All kinds of animals come from eggs. It's called being oviparous, and it includes all reptiles, all birds, all fish, all amphibians, and even a special group of mammals known as monotremes. That latter group covers species like the echidna and also the platypus.
Some egg-laying species use internal fertilization, in which the egg is fertilized while it is still within the female, while others use external, where the male fertilizes the egg after the female lays them. Different approaches are then used to bring the egg safely through to hatching. In the case of many birds, they will sit on the nest in order to warm the eggs, leaving them only to seek food. Some species, like frogs, ants, and many kinds of fish, take more of a scattershot approach and just have millions of eggs in the hope that some percentage of them will survive. Other species, like the penguin, lay only a single egg and thus tend very carefully and lovingly to it, carrying it with them to keep it off the freezing ground. Still further species bury their eggs for safety, and then there's the seahorse, which, in common with the penguin, has the male tends the eggs -- in this case, by carrying them around in his belly!
We'll never know which came first, the chicken or the egg -- but as long as we can tell which egg we've got handy, we'll know what's coming next. Let's find out!
This flightless bird is the largest and heaviest bird in the world, with a weight of 320 pounds. Ostriches tend to live together in groups of 10 and are guarded by the dominant male of the group-which also serves as the main breeding partner of the female ostriches.
The Tinamou bird of Central and South America produces eggs that continue to amaze researchers and bird lovers. Unlike the chicken egg, the tinamou eggs are shiny and colorful, usually are bright blue. Tinamous nest all their young together in one spot and it is believed that the brightly colored eggs are produced to signal the other females to the nesting ground.
Clownfish, also known as anemonefish, enjoy a symbiotic relationship with the sea anemone, which it uses during its reproduction process. It begins when the male pursues the female by chasing her and showing off his fins then waiting for her to lay her eggs next to the sea anemone; in the nest, he has already cleared and designated for her.
This reptile is known for its aggressive behavior during the breeding period, particularly the male. The pregnant female lays about 12-40 eggs in the chamber she has made, and it will take 60-120 days to hatch. Most mothers do not stick around their nests, so, unfortunately, no motherly care is given to the young tortoise.
Sharks are fierce marine animals that have three main means by which they reproduce: oviparity, ovoviviparity, and viviparity, with ovoviviparity being the most common. In oviparity, the female lays an egg enclosed in a leather-like protective case and is left on the seabed or attached to a reef, during the 6-9 months the shark develops.
This small animal becomes a predatory insect soon after birth. Females lacewings may release more than 200 eggs onto leaves and other foliage, where the tiny larvae hatch just days later.
The aggressive mating process of the crocodile usually begins in the summer months of July- August. The pregnant female is attentive to the 40-60 eggs that she lays, and will stay nearby to guard them against predators and to listen to for the cry of her young when they hatch. Approximately 80 days after fertilization the eggs will hatch, and their sex is determined by the temperature of the nest.
This brightly colored bird can be found in several countries such as the United States, Mexico and Canada. The nest that the female builds may be used for more than one brood and she will incubate the eggs for 12-14 days until they hatch.
This bird can be found on high isolated ledges where it stalks its prey and also nests. The female chooses the nesting site and can lay as many as five light pink or dark brown or purple eggs. She incubates the eggs for about 33 days while the male provides food and safety for her and their young.
Echidnas, which are also known as spiny anteaters, are one of the only two mammals that lay eggs. The males are crude maters that breed hibernating females, resulting in female echidnas that can rise from their slumber pregnant. The females lay only one egg which they store in their pouch until it hatches ten days later. The young echidnas are nurtured with milk secreted from glands found in the same pouches they hatch in.
The golden plover is found in the eastern countries of Asia and the cold temperatures of Alaska. The plover lays about four eggs at a time, which are either black, dark brown or spotted in color. Young plovers are also mobile soon after hatching.
Robins usually begin to breed in March and produce small, distinctive blue eggs, due to the pigment in the mother's blood. The female lays about three or four eggs, which she incubates for two weeks before they hatch. They both work closely together to care for their young; the male does not sit on the eggs but instead provides food for the mother during the process.
Frogs practice sexual reproduction and their young hatch from eggs. Six to 21 days after fertilization, the eggs hatch, tadpoles are formed and adult frogs are developed several weeks later. Though most frogs reproduce in this manner, there are a few species that lay their eggs on land or carry them in sacks in their bodies.
Blackbirds breed during the early spring in March until summertime in late July, but it is not uncommon to find chicks nesting in August. The mother incubates by herself for about two weeks before the eggs are hatched and then the male joins her in feeding their chicks.
