Oviparous animals are the animals that lay eggs. The young ones hatch outside the body. The shell of the egg is made up of a hard coating of calcium carbonate (CaCO3). Eggshell protects the embryo from any external damage. Fertilization in oviparous animals can be external or internal.
Oviparous animals lay one or more than one eggs at the time of reproduction. some of the oviparous animals are birds, amphibians, reptiles, fishes, arthropods and mammals.
Animals that lay eggs are:
- Birds
Usually, birds lay one or two eggs. Birds reproduce by internal fertilization. They lay their eggs in the nest. The nest is a protective frame made of dry leaves, twigs, and muds. Parental care given to the egg till the time of hatching is called Brooding.
Some common examples of birds laying eggs are- hen, sparrow, crow, pigeon, etc.
- Amphibians
Amphibians are both aquatic and terrestrial animals. They usually lay their eggs outside the water. They hide their eggs on leaves in a cluster. In water, they form a jelly-like layer over the eggs to protect it from the predators. Some frogs tend to carry their eggs on their back to help them hatch.
Some common examples of amphibians are- frog, toad, salamander, and newts.
- Reptile
Reptiles lay amniotic eggs. Amniotic eggs have hard eggshells to protect their embryo from drying. They tend to lay more than one eggs and their survival rate is high. Reptiles hide their eggs in holes and burrows.
When the embryo develops fully it breaks out of the eggshell by itself.
Some common examples of reptiles are- snakes, crocodile and sea turtle.
- Fish
Fishes lay their eggs in water. They protect their eggs by forming jelly-like layer all around it. Fishes generally tend to lay hundreds of eggs at a time cause the change of their survival is really low. Some fishes nourish their eggs by holding it in the mouth and releasing it when fully developed. It is called mouthbrooding. The eggs are scattered in water over rocks and even in aquatic plants.
Some common examples of fishes laying eggs are- shark, whale, rohu etc.
- Arthropod
Spiders, Centipedes, Crabs, and butterflies are some of the arthropods which lay hundreds of eggs. Some lay fertilized eggs by internal fertilization and some lay non-fertile egg by external fertilization.
- Mammals
There are only two such mammals which lay eggs. Echidna and Platypus are the only oviparous mammals.
Echidna- Spiny anteater, live in burrows and have spines.
Platypus- They are found in Australia and Tasmania. They have a tail and webbed feet.
