Egg
- Alternate meaning: Egg, Switzerland.
In some animals, an egg is the zygote, resulting from fertilization of the ovum, which nourishes and protects the embryo.
Reptile eggs, bird eggs, and mammalian monotreme eggs are surrounded by a protective shell, either flexible or inflexible. The study of eggs is called Oology.
Animal's eggs
Eggs are usually incubated by the female. In some species, such as the Whooping Crane, both the male and the female take turns incubating the egg. The cassowary's eggs, however, are incubated only by the male.
The 3.3 pound ostrich egg is the largest existing single cell known to man. (Some dinosaurs had larger eggs.) The hummingbird produces the smallest known egg which weighs half of a gram.
Colors
Different animals produce different colored eggs. The pigments protoporphyrin, biliverdin, and zinc chelate of biliverdin, are responsible for the diversity of egg color. These pigments are secreted by cells in the oviduct wall, and can cause speckles if color is added right before the egg is laid. Reptiles' eggs are all white and it is thought that this was true for all animals long ago.
The eggs of cavity nesting birds such as the woodpecker and the kingfisher, are often bright white, making it easy for the parent to locate them.
In species such as the Common Murre, which nest in large groups, each female's eggs have very different markings, making it easier for females to identify their own egg.
Egg structure
Eggs are usually smooth, but there are exceptions. The cormorant's egg, for example, is quite rough and is very chalky. In contrast, the tinamous has very shiny eggs and the duck has oily and waterproof eggs. Another variation is the cassowary' very heavily pitted eggs.
There are tiny pores in the shell of eggs to allow the unborn animal to breathe. The domestic hen's egg has 7500 pores.
Predation
There are quite a few animals that feed on eggs. Principle predators of the Black Oystercatcher's eggs, for example, include racoons, skunks, minks, river and sea otters, gulls, crows and foxes. The Ermine (Mustela erminea) and long-tailed weasel (M. frenata) steal ducks' eggs.
Eggs in Cooking
Birds' eggs are a common food source. The most-used eggs are chicken, duck and goose, but smaller eggs such as quail eggs are occasionally used as a gourmet ingredient, as are the largest bird eggs, from Ostriches. Eggs are frequently used in both sweet and savoury dishes as a source of protein and/or to bind the other ingredients in a recipe together. Sometimes the whole egg is cooked together. Sometimes the egg yolk is used separately from the egg white.
Many who practice Vegetarianism feel it is acceptable to eat eggs as the bird which lays the eggs is not killed. People concerned about animal welfare are reluctant to eat Battery eggs as Factory farming is considered cruel. Even Free Range eggs sometimes are unacceptable to those who are concerned about animal welfare as it is sometimes felt that alleged free range birds may not be much better off than battery birds.
The primary cooking techniques for savoury eggs are:
Eggs may also be pickled, hard-boiled and refrigerated, or eaten raw, though the latter is not recommended for people who may be susceptible to salmonella, such as the old, the infirm or pregnant women.
When eggs become rotten, the yolk will turn green and the egg will emit a sulphurous smell when broken. Although deemed offensive by most Western palates, fermented eggs are considered a delicacy by some in China, when prepared using a special method which includes letting them sit for three months to age (or rot, depending on one's interpretation).
Eggs as Decoration
- Fabergé eggs are much prized collectors' items. Carl Fabergé was the favourite jeweller of many European Royal houses, including the Romanovs of Russia.
- Easter eggs, also known as Pace eggs, are an ancient symbol of spring and the beginning of new life. They figure in egg hunts, egg rolling contests and egg-tapping.
- Egg decorating is a craft which has become much more popular in recent years.
External links
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