypus?

[Flibert]

I've wanted to know this because I always thought it was a mammal, but then my friend Micheal said it wasn't because it lays eggs, Can anyone help me?

[garner]

The duck/billed platypus belongs to a group called monotreme which include the echidnas they are mammals you are correct,for all they lay eggs.

[teddybon]

they also suckle their young and have fur/hair.

[dove]

I believe that from my school years (hundreds of years ago)
that a platypus suckles thier young, so I would say that a platypus is a mammal.

[wildwood]

To put the above together. The platypus and echidna are a branch of the mammals called monotremes - which means 'single ending', refering the the single opening for defecating and sexual reproduction, called a cloaca in english. All birds also have a cloaca. For reproduction the cloacas are pressed together and sperm is thus transfered.

Both lay eggs but the platypus incubates the eggs with its body warmth whereas the echidna has a primitive pouch like a marsupial (kangaroo etc).
Feeding the young is also an unusual affair. They have no nipples as such, the milk just oozes from modified sweat glands and the young just lap/suck it up from the fur.
The platypus is also the only mammal to produce venom with can be injected in enemies via a spur grown on the back legs of the male. A human can become very ill from the venom but it is not fatal.
Monotremes are a very interesting branch of the mammals.