The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified by structural differences in their brains, jaws, digestive tract, reproductive tract, and other body parts, compared to the more common mammalian types.

2025年3月22日 · Monotreme, any member of the egg-laying mammalian order Monotremata, which includes the amphibious platypus and the terrestrial echidnas of continental Australia, the Australian island state of Tasmania, and the island of New Guinea. It is the most ancient living order of mammals.

2017年8月1日 · All of the surviving members of the monotreme group are indigenous to the island of New Guinea and Australia. Four species of echidnas and the duck-billed platypus account for the five monotreme species living in the world today.

Scientists believe that a number of monotreme species formerly walked the earth. But currently, there are only four living monotremes. These include: Western long-beaked echidna; Sir David’s long-beaked echidna; Eastern long-beaked echidna; Platypus; Many people are familiar with the last species on this list.

2024年11月18日 · Monotreme (noun, “MON-oh-treem”) Monotremes are a unique group of mammals that lay eggs. Only five species of monotreme exist today. All live in either Australia or New Guinea. The platypus (Ornithorhynchus anatinus) is one example. The other four belong to a group called echidnas, or the spiny anteaters.

2024年7月9日 · These mammals derive their name from the Greek word monotreme, which means ‘single opening.’ This term refers to the single duct or cloaca that serves as the common exit point for their urinary, defecatory, and reproductive systems.

Monotreme (monos, single + trema, hole) means "single opening" in Greek, and comes from the fact that their urinary, defecatory, and reproductive systems all open into a single duct, the cloaca. Other mammal females have separate openings for reproduction, urination, and defecation.

2023年8月16日 · A monotreme is any mammal that lays eggs. You probably know about the platypus, the most famous monotreme. But have you heard about echidnas? In addition to being the only mammals that lay eggs, these animals have a number of strange characteristics that set them apart from most other mammals alive today. Here are several fascinating facts ...

2019年6月5日 · Monotreme's Most Obvious Differences From Other Mammals . The most striking difference from other mammals is that monotremes lay eggs. Similar to other mammals, they do lactate (produce milk). But instead of having nipples like other mammals, monotremes secrete milk through mammary gland openings in the skin.

The only living monotreme species are the platypus and echidnas (see Figure below and Figure below). They are found solely in Australia and New Guinea (an island not far from Australia). This egg-laying, venomous, duck-billed, beaver-tailed, otter-footed mammal is a platypus, a monotreme mammal that reproduces by laying eggs.