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Portal:Biology

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  • Darlingtonia californica — California pitcher plant This patch of Darligtonias is the northernmost natural patch.
    Darlingtonia californica — California pitcher plant This patch of Darligtonias is the northernmost natural patch.
  • Harvestman (Opilio canestrinii), male, on a geranium flower. He is cleaning his leg by drawing it through his jaws.
    Harvestman (Opilio canestrinii), male, on a geranium flower. He is cleaning his leg by drawing it through his jaws.

Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are composed of at least one cell that processes hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms can regulate their own internal environments. (Full article...)

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A brown, black and white bird soars against a blue sky, with its wing and tail feathers spread.
Red kite (Milvus milvus) in flight, showing remiges and rectrices

Flight feathers (Pennae volatus) are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (/ˈrɛmɪdʒiːz/), singular remex (/ˈriːmɛks/), while those on the tail are called rectrices (/ˈrɛktrɪsiːz/ or /rɛkˈtraɪsiːz/), singular rectrix (/ˈrɛktrɪks/). The primary function of the flight feathers is to aid in the generation of both thrust and lift, thereby enabling flight. The flight feathers of some birds perform additional functions, generally associated with territorial displays, courtship rituals or feeding methods. In some species, these feathers have developed into long showy plumes used in visual courtship displays, while in others they create a sound during display flights. Tiny serrations on the leading edge of their remiges help owls to fly silently (and therefore hunt more successfully), while the extra-stiff rectrices of woodpeckers help them to brace against tree trunks as they hammer on them. Even flightless birds still retain flight feathers, though sometimes in radically modified forms.

The remiges are divided into primary and secondary feathers based on their position along the wing. There are typically 11 primaries attached to the manus (six attached to the metacarpus and five to the phalanges), but the outermost primary, called the remicle, is often rudimentary or absent; certain birds, notably the flamingos, grebes, and storks, have seven primaries attached to the metacarpus and 12 in all. Secondary feathers are attached to the ulna. The fifth secondary remex (numbered inwards from the carpal joint) was formerly thought to be absent in some species, but the modern view of this diastataxy is that there is a gap between the fourth and fifth secondaries. Tertiary feathers growing upon the adjoining portion of the brachium are not considered true remiges. (Full article...)

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