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Monotremes (/ ˈ m ɒ n ə t r iː m z /) are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. 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 ...
The class Mammalia is divided into two subclasses based on reproductive techniques: egg-laying mammals (yinotherians or monotremes - see also Australosphenida), and mammals which give live birth . The latter subclass is divided into two infraclasses: pouched mammals ( metatherians or marsupials ), and placental mammals ( eutherians , for which ...
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...
Cloaca of a red-tailed hawk. A cloaca (/ k l oʊ ˈ eɪ k ə / ⓘ kloh-AY-kə), pl.: cloacae (/ k l oʊ ˈ eɪ s i / kloh-AY-see or / k l oʊ ˈ eɪ k i / kloh-AY-kee), or vent, is the rear orifice that serves as the only opening for the digestive (), reproductive, and urinary tracts (if present) of many vertebrate animals.
Monotremes, only five species of which exist, all from Australia and New Guinea, are mammals that lay eggs. They have one opening for excretion and reproduction called the cloaca . They hold the eggs internally for several weeks, providing nutrients, and then lay them and cover them like birds .
Because of the early divergence from the therian mammals and the low numbers of extant monotreme species, the platypus is a frequent subject of research in evolutionary biology. In 2004, researchers at the Australian National University discovered the platypus has ten sex chromosomes , compared with two (XY) in most other mammals.
WNBA star Brittney Griner pulled out of speaking engagement earlier this week after finding a piece of tape in her hotel room with the words “Gay Baby Jail” written on it.
Among mammals, the monotremes are oviparous. Ovo-viviparity: or oviparity with retention of zygotes in either the female's or in the male's body, but there are no trophic interactions between zygote and parents. [1] This mode is found in the slowworm, Anguis fragilis. In the sea horse, zygotes are retained in the male's ventral "marsupium".