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[89] [77] She lays one to three (usually two) small, leathery eggs (similar to those of reptiles), about 11 mm (7 ⁄ 16 in) in diameter and slightly rounder than bird eggs. [90] The eggs develop in utero for about 28 days, with only about 10 days of external incubation (in contrast to a chicken egg, which spends about one day in tract and 21 ...
A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic material such as twigs, grass, and leaves, or may be a simple depression in the ground, or a hole in a rock ...
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, reproductive tract, and other body parts, compared to the more common mammalian types.
The egg is not retained in the body for most of the period of development of the embryo within the egg, which is the main distinction between oviparity and ovoviviparity. [1] Oviparity occurs in all birds, most reptiles, some fishes, and most arthropods. Among mammals, monotremes (four species of echidna, and the platypus) are uniquely oviparous.
Most arthropods, vertebrates (excluding live-bearing mammals), and mollusks lay eggs, although some, such as scorpions, do not. Reptile eggs, bird eggs, and monotreme eggs are laid out of water and are surrounded by a protective shell, either flexible or inflexible. Eggs laid on land or in nests are usually kept within a warm and favorable ...
Nests are made on the ground under the cover of thick vegetation, and built by making grass (or similar material) into a bowl to hold about four eggs. On average, female weka lay three creamy or pinkish eggs blotched with brown and mauve. Both sexes incubate.
Deep cup nest of the great reed-warbler. A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian blackbird, or the elaborately woven hanging nest of the Montezuma oropendola or the village weaver—that is too ...
Toucans are arboreal and typically lay two to four white eggs in their nests. They make their nests in tree hollows and holes excavated by other animals such as woodpeckers—the toucan bill has very limited use as an excavation tool. When the eggs hatch, the young emerge completely naked, without any down.