14. Mammals Flashcards
Monotremata
5 species, including the platypus and the beaked echidna.
Mono, because they have one hole, the cloaca. Hear goes everything through, both reproduction and shitting. The same thing we see with reptiles.
Monotremata special characteristics
It lays eggs, wtf. Young “puggles” are born underdeveloped, but they grow quickly feeding on the mother’s milk.
The milk comes not from nipples, but from special patches on the mother’s body, which the puggle licks. Like sweat.
They don´t have teeth, because their electrolocation works better without them. They use their beak to produce electrolocation.
Spurs on male limbs contain venom and are used to fight and defence.
5 pairs of sex chromosomes including one X chromosome, which can be compared to a chromosome in birds. So in some ways, the Monotremata is reptile-like.
Lower bone in the jaw and 3 middle-ear bones.
Marsupialia (clade Metatheria)
Back in the days when all land was connected the marsupials migrated to South America and Asia from north America and Europe. In the old region, they became extinct, and first, now the marsupials are remigrating back to North America.
There have been a parallel evolution of marsupials mammals in Australia and placental mammals elsewhere.
Back in the days there where placental mammals to compeete with the marcupials mammals in Australia.
Marsupials characteristic
Most marsupials have a split penis and the female have THREE holes.
Young marsupials are born really early. The advantage is that there is no danger of failure in bad seasons, no need to protect them young against the mother’s immune system.
The placenta forms in different places for marsupials, whereas placental mammals only have one.
They don´t need the placental for that long for marsupials, because the young are born really early.
They have FOUR molars
The pouch
Marsupium means pouch
The pouch is like a placental mammals stomach in some way.
Two youngs can drink milk at the same time, but the milk will be different to meet the joyes needs. Fx fosfor is needed to make hair.
