Bird Egg - Shape

Shape

Most bird eggs have an oval shape, with one end rounded and the other more pointed. This shape results from the egg being forced through the oviduct. Muscles contract the oviduct behind the egg, pushing it forward. The egg's wall is still shapeable, and the pointy end develops at the back side. Cliff-nesting birds often have highly conical eggs. They are less likely to roll off, tending instead to roll around in a tight circle; this trait is likely to have arisen due to evolution via natural selection. In contrast, many hole-nesting birds have nearly spherical eggs.

The shape has biological significance. A pointed egg will tend to sit on its side, with the big end tipped upward. The big end contains the air sac and its shell is pierced by a higher density of pores than the more pointed end. Tipping the big end upwards improves oxygen flow to the large head, with the physiologically demanding eyes and brain, that develops in the big end while the tail develops at the more pointed end.

  • Classic oval bird egg (Vanellus spinosus)

  • Almost spherical bird egg (Senegal Parrot)

  • Long, "elliptical" bird egg (Loon)

Read more about this topic:  Bird Egg

Famous quotes containing the word shape:

    “If I commit suicide, it will not be to destroy myself but to put myself back together again. Suicide will be for me only one means of violently reconquering myself, of brutally invading my being, of anticipating the unpredictable approaches of God. By suicide, I reintroduce my design in nature, I shall for the first time give things the shape of my will.”
    —Antonin Artaud (1896–1948)

    “Surely among a rich man’s flowering lawns,
    Amid the rustle of his planted hills,
    Life overflows without ambitious pains;
    And rains down life until the basin spills,
    And mounts more dizzy high the more it rains
    As though to choose whatever shape it wills....”
    —William Butler Yeats (1865–1939)

    “To the intelligent, nature converts itself into a vast promise, and will not be rashly explained. Her secret is untold. Many and many an Oedipus arrives: he has the whole mystery teeming in his brain. Alas! the same sorcery has spoiled his skill; no syllable can he shape on his lips.”
    —Ralph Waldo Emerson (1803–1882)