AppearanceOstriches usually weigh from 63 to 145 kilograms , or as much as two adult humans. Ostriches of the East African race averaged 115 kg in males and 100 kg in females, while the nominate subspecies was found to average 111 kg in unsexed adults. Exceptional male ostriches can weigh up to 156.8 kg . At sexual maturity , male ostriches can be from 2.1 to 2.8 m in height, while female ostriches range from 1.7 to 2.0 m tall. New chicks are fawn in colour, with dark brown spots. During the first year of life, chicks grow at about 25 cm per month. At one year of age, ostriches weigh approximately 45 kilograms . Their lifespan is up to 40–45 years.
The feathers of adult males are mostly black, with white primaries and a white tail. However, the tail of one subspecies is buff. Females and young males are greyish-brown and white. The head and neck of both male and female ostriches is nearly bare, with a thin layer of down. The skin of the female's neck and thighs is pinkish gray, while the male's is blue-gray, gray or pink dependent on subspecies.
The long neck and legs keep their head up to 2.8 m above the ground, and their eyes are said to be the largest of any land vertebrate: 50 mm in diameter; they can therefore perceive predators at a great distance. The eyes are shaded from sunlight from above. However, the head and bill are relatively small for the birds' huge size, with the bill measuring 12 to 14.3 cm .
Their skin varies in colour depending on the subspecies, with some having light or dark gray skin and others having pinkish or even reddish skin. The strong legs of the ostrich are unfeathered and show bare skin, with the tarsus being covered in scales: red in the male, black in the female. The tarsus of the ostrich is the largest of any living bird, measuring 39 to 53 cm in length. The bird has just two toes on each foot , with the nail on the larger, inner toe resembling a hoof. The outer toe has no nail. The reduced number of toes is an adaptation that appears to aid in running, useful for getting away from predators. Ostriches can run at a speed over 70 km/h and can cover 3 to 5 m in a single stride. The wings reach a span of about 2 metres , and the wing chord measurement of 90 cm is around the same size as for the largest flying birds. The wings are used in mating displays and to shade chicks. The feathers lack the tiny hooks that lock together the smooth external feathers of flying birds, and so are soft and fluffy and serve as insulation. Ostriches can tolerate a wide range of temperatures. In much of their habitat, temperatures vary as much as 40 °C between night and day. Their temperature control mechanism relies on action by the bird, which uses its wings to cover the naked skin of the upper legs and flanks to conserve heat, or leaves these areas bare to release heat. They have 50–60 tail feathers, and their wings have 16 primary, four alular and 20–23 secondary feathers.
The ostrich's sternum is flat, lacking the keel to which wing muscles attach in flying birds. The beak is flat and broad, with a rounded tip. Like all ratites, the ostrich has no crop, and it also lacks a gallbladder. They have three stomachs, and the caecum is 71 cm long. Unlike all other living birds, the ostrich secretes urine separately from faeces. All other birds store the urine and faeces combined in the coprodeum, but the ostrich stores the faeces in the terminal rectum. They also have unique pubic bones that are fused to hold their gut. Unlike most birds, the males have a copulatory organ, which is retractable and 20 cm long. Their palate differs from other ratites in that the sphenoid and palatal bones are unconnected.Morphology of the ostrich lung indicates that the structure conforms to that of the other avian species, but still retains parts of its primitive avian species, ratite, structure. The opening to the respiratory pathway begins with the laryngeal cavity lying posterior to the choanae within the buccal cavity. The tip of the tongue then lies anterior to the choanae, excluding the nasal respiratory pathway from the buccal cavity. The trachea lies ventrally to the cervical vertebrae extending from the larynx to the syrinx, where the trachea enters the thorax, dividing into two primary bronchi, one to each lung, in which they continue directly through to become mesobronchi. Ten different air sacs attach to the lungs to form areas for respiration. The most posterior air sacs differ in that the right abdominal air sac is relatively small, lying to the right of the mesentery, and dorsally to the liver. While the left abdominal air sac is large and lies to the left of the mesentery. The connection from the main mesobronchi to the more anterior air sacs including the interclavicular, lateral clavicular, and pre-thoracic sacs known as the ventrobronchi region. While the caudal end of the mesobronchus branches into several dorsobronchi. Together, the ventrobronchi and dorsobronchi are connected by intra-pulmonary airways, the parabronchi, which form an arcade structure within the lung called the paleopulmo. It is the only structure found in primitive birds such as ratites. The largest air sacs found within the respiratory system are those of the post-thoracic region, while the others decrease in size respectively, the interclavicular , abdominal, pre-thoracic, and lateral clavicular sacs. The adult ostrich lung lacks connective tissue known as interparabronchial septa, which render strength to the non-compliant avian lung in other bird species. Due to this the lack of connective tissue surrounding the parabronchi and adjacent parabronchial lumen, they exchange blood capillaries or avascular epithelial plates. Like mammals, ostrich lungs contain an abundance of type II cells at gas exchange sites; an adaptation for preventing lung collapse during slight volume changes.The ostrich heart is a closed system, contractile chamber. It is composed of myogenic muscular tissue associated with heart contraction features. There is a double circulatory plan in place possessing both a pulmonary circuit and systemic circuit.
The ostrich’s heart has similar features to other avian species like having a conically shaped heart, and being enclosed by a pericardium layer. Moreover, similarities also include a larger right atrium volume, and a thicker left ventricle to fulfil the systemic circuit. The ostrich heart has three features that are absent in related birds:
# The right atrioventricular valve is fixed to the interventricular septum, by a thick muscular stock, which prevents back-flow of blood into the atrium when ventricular systole is occurring. In the fowl this valve is only connected by a short septal attachment.
# Pulmonary veins attach to the left atrium separately, and also the opening to the pulmonary veins are separated by a septum.
# Moderator bands, full of purkinje fibers, are found in different locations in the left and right ventricles. These bands are associated with contractions of the heart and suggests this difference causes the left ventricle to contract harder to create more pressure for a completed circulation of blood around the body.
The atrioventricular node position differs from other fowl. It is located in the endocardium of the atrial surface of the right atrioventricular valve. It is not covered by connective tissue, which is characteristic of vertebrate heart anatomy. It also contains fewer myofibrils than usual myocardial cells. The AV node connects the atrial and ventricular chambers. It functions to carry the electrical impulse from the atria to the ventricle. Upon view, the myocardial cells are observed to have large densely packed chromosomes within the nucleus.
The coronary arteries start in the right and left aortic sinus and provide blood to the heart muscle in a similar fashion to most other vertebrates. Other domestic birds capable of flight have three or more coronary arteries that supply blood to the heart muscle. The blood supply by the coronary arteries are fashioned starting as a large branch over the surface of the heart. It then moves along the coronary groove and continues on into the tissue as interventricular branches toward the apex of the heart. The atria, ventricles, and septum are supplied of blood by this modality. The deep branches of the coronary arteries found with in the heart tissue are small and supply the interventricular and right atrioventricular valve with blood nutrients for which to carry out their processes. The interatrial artery of the ostrich is small in size and exclusively supplies blood to only part of the left auricle and interatrial septum.
These purkinje fibers found in the hearts moderator bands are a specialized cardiac muscle fiber that causes the heart to contract. The purkinje cells are mostly found within both the endocardium and the sub-endