All About Egg-Laying Animals!
As we enter Spring and Easter draws near, there’s one question that seems to come up again and again. It’s of the more confusing aspects about the Easter holiday – what’s a bunny got to do with eggs? The association between the Easter Bunny, a symbol of Easter, and the colorful eggs the bunny hides around the house for children to find, has always seemed a little strange.
Why is this strange? Because bunnies are not egg-laying animals. Rabbits, like most mammals, are viviparous, which means that their young develop inside the mother, and are birthed into the world live. Oviparous organisms, meanwhile, are animals who lay eggs. Development of baby animals continues within the egg, outside of the mother’s body, until the babies are ready to hatch.
So why does the Easter Bunny apparently lay eggs? We’ll try to answer that question in a bit, but first let’s learn some more about oviparous animals.
Insects & Invertebrates
Most insects and other invertebrates are oviparous, with a few exceptions. In some cases, the baby animal that hatches from the egg looks like a miniature version of the adult. One example of this is the earthworm.
Life Cycle of a Worm
Other times, the hatched animal looks quite different from the grown version. Many insects go through a process called metamorphosis. This is a period in which a juvenile creature in its “larval” stage undergoes a transformation to further develop into its mature, adult stage. The transitional stage is called a “pupa” and sometimes involves the animal wrapping itself into a cocoon as it undergoes the transformation.
Bees, ants, mosquitos, and ladybugs are just a few of the insects that go through this process, but one of the most well-known examples are butterflies and moths, which cocoon themselves to transform from worm-like caterpillars into winged adults.
Life Cycle of a Luna Moth
Most fish (more than 97% of all known species) are egg-laying. However, they often use a technique called ovipularity. Usually, when an egg is laid by an animal, it is already “fertilized” which means the embryo, or baby within the egg, has already started to develop once the egg is laid. However, with ovipularity, the female lays unfertilized eggs, which a male must then fertilize in order for development to start.
Life Cycle of a Salmon Fish
Unlike birds or reptiles, fish eggs usually do not have a hard shell to protect the egg, though in some cases they may have a leathery coating around the egg. In the case of some species of shark, the leathery material and shape of these egg cases led to them being called “mermaid’s purses”.
Not all fish are oviparous, however. Some species of sharks give birth to live young. Seahorses, meanwhile, have a very unique method of giving birth, in which the female deposits her eggs into a pouch near the male’s tummy, where they stay until they emerge into the world, very small but fully developed!
Amphibians & Reptiles
Amphibians like frogs and salamanders usually lay eggs, and typically lay them in water to help keep them wet as they develop. In many cases, the hatched amphibians will undergo a metamorphosis, during which the water-dwelling babies will grow into the air-breathing adults. Many frogs are hatched as tadpoles, which have gills and a tail to help them live in water. Eventually, they will grow legs and lose their tails and lungs as they develop to survive on land.
Life Cycle of a Frog
Some other frogs, however, such as those born in rainforest environments, are hatched as fully formed frogs, and don’t go through the tadpole phase. Other amphibians, like mudpuppies and certain other types of salamanders, never undergo metamorphosis and keep their gills for their whole life, which they spend underwater.
Reptiles, like snakes, lizards, alligators and crocodiles, usually lay eggs with a hard or leathery shell. However, some snakes like boa constrictors and vipers have developed to give birth to live young instead of laying eggs.
Marine Life Rescue Sea Turtle Hatchling Plush
Reptiles often have an “egg tooth”. This is a sharpened area near the tip of the snout that hatching babies use to pierce the shell when they’re ready to greet the world. In lizards and snakes, this is an actual tooth. In crocodiles and alligators, it’s a sharp piece of skin that the body reabsorbs shortly after hatching.
All birds lay eggs with a hard shell. Unlike the other types of animals discussed so far, there are no examples of birds that give birth to live young. Like reptiles, most birds utilize an “egg tooth” to hatch, which gets absorbed back into the beak or falls off after hatching.
Many species of birds build nests for their eggs, which usually takes the form of a cup or bowl-like structure made of out grass, twigs and plant matter. Some species create very intricate woven structures. Others may dig a burrow, or lay their eggs in the hollow of a log, while others may do little more than scrape a shallow depression in the dirt. Emperor penguins keep their eggs warm by tucking them in between their legs.
Emperor Penguin with Baby
Some birds are born helpless and blind, with little or no feathers, and remain dependent on their parents for quite some time after hatching. Others are born fully feathered, and are able to take care of themselves shortly after hatching.
As we mentioned, bunnies and most other mammals do not lay eggs. That doesn’t mean that aren’t exceptions to the rule, however! Mammals that lay eggs are known as “monotremes”. It is believed that monotremes are descended from a more primitive group of mammals, and this is why they still lay eggs as opposed to giving birth to live young.
There are two types of monotremes, the platypus and the echidnas (which are also known as spiny anteaters). Both types are found only in and around the Australian continent. The platypus is a very unique mammal, that looks a bit like a beaver with a face like a duck. Echidnas, meanwhile, have long snouts like anteaters, but are covered in spiky fur like hedgehogs.
Monotremes lay small, leathery eggs. Upon hatching, they nurse their young with milk, like other mammals.
But What About the Easter Bunny?
And now we come back to the original question posed at the beginning of this writing – Why is the Easter Bunny shown to lay colorful eggs? The answer has nothing to do with biology, and everything to do with the history of Easter as both a Christian holiday and signifier of the coming of Spring.
Some believe that the custom of associating eggs with Easter dates back to the Middle Ages, when Christians did not eat eggs during Lent, but were allowed to eat them once Easter arrived. While they couldn’t eat them, they were allowed to decorate and color them with dyes.
Palm Pals 5" Bunny Plush
What about the bunny? Well, rabbits are known to give birth to large litters of babies, which make them a common symbol of new life. Thus, rabbits have come to be associated with Spring and fertility.
Interestingly, it’s not always the bunny doing the work of bringing colorful eggs to children during Easter. In Switzerland, the duty falls to the cuckoo bird. Meanwhile, in some parts of Germany, the role is handled by the fox!