An oviparous animal is an animal that produces eggs that later hatch to produce the young ones after being propelled out of the body of the female.
- Oviparity is the property of these animals where the fertilization may be external or internal, but the young ones are always hatched out of the body.
- Oviparous animals include most fishes, amphibians, reptiles, and even birds. Some invertebrates like insects are also oviparous.
- Ovoviviparous is another group where the eggs hatch inside the body of the animals, and the young ones come out. This is common in some snakes, sharks, and other animals.
- Oviparity has been an evolutionary strategy in many animals where some produce many small and fragile eggs while others produce few but strong and large eggs.
- Thus, the production of many eggs increases their chances of survival and thus works as a strategy for reproductive fitness.
- Some animals like frogs might undergo external fertilization where the female first lays the eggs, and the male comes to spread its sperm to fertilize the egg. The fertilized egg then develops until a tadpole hatches out of it.
- However, in other animals like hen, the male inseminates the female, resulting in internal fertilization. The female then lays and looks after the fertilized egg hatches into a chick.
- The eggs of oviparous animals are covered with hard or soft shells, depending on the animals. The size of the eggs is also characteristic of the animal.
- After laying the eggs, some animals sit on the eggs to keep them warm while others bury the eggs in the sand.
- In reptiles, the temperature of the egg is critical during embryonic development as it determines the sex of the offspring.
- Oviparous animals usually produce eggs at a particular time of the year depending on the availability of food as they provide nutrients to the egg through the yolk sac.
- Chickens lay eggs that might or might not be fertilized. In the case of the unfertilized egg, the egg doesn’t hatch to produce a young one but instead is taken by humans as a source of the nutrient.
- Examples of oviparous animals include frogs, snakes, lizards, hens, duck, fishes, shark, penguins, butterflies, octopus, etc.
A viviparous animal is an animal that develops an embryo inside the body of the female, resulting in the live birth of a young one.
- The embryo develops in special organs within the body of the female where the mother provides necessary nutrients to the embryo.
- Viviparous animals are present in all groups of vertebrates except birds. Fish, amphibians, reptiles, and mammals all have members that are viviparous even though none of the groups is exclusively viviparous.
- It has been assumed that viviparity developed from oviparity where the egg stayed inside the female for longer, causing it to hatch into a young one.
- Nutrition in different viviparous animals differs as some primitive animals have a yolk sac that provides nutrients to the embryo. In contrast, in others, the embryo develops into larvae inside the mother feeding on secretions from the reproductive parts of the mother.
- In mammals, however, the mother provides nutrients to the newborn via the secretions of the mammary glands.
- Viviparous animals reproduce sexually via internal fertilization as the embryo develops inside the body of the mother.
- Viviparous animals are also advanced in that they can carry the developing young ones with the mother from areas with many predators.
- Similarly, viviparous animals can also reproduce any time of the year as they can feed the embryo with the fat reserves in the body.
- However, viviparity might be very tiring for the mother as it might cause severe damage to the reproductive parts during birth.
- Parental care after birth differs in different viviparous animals where some mammals like humans look after the young ones while some salamanders show no parental care at all.
- In some cases, complications during childbirth might even risk the life of the mother.
- Examples of viviparous animals include humans, bears, giraffes, cattle, some sharks, salamanders, some frogs, etc.
Key Differences (Oviparous vs Viviparous)
Basis for Comparison
|Definition||An oviparous animal is an animal that produces eggs that later hatch to produce the young ones after being propelled out of the body of the female.||A viviparous animal is an animal that develops an embryo inside the body of the female, resulting in the live birth of a young one.|
|Mode of reproduction||Oviparous animals lay eggs that later hatch to form young ones.||Viviparous animals give direct birth to young ones.|
|Fertilization||Oviparous animals might undergo internal or external fertilization.||Viviparous animals reproduce exclusively by internal fertilization.|
|Development of zygote||The development of a zygote occurs outside the body of the mother.||The development of a zygote occurs within the body of the mother.|
|Nutrients||The embryo receives nutrients via the egg yolk.||The embryo receives nutrients from the mother through the placenta or similar structures.|
|Chance of survival||The chance of survival of the young ones is comparatively less as the eggs are laid in the environment where they are prone to various dangers.||The chance of survival of the young ones is comparatively more as they are protected inside the body of the mother with a sufficient supply of nutrients.|
|Hard covering||The eggs produced by oviparous animals are covered with hard shells to provide protection to the developing embryo.||The embryo is inside the body of the mother and is not covered with any hard covering.|
|Danger to the mother||Because there is no direct childbirth, the mother is not at risk.||The mother might be at risk during childbearing or childbirth.|
|Reproduction||Reproduction in oviparous animals usually occurs at a time where there is sufficient food available for the embryo.||Viviparous might reproduce at any time of the year as they provide nutrients through the reserve fat.|
|Parental care||Oviparous animals look after their eggs after laying them.||Some viviparous animals show parental care after birth, while others don’t.|
|Examples||Examples of oviparous animals include frogs, snakes, lizards, hens, duck, fishes, shark, penguins, butterflies, octopus, etc.||Examples of viviparous animals include humans, bears, giraffes, cattle, some sharks, salamanders, some frogs, etc.|
Examples of oviparous animals
- Birds are exclusively oviparous animals as all birds lay eggs as a form of reproduction.
- Chicken is among the most recognizable oviparous animals that lay hard-shelled eggs containing an embryo sac.
- Most birds fertilize internally and thus lay fertilized eggs that later develop to form the young one. However, some birds might also lay unfertilized eggs.
- Birds lay eggs in their nest and look after the eggs until they hatch, some birds like hen and ducks might even sit on the eggs to keep them warm.
- Many of the young birds are precocial, meaning they are able to walk and feed immediately upon hatching.
- However, some birds look after their young ones for some time after hatching by providing food and protection.
- Reptiles are similar to birds in the method of developing their young ones.
- Reptilian eggs, however, are soft and often leathery to touch. The shell is usually thin and colorful.
- Fertilization may be internal or external depending on the species.
- They lay eggs on land and mostly bury the eggs in the sand to provide warmth.
- The temperature during the development of the embryo is critical in the case of reptiles as it determines the sex of the young ones.
- Thus, most reptiles try to keep the eggs at a stable temperature over a long period of time.
- The size, texture, and color of the eggs in reptiles is also dependent on the species.
- Parental care after hatching is seen in most reptiles where they teach the young ones to look for food and to protect themselves.
Examples of viviparous
- Humans are viviparous animals that reproduce exclusively via internal fertilization like all other mammals.
- The fertilization takes place in the fallopian tube after which, the zygote moves towards the uterus and plants itself.
- The uterine wall is connected to the mother via the placenta that provides nutrients to the growing fetus.
- Unlike some viviparous animals, the newborn in the case of humans is completely developed before birth.
- After birth, the mother provides nourishment through the secretion of the mammary glands.
- Similarly, a high level of parental care is observed after birth, where they look after the newborn for several years.
- Higher sharks are a group of animals that are viviparous, unlike other fishes.
- Different sharks show different mechanisms of reproduction with some resembling that in the case of mammals.
- Some sharks like the Great White Shark have tissue extension from the oviducts of the female that connect to the gills of the developing shark. This structure has functional similarity to the placenta in mammals.
- Some tissues might even secrete a milky substance that allows the exchange of oxygen and nutrients with the developing embryo.
- After sufficient development inside the mother, the baby shark comes out of the cloaca. After birth, sharks exhibit very little parental care as the newborn are developed enough to look for prey.
References and Sources
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