Do you know what the word “oviparous” means? It is a term used to describe animals that lay eggs.
Unlike viviparous animals, which give birth to live young, oviparous animals lay eggs that will eventually hatch and produce offspring. There are many different types of oviparous animals, from fish and amphibians to reptiles and birds.
What is the difference between Oviparous and Viviparous Animals?
Oviparous animals are animals that lay eggs, and viviparous animals are animals that give birth to live young.
The main difference between the two is how the offspring develop. With oviparous animals, the eggs are fertilized and then laid outside of the body. The egg then hatches and the offspring develops inside the egg until it is ready to be born. With viviparous animals, the fertilized eggs are retained inside the body of the mother and then the offspring are born live.
There are many different types of oviparous animals, including reptiles, birds, insects and fish. Some examples of viviparous animals are mammals, such as humans, dogs, and cats. There are a few oviparous mammal species which we’ll learn about.
Examples of Oviparous Animals
One of the most well-known oviparous animals is the chicken.
Chickens (Gallus domesticus) cannot fly. There are over 150 different breeds of chicken that come in various colors, patterns and sizes. The chicken is believed to have descended from the wild Indian and south-east Asian Red Junglefowl which is biologically classified as the same species.
With a population of more than 33 billion in 2020, there are more chickens in the world than any other bird. Chickens provide two sources of food frequently consumed by humans: their meat, also known as chicken, and eggs which they lay. Did you know that a chicken’s egg takes about 21 days to hatch?
The life span of a chicken varies between 5 – 7 years although there have been cases of chickens living 20 years or so.
The Duck-billed Platypus (Ornithorhynchus anatinus) is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. The Platypus is one of the few venomous mammals whereby the male Platypus has a spike on the hind foot which delivers a venom capable of causing severe pain to humans, they also use it to kill small animals in self defence. Female Platypus are not venomous.
Together with the four species of echidna, the Duck-billed Platypus is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young. After an egg hatches, the tiny baby (called a puggle) drinks its mother’s milk, which comes from tiny openings in the mother’s belly.
Duck-billed Platypuses have a life span of 10 – 17 years.
Brazilian Wandering Spider
The Brazilian Wandering Spider (Phoneutria fera) is an aggressive and highly venomous spider. It was first discovered in Brazil hence its name. However, this genus is known to exist elsewhere in South and Central America.
Brazilian Wandering spiders reproduce by means of eggs, which are packed into silk bundles called egg sacs. All species of spider are oviparous. The male spider must (in most cases) make a timely departure after mating to escape before the females normal predatory instincts return.
Mature male spiders have swollen bulbs on the end of their palps for this purpose and this is a useful way to identify whether the spider is male or female. Once the sperm is inside the female spider, she stores it in a chamber and only uses it during the egg-laying process, when the eggs come into contact with the male sperm for the first time and are fertilized.
The Brazilian Wandering spiders life cycle is 1 – 2 years.
The Australian Pelican is found across Australia and New Guinea on many inland and coastal waters but tends to avoid the very dry desert regions mainly located in the centre of the continent. Australian Pelicans are large shore birds who measure 1.6 – 1.9 metres (5.3 – 6.2 feet) in length and weigh 4 – 6.8 kilograms with some larger birds weighing up to 8.2 kilograms.
Australian pelicans have a very large wingspan of 2.5 – 3.4 metres (8.2 – 11.2 feet). Females are slightly smaller than males. Their plumage is white and their primary wing feathers are black and they have black markings on their tails. They also have a very long beak which measures 50 cm.
The female pelican lays 1 – 3 chalky-white eggs which measure 93 x 57 millimetres and become soiled and scratched as incubation is performed on the parents feet. Both male and female take turns to incubate the eggs. After 32 – 37 days, the eggs hatch and the pelican chicks are born naked and blind. The first hatchling is always larger and is fed the most food by the parents. The smaller hatchling may starve and die because of this or even may be attacked by its larger sibling.
