What characteristic of monotremes sets them apart from other mammals?

Answer 1

Monotremes

Monotremes are one of the three forms of mammals. All mammals suckle their young, have three middle-ear bones, and have hair.

Monotremes are the only mammals that lay eggs. They also have extra bones in the shoulder girdle. Their legs have spurs at the sides. These have no function excepting for in male platypuses; in male platypuses they contain venom. Monotremes have no nipples and no corpus callosum. Their body temperature is only about 90 degrees Fahrenheit (as opposed to 95 in marsupials and 99 in placental mammals). They are toothless as adults. They are the only mammals that can electrolocate and the only mammals with full cloacas.

An example of a monotreme is the duck-billed platypus.

Written by a placental mammal...

Answer 2

• Monotremes are egg-laying mammals. This is different from all other mammals, which give live birth.
• Monotremes do not have teeth. The platypus has grinding plates, while the echidna has a long, sticky tongue, but no teeth.

Answer 3

Monotremes are egg laying mammals (Prototheria) instead of mammals which give birth to live young like marsupials (Metatheria) and placental mammals (Eutheria).

Australia has two species of monotremes: the platypus and the short-beaked echidna, and each of these has its own particular features. However, the feature that distinguishes these mammals from other mammals is the fact that they have just one external opening, the cloaca, for both waste elimination and for reproduction. The cloaca leads to the urinary, faecal and reproductive tracks, all of which join internally, and it is the orifice by which the female monotreme lays her eggs.

In addition, monotremes do not have teeth. Platypuses have grinding plates with which they crush their food. Echidnas have a long, sticky tongue for catching termites and ants, and they swallow their food whole.

Both types of monotremes are effective diggers, having long, sharp claws. They both dig burrows.

Answer 4

• Monotremes are egg laying mammals (Prototheria) while marsupials are mammals which give birth to live young (Metatheria).
• Monotremes have just one external opening, the cloaca, for both waste elimination and for reproduction. The cloaca leads to the urinary, faecal and reproductive tracks, all of which join internally, and it is the orifice by which the female monotreme lays her eggs.

  Female marsupials have two vaginas, or what are called paired lateral vaginae. These are for the purpose of transporting the sperm to the womb, but there is a midline pseudovaginal canal for actually giving birth. As well as two vaginas and two uteruses, female marsupials have two fallopian tubes and two cervixes. Most male marsupials, with the exception of the largest species, the Red Kangaroo, Eastern Grey and Western Grey Kangaroos, have a "bifurcated" or two-pronged penis to accommodate the females' two vaginas.

• Monotremes do not have teeth. Platypuses have grinding plates with which they crush their food. Echidnas have a long, sticky tongue for catching termites and ants, and they swallow their food whole. Marsupials do have teeth.
• Marsupials are mammals with pouches in which they rear their young (a very few species do not have pouches). Marsupial young are characterised by being extremely small and undeveloped at birth. At birth, they take a long, arduous journey from the birth canal, driven purely by instinct, grabbing hold of the mother marsupial's fur which she has cleaned and made easier to traverse with saliva, to reach the pouch. Upon reaching the pouch, they latch onto a teat which swells in their mouth to prevent them from being accidentally dislodged during the mother's movements. There they stay for months, to complete their development.

  Among the monotremes, the echidna does develop a flap of skin on her abdomen during breeding season, and she lays a single egg into this rudimentary pouch. The baby echidna hatches here. As soon as the echidna starts to develop its sharp spines, it is transferred to a burrow. Platypuses lay their eggs directly into a chamber at the end of a long burrow.

Answer 5

They lay eggs.

Answer 6

they lay eggs