OVIPAR animals: definition and characteristics

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The oviparous animals are all those who need a egg to finish its development embryonic but not all oviparous reproduce the same and not all their eggs are the same. In this lesson from a TEACHER we will review what it means for an animal to be viviparous and the different types of oviparous that we can find in nature. In addition, we will also review many examples of oviparous animals. In the animal kingdom you can see that there are oviparous birds but also some insects, fish, amphibians and even mammals. If you want to know more about the oviparous animals, definition and characteristics, We invite you to continue reading this lesson from a TEACHER!

Index

1. Definition of oviparous animals
2. Oviparous birds, main characteristics
3. Oviparous reptiles
4. Oviparous fish
5. Oviparous mammals

An oviparous animal is one that spawn eggs to complete any of its stages of embryonic development. The egg is a structure, which can be more or less hard, and that encompasses not only the embryo and its covers but also the yolk, a reserve substance that will be responsible for nourishing the embryo during its development, until it is able to hatch and go out into the world Exterior.

The main function of the egg Its the protect the embryo in development either from possible predators, from the cold, from the low humidity that would make their body dry out or simply from the blows.

Types of oviparous animals

Within this type of animals we can find two varieties of oviparous animals:

• Oviparous with external fertilization. Animals that present eggs that are fertilized in thefemale exterior they are said to be oviparous with external fertilization. In these cases, the eggs lack hard outer covers, which would prevent fertilization. Therefore, they are eggs soft. This type of reproduction, with soft eggs, can only occur in aquatic or very humid environments, since if not all the membranes that make up the egg, the nutritive reserve material (yolk) and the embryo itself they would dry out. Remember that the embryo does not yet have body covers to protect it from cold or desiccation. This type of reproduction is called ovuliparity and the animals that present it are ovuliparous animals or living beings. The best known examples of ovuliparous are fish and amphibians.
• Oviparous with internal fertilization. In other cases, the eggs are fertilized while the ovum is inside the female. In these cases we speak of an internal fertilization of oviparous animals. In this case, the males have to be in charge of introducing the sperm into the female's urogenital system. Since in this case fertilization takes place before going outside, these eggs develop a series of protective covers, made up mostly of calcium, which make them harder and resistant. We are before oviparous animals of dried eggs since the covers of it protect it from the environmental dryness. Examples of oviparous animals with dried eggs are birds or reptiles, which lay their eggs on land or in nests, but always in environments with low humidity.

The techniques, mechanisms and behaviors that different species exhibit when laying or caring for their eggs vary greatly. While there are fish that lay millions of eggs and leave them unattended until the male fertilizes, male emperor penguins take care of their eggs for more than two months, leaving even to eat. On the other hand, there are birds that lay a few dozen eggs throughout the breeding season while some turtles lay more than a hundred.

In this other lesson we will discover the differences between viviparous, oviparous and ovoviparous animals so that you know better the different forms of animal reproduction.

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Possibly one of the best known oviparous species is birds. As we saw in the previous section on oviparous animals: definition and examples that we were advancing, birds usually take good care of their young. Birds are oviparous, internally fertilized animals with dry eggs that usually use hidden laying sites such as rocks or bushes but usually build nests to protect them.

Also during the time it takes to develop the young (chick), the female and sometimes the male, they protect it from the cold or predators. In other species, care goes further and just as humans teach our children to walk, some birds teach their chicks to swim or fly.

Some examples of oviparous animals within the world of birds are: the emperor penguin (Aptenodytes forsteri), the Sparrow (Passer domesticus), Dove (Columba livia), the hen (Gallus gallus domesticus), parakeet (Melopsittacus undulatus), the duck (Anas platyrhynchos domesticus), the stork (Ciconia ciconia), the ostrich (Struthio camelus), the golden eagle (Aquila chrysaetos) or the raven (Corvus corax).

Another of the characteristics of the oviparous that we are going to know will focus on the group of reptiles. They are oviparous with dry eggs and, as we saw in the case of birds, reptiles have dried eggs with hard covers that protect their young from desiccation but not from the cold.

In the case of birds, which are warm-blooded animals, parents often warm the young during incubation, while protecting them from predators. Reptiles are cold-blooded animals, which do not give off heat, so they cannot incubate the eggs with their body. For the young to be at a suitable temperature, reptiles usually place their clutches in sunny areas, and as hidden as possible from predators. Something very common is that bury the eggs, as with some species of turtles.

While most birds take good care of their young, in the case of reptiles this behavior varies greatly. In the case of sea ​​turtlesFor example, the hatchlings are left buried in the sand on the beach and abandoned; they themselves have to finish hatching and walk to the water, at the mercy of predators, and learn to swim on their own. In other cases, such as snakes or crocodiles, the young remain with their parents for a long time, even until they reach adulthood.

Some examples of oviparous reptiles they are: the leatherback turtle (Dermochelys coriacea), the Argentine land turtle (Chelonoidis chilensis), python snakes (Pythonidae spp), Nile crocodile (Crocodylus niloticus), Mississippi alligator (Alligator mississippiensis), the common iguana (Iguana iguana) and the common gecko (Mauritanian Tarentola).

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Another well-known example of oviparous is fish. Oviparous fish lay soft eggs and the clutches are usually thousands or millions of unfertilized eggs.

Although the best known species are those that do not take care of their young, not all have these behaviors: catfish (order of the Siluriformes) or harlequin fish (Trigonostigma heteromorpha), take care of their young both while they are inside the egg and once they have hatched. In this other lesson we will tell you in detail how fish reproduce.

Examples of oviparous fish are: common trout (Salmo trutta), common salmon (Salmo salar), the clown fish (Amphiprion ocellaris) and the oscar fish (Astronotus ocellatus) among many others.

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And we end this lesson with the definition and characteristics of oviparous animals to talk about mammals, one of the most unknown groups. This is possibly due to the fact that most mammals, including man, are viviparous and there are only two oviparous mammals: the platypus (Ornithorhynchus anatinus) and the echidnas (Tachyglossidae).

In both cases, the fertilization of the eggs is internal and each female lays one egg, in the case of the echidna and up to three in the case of the platypus. In addition, these eggs are incubated in two different stages: first, inside the mother for just over 20 days and then, when they go outside, for a few more days. Oviparous mammals show great care for their young, and mothers feed their young with their milk until they are able to feed on solid food.

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• ZooAquarium (September 4, 2013). Oviparous animals, life that hatches from the egg. Recovered from https://www.zoomadrid.com/blog/animales-oviparos-la-vida-que-nace-del-huevo
• Encyclopedia of Examples (2019). "Oviparous animals". Recovered from: https://www.ejemplos.co/20-ejemplos-de-animales-oviparos/
• González, B. (January 28, 2019). What are oviparous animals. Recovered from https://www.ecologiaverde.com/que-son-los-animales-oviparos-1803.html