Nighthawks are spotted birds of black, brown and gray that can be found in the forests, marshes and grasslands of North America. The mother does not create any particular nest for her young but will lay her two eggs directly on rocky ground or sand or even on the roofs of buildings. The female incubates the eggs, which hatch after 16-20 days, and both parents feed them insects at dawn and dusk.
This monogamous bird usually finds a partner at the beginning of the breeding season in April, and nest building begins soon afterward. The female catbird builds her bulky nest over a 5-6-day period with a little help from her male partner. She incubates 1-5 eggs for two weeks before the helpless young chicks are hatched. They are protected and fed by their parents before leaving the nest 11 days later.
The murre is a large bird that lives near water but breeds in countries such as Alaska and Southern California. The murres stick together and breed in large colonies where the female lays one egg. She incubates the egg for about a month before the chick hatches and is fed by its parents for two weeks.
The mating season begins with male snakes seeking a partner and willing to travel long distances to find one, even resorting to fighting with other males for a female. Snakes may mate for hours, during which time the male inserts his sex organ, the hemipenes, into the female's cloaca and releases sperm. Most snakes incubate for two to three months with the majority laying eggs.
Geese are another example of animals that practice monogamy, usually staying with their partner for life and finding a new one during breeding season if the current partner has died. The five to six eggs laid by the female hatch after they have been incubated for 25-30 days. The male guards the nest during this time and keep a watchful eye on the goslings until they can fly 10 weeks later.
The gray heron is native to Europe, Asia and certain parts of Africa. Herons are large birds that often get mistaken for cranes.
In early spring, grackles form pairs to breed and the two court each other by performing aerial displays and singing together. The female then takes charge, chooses the nesting site and then the two copulate, producing light blue, gray or spotless or spotted eggs. The parents may continue their courtship, but more often than not, the male abandons the mother during incubation and does not return even when the chicks are hatched two weeks later.
Instead of genital organs like humans, birds have cloacas that they use to mate and to expel waste from their bodies. The cloacas swell and bulge out of their bodies during mating season and the male mounts the female and inserts sperm into her cloaca to impregnate her. Females can become sexually mature at seven months and lay about two eggs eight-twelve days after mating.
Male toads are confident maters that signal for the female and jump onto her when she arrives in their territory. The male uses nuptial pads to grip onto the female until she lays about 7,000 eggs that he can fertilize. The jelly-like protective substance seen in frogs is also present in toads and safeguards their young. They hatch several days later, and the tadpoles grow for as many as 70 days.
Unlike other animals, ladybugs do not need to hunt for a partner, but instead they simply secrete chemical pheromones, which will attract a partner that is meant for them. The male will latch onto the female from behind, sometimes for hours at a time, while they mate and he inserts his sperm. The female can store sperm up to two months before releasing black, yellow or orange eggs.
The reproductive organs of this cute animal is a little disturbing but also really cool. The males have penises that look much like a corkscrew and can become erect in half a second and at 20 cm long. Their penises have barbs that can keep away sperm from other males the female may have mated with. A willing female can, however, contract her muscles to relax, allow her eggs to be fertilized before they are eventually hatched 28 days later.
Pheasants are a species of birds native to Asia, recognized by its wattles, vivid colors and long tails in males and brown features and shorter tails in females. The males may engage in combat over the territory, and the winner courts the hen by strutting and showing off his tail. Once courtship has established, the female builds her nest and lays a clutch of 7-15 eggs that hatch after 28 days.
Most snails are hermaphrodites, which means that they possess both male and female sex organs and can fertilize each other. They begin a courtship that can last from 2-12 hours at any point in time and use their tentacles to touch each other or even bite the genital pore that extends outside their bodies. Some species of snails also shoot love darts at each other as a means of sexual play and increasing the likelihood of offspring. After this, copulation occurs, followed by two to four weeks of development.
Adult male octopuses have a hectocotylus, which is the third right arm that is designed to reproduce. He uses this tentacle to insert spermatophore into the female's oviduct or removes the arm and gives it to her to store. In this way, she can use the sperm in the arm to fertilize the egg when she is ready to participate in the reproduction process.
During mating season, the male turtle would mount the female while she swims in the water and would remain on top for up to 24 hours so that no other male can do so. Female turtles nest during the warm summer months, since the temperature determines the sex of her babies. The expectant mother visits the beach repeatedly until all her hundreds of eggs are buried.
The breeding season for this songbird begins in March and ends in August of the same year. Over a three-week period, the female builds a nest all on her own and is made with twigs, mud, leaves and even wood. The female begins her incubation process after all 3-5 eggs are laid- one each day. Thirteen to fifteen days later, the chicks hatch and are brooded by their mother but are fed by both parents.
Platypi are native to Australia and is also one of only two mammals to lay eggs rather than deliver a live birth. The mother cares for them for four months until they can swim in the water. Platypi can also be very territorial, particularly the females that would attack each other with their beaks during the mating season to protect their turf.
