An Overview on Oviparous Animals
The word ‘oviparous’ refers to the animals that reproduce or start new generations by laying eggs. Even though fertilization occurs externally or internally, the eggs are always hatched in the external environment. The hatching never occurs inside the womb of the mother. These animals are capable of laying one or several eggs.
Types of Oviparous Animals:
Animals like amphibians, fish, birds and reptiles are oviparous. Let us learn about these oviparous animals in detail:
Frogs, salamanders and newts are amphibian animals. These animals can live both inside and outside water, but need to remain moist at all times. Amphibian animals lay eggs which are fertilized externally by the male animals. After fertilization, the female amphibian lays her eggs in ponds or other water bodies.
Amphibians mostly emerge from the egg in their larval form. These larvae have tiny tails and gills, which helps them to continue development inside the water body or pond. Gradually, the larva grows into an adult by losing its tail and developing larger limbs.
The female fish discharges her eggs in tiny sand holes or amongst aquatic plants. The male fish later releases his sperms on the eggs. Both male and female fishes suspend their eggs and sperms into the environment and hope that they find each other. Fishes such as Bagrid catfish, store the fertilized eggs in their mouths in order to protect the eggs from potential predators.
Reptiles include snakes, crocodiles, turtles and lizards. Reptiles live both on land and in water. As predators are around, there is a high risk of losing eggs to predators, which leads to low species survival rate. This is why reptiles and amphibians tend to lay large amounts of eggs, sometimes as many as hundred eggs.
Majority of birds lay one or two eggs. The birds who lay one or two eggs, do not survive for long periods of time in the wild. These birds spend most of their time protecting their eggs from possible predators. For example, the little tinamou bird which lays one or two eggs. Whereas birds like Wood duck, which can lay 7 to 14 eggs per clutch, have a higher survival rate. These birds don’t need to stay that long with their eggs.
Most of the arthropods such as hexapods, myriapods, crustaceans, and arachnids are oviparous. Millions of arthropods like spiders, crabs and centipedes are capable of laying hundreds of eggs. While some eggs are fertilized through internal fertilization, the other non-fertile eggs need external fertilization.
Few Disadvantages of Oviparity:
- The mother needs to protect or hide their eggs during development. If not protected, they fall bait to several predators in the environment.
- Oviparous offspring require more time and energy for development. This may cause distress to the mother and result in fewer offspring.
- There is a lack of mobility during the egg development period. The eggs of an oviparous animal need to remain stationary at one place. The mother can move her young once they have hatched.
When the offspring develops outside their mother, this type of reproduction greatly benefits the survival rate of the species. Therefore, oviparous animals have a higher rate of survival than animals who do not lay eggs for reproduction.
Different oviparous animals protect their eggs in different ways. While birds incubate and monitor their egg’s development, the turtles dig a huge hole in the sand and lay their eggs in those holes for protection from predators.
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