Animals gestate and are born in one of three ways -- in a live birth (viviparity), from an egg laid outside its mother's body (oviparity), and from an egg that hatches inside its mother's body (ovoviviparity).
Viviparous animals are those whose embryos develop in their mother's body, where they receive nutrition directly from the parent (usually through a placenta), and who thus give birth to live young. This group of animals include most mammals, as well as a few reptiles and fish (such as the hammerhead shark and the shingleback skink), and most scorpions.
Oviparous animals lay eggs. Each egg contains an embryo, which develop outside the mother's body. This group of animals include birds; most reptiles, fish and amphibians; most arachnids and insects; some molluscs; and monotremes, such as the platypus.
Ovoviviparous animals combine aspects of the two. Their young develop within eggs (from which they get their nourishment), but the eggs are retained in the mother's body. The eggs hatch either at the time of birth (giving the appearance of a live birth) or shortly before or after. Animals that fall into this group include certain fish (such as sand tiger sharks and manta rays), a few amphibians (such as the Surinam toad), some reptiles (such as vipers and garter snakes), and many invertebrates.
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Answer:
Animals gestate and are born in one of three ways -- in a live birth (viviparity), from an egg laid outside its mother's body (oviparity), and from an egg that hatches inside its mother's body (ovoviviparity).
Viviparous animals are those whose embryos develop in their mother's body, where they receive nutrition directly from the parent (usually through a placenta), and who thus give birth to live young. This group of animals include most mammals, as well as a few reptiles and fish (such as the hammerhead shark and the shingleback skink), and most scorpions.
Oviparous animals lay eggs. Each egg contains an embryo, which develop outside the mother's body. This group of animals include birds; most reptiles, fish and amphibians; most arachnids and insects; some molluscs; and monotremes, such as the platypus.
Ovoviviparous animals combine aspects of the two. Their young develop within eggs (from which they get their nourishment), but the eggs are retained in the mother's body. The eggs hatch either at the time of birth (giving the appearance of a live birth) or shortly before or after. Animals that fall into this group include certain fish (such as sand tiger sharks and manta rays), a few amphibians (such as the Surinam toad), some reptiles (such as vipers and garter snakes), and many invertebrates.
Check out some related Science NetLinks resources:
An Egg Is Quiet (K-2)
Hatching Chickens (K-2)
Taking Care of a Baby (K-2)
Big Egg Mystery (3-5)
What Happens in the First Nine Months? (6-8)
Air Pollution & Pregnancy (6-12)
Born for Strokes (6-12)
Fatherly Fish (6-12)
Healthy Babies: The Science Inside (6-12)
Platypus Genome (6-12)
From Cell To DNA (9-12)
Explanation:
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