The Australian Pelican matures and is able to breed at the age of 2 – 3 years. Their life span in the wild is between 10 and 25 years.
A butterfly is a flying insect of the order ‘Lepidoptera’ (an order of insects with broad wings which have minute overlapping scales). In Greek, ‘Lepidoptera’ means ‘scaled wings’. This order belongs to the superfamily ‘Hesperioidea’ or ‘Skippers’ as they are commonly called. ‘Skippers differ from butterflies in that they have thicker bodies, better eyes, stronger wing muscles and hooked-back antennae.
Many butterflies have striking colors and patterns on their wings. Butterfly wings are actually transparent – it is the over-lapping scales that give the wings the colors that we see.
Butterflies pass through four distinct phases of metamorphosis. First, the eggs hatch into larvae, better known as caterpillars. In some species the caterpillars are cannibalistic. After a while, the caterpillars wrap themselves in a protective enclosure, called a chrysalis. At this stage the insects are called pupae. After some time, pupation ends and the mature butterfly emerges from its chrysalis. The butterfly then mates and lays it’s eggs on plants.
The average lifespan for an adult butterfly is just 20 to 40 days.
The Crocodile is a large aquatic reptile that lives throughout the Tropics in Africa, Asia, the Americas and Australia. Crocodiles tend to congregate in freshwater habitats like rivers, lakes, wetlands and sometimes in brackish water (water that is saltier than fresh water, but not as salty as seawater).
Some species, particularly the Saltwater Crocodile of Australia, Southeast Asia and the Pacific islands often live along the coastal areas. Crocodiles are also known to venture far out to sea. Crocodiles are an ancient lineage and are believed to have changed little since the time of the dinosaurs.
After crocodiles mate, the female crocodile lays about 20 – 40 eggs (a clutch) in a nest she makes near a river bank once a year. She covers the nest with leaves and other vegetation. The rotting vegetation keeps the eggs warm and the nest moist. The incubation temperature for crocodile eggs is 28 – 32 degrees Celsius, relative humidity is 95 – 100 per cent, incubation period is 70 – 80 days. The female stays and guards the nest until the eggs hatch.
The Emu is a large, tough flightless bird found in many parts of Australia and New Guinea. It is Australia’s largest bird and the only member of the Genus: Dromaius. The Emu is the second largest bird in the world.
Male emus are dedicated parents. As the egg laying period approaches, males will lose their appetite and begin to construct a nest using sticks, grass, leaves and bark.
The female emu lays her eggs (on average 11 eggs) which are large, thick-shelled and green in color and then leaves the male emu to do the brooding. The female emu will mate with other males and will produce multiple clutches of eggs.
For the next 8 weeks after the eggs have been laid, the male will sit on the nest, carefully turning the eggs around 10 times each day. An average egg can measure 5 inches long and 3 inches wide and weigh up to 900 grams.
During this brooding time, the male emu may lose one third of his body weight by not feeding while brooding the clutch of eggs. He survives only on stored body fat.
Once the eggs hatch, the male emu will stay with the chicks for the next 18 months, teaching them to hunt for food.
The Komodo dragon (Varanus komodoensis) is a lizard species that is found on the islands (particularly the Komodo Island) in central Indonesia. The komodo dragon is a member of the monitor lizard family and is the largest living species of lizard. Because of their size and because there are no other carnivorous animals, these apex predators dominate the ecosystem in which they live.
The Komodo Dragon breeding season occurs between May and August. Around 20 eggs are laid in September which are deposited in abandoned megapode nests (Megapode – stocky, medium-large chicken-like birds with small heads and large feet). Eggs are incubated for 7 – 8 months, hatching in April the following year when insects are abundant. The young dwell in trees for safety as they are very vulnerable to predators and cannibalistic adult dragons.
The Piranha Fish (also known as the ‘caribe’ in Venezuela) is a ferocious, schooling, fresh-water fish. It is native to warm rainforest lowland streams and lakes in South America – the Amazon basin, in the Orinoco River and east of the Andes Mountains. Piranha Fish have been introduced to other places, including Northern Brazil, Hawaii, parts of the Central and North America.