Sexual maturity varies among penguins, with the emperor penguins arriving at sexual maturity at five or six years of age, the blue penguin is already mature at two to three years old and the average male at five years old. Courting lasts a few weeks before copulation takes place and the eggs are laid in the pre-made nest.
Quail parents are unlike other animals that tend to separate or abandon their young. Instead, they work together to build a nest that they hide in thick bush to keep away from predators. After copulation, the female lays 12-14 eggs of various colors and spots of dark brown or gray that will hatch after three weeks. The parents then alternate between caring for their young, and the parents stay together for a year.
This elongated fish plays a pivotal role in the survival of its young due to their unique means of reproduction. In this case, the female lays about 400 eggs inside the mouth of the male, where they are fertilized and kept until time for hatching 7-9 days later. The father rotates the eggs in his mouth to keep them hydrated and to provide nutrients to them equally.
Carrion crows are very intelligent animals that begin to build their nests before other birds. As spring nears, they show tell-tale signs of the mating season approaching and begin to carry material for their nests and challenge other birds for territory. During early nesting, the female is noisy but becomes very silent after she was laid her eggs and will go to great lengths to hide it. She lays 3-7 eggs, laying one a day and incubates them until they hatch 18 days later.
This New Zealand bird is known for producing eggs much bigger than its little body and several times the size of a chicken's. The process begins with the mature male kiwi at 18 months and the female at two to three years of age. After the territory is established, a burrow is created and a mate is found. The egg develops in the female after 30 days, followed by a full-blown chick emerging from the shell.
This small ridged shark begins to mate during the months of December and January, followed by the laying of as many as 24 eggs by the female from February to April. The eggs are placed in spiral cases and are wedged between rocks and crevices for protection.
The cuckoo bird is known as a brood parasite because it is known to fly over the nest of another bird's nest and drop any of its 12-22 eggs into it, rather than building a nest of its own. They usually invade the nest of warblers and dunnock birds, but their eggs are sometimes recognized as foreign and removed from the nest.
As one can imagine, from the size of hummingbirds, their eggs are equally as tiny. Experts say that they are the size of jellybeans. Most females lay two eggs and incubate them for 15 to 18 days.
During mating season, large schools of female and male squid can be seen circling each other before pairing up so that mating can take place. The female's bodies are already equipped with an ink sac in their gills where the fertilized eggs will be kept and protected. Meanwhile, the male uses one of its muscular arms to impregnate the female. The expectant mother can lay thousands of eggs, many of which are consumed by predators before eight weeks have passed for hatching to take place. Squid also have short life spans and die soon after mating has occurred.
The mating ritual begins when the male and female seahorses swim, dance and entwine each other. In this instance, the typical gender roles of reproduction are reversed, with the female placing over one thousand eggs into the male's pouch where they are fertilized. He carries it up to 25 days in his pouch where it is nurtured until he gives birth to a small live fry. After birth, the small animals drift in the ocean and are not nurtured further by their parents.
Emus breeding season typically begins in November and lasts until May. The male prepares a nest for the female to lay 7 to 12 large dark green eggs up to 13 cm long, which he then incubates for about 60 days. During this time, he will fast and rarely move from the nest in order to defend it from predators.
For butterflies, the search for a mate begins right after emerging from their pupa. Adult male butterflies use up their sperm mating with a number of females and then die after being fully depleted. Females only lay once for their lifetime, dying after laying all their eggs; they can lay up to 100 eggs on a host plant which serves as a food source for the developing egg.
Starlings nest in suitable holes and cavities, especially in trees, crevices in buildings, utility poles, and holes in cliff faces. Starlings lay about four to six slightly glossy, pale blue eggs that hatch after an incubation period of 11 to 13 days, with their young beginning to fly at 18 to 21 days of age.
The praying mantis's mating season normally occurs at the end of summer and into early autumn. In order to attract a mating companion, the female discharges a pheromone. The process starts after the male has attached himself to the female's thorax. However, this is a deadly affair for males as the females tend to consume the heads of their male counterparts during mating.
In the case of waterbugs, a mating pair exhibits a lengthy and repetitive mating process, which can last several hours. After a successful mating activity, the female then climbs on top of the male and begins to lay a few eggs on his back. Males carry the eggs until they hatch, taking care to expose them to air periodically to prevent the growth of fungus. During this period the male cannot mate.
Chickens, like other birds, reproduce via laying eggs. A hen would lay an egg at least once every other day, as the egg formation process takes approximately 25 hours. However, unless the hen mates with a rooster the eggs will not yield chicks. In natural conditions, hens will lay a clutch of approximately 12 eggs, with each being laid about a day apart.