There are many species of piranha fish. Piranhas reproduce by laying groups of eggs in rivers and lakes.
The breeding environments of piranhas tend to be main bodies of water such as lagoons. Piranhas will change color during spawning with the red belly Piranha fish getting more intense and the whole piranha becoming slightly lighter. The pair will defend their spawning territory and prepare a nest not unlike the breeding behaviour of birds. The female lays clusters of eggs into a bowl shaped nest created in the sediment. These are around 4 or 5 centimetres in depth and 15 centimetres in diameter. The eggs will then be fertilised by the male. The eggs hatch after two to three days, depending on the temperature of the water. The piranha fish parents protect both the eggs and their brood.
Blue Footed Booby
The Blue-footed Booby Bird is a comical-looking tropical seabird with bright blue webbed feet and bluish facial skin.
The name ‘booby’ comes from the Spanish term ‘bubi’, which means ‘stupid fellow’. This is because the Blue-footed Booby is clumsy on the land, and like other seabirds can be very tame. It has been known to alight on boats, where it was once captured and eaten.
The color of the feet in these boobies ranges in the tones of blue from electric blue or indigo blue and even turquoise blue and it has nothing to do either with gender or age of the individuals. Nobody knows why this blue color was selected by nature but it is helpful for the individuals to recognize their own kind.
Most hermit crabs salvage empty seashells to shelter and protect their soft abdomens, from which they derive the name ‘hermit’. There are about five hundred known species of hermit crabs in the world, most of which are aquatic. Hermit crabs live at a range of depths from shallow coral reefs and shorelines to deep bottoms, although some species are terrestrial.
The developing eggs are attached to the abdominal swimmerets present only in the females. A female is able to carry several thousand eggs into the water.
The newly hatched hermit crabs are known as larvae. These young crabs live as microscopic plankton for several weeks before settling on the bottom and searching for a shell to inhabit.
The Ostrich (Struthio camelus – meaning ‘camel-like’) is the worlds largest flightless bird which is native to the savannas and grasslands of South Africa. It has also been introduced to Australia. The ostrich is a member of the ratite (which means flightless bird) family of birds. It is the only living species in the family: Struthionidae and a member of the order:
Struthioniformes which also includes Rheas, Emus, Kiwis and Cassowaries which are also large, flightless birds from different parts of the world.
Ostrich eggs are around 16 centimetres in length, weigh 3 pounds and are glossy and cream in color. They are the largest bird eggs of all. Once hatched (after around 6 weeks), the brood of up to 40 chicks form creches. Sometimes Ostriches steal chicks from other birds to add to their own brood to make it larger.
The male Ostrich is the main carer. The tiny ostriches immediately learn to follow the male, clustering around his feet as they try to keep up with the sometimes formidable strides (3 – 5 metres long) of the group. The male Ostrich shows the chicks how to feed and protects them from predators and the elements using his wings to shelter them from the hot sun.
Centipedes (Class Chilopoda) are fast-moving, venomous, predatory, terrestrial arthropods that have long bodies and many jointed legs. Centipedes are found primarily in tropical climates, however, they are also widely distributed in temperate zones. Despite their name ‘centipede’ (which means ‘100 legs’), all centipedes do not have 100 legs. Centipedes are invertebrates meaning ‘without a backbone or spinal column’.
In temperate areas egg laying occurs in spring and summer but in subtropical and tropical areas there appears to be little seasonality to centipede breeding.
The Lithobiomorpha, and Scutigeromorpha species lay their eggs singly in holes in the soil, the female fills the hole in on the egg and leaves it. The young usually hatch with only 7 pairs of legs and gain the rest in successive molts. Scutigera coleoptera, the American house centipede, hatches with only 4 pairs of legs and has successive molts before becoming a mature adult. It takes about 3 years for some species to achieve adulthood, however, like millipedes, centipedes are relatively long-lived when compared to their insect cousins. Some can live for 5 or 6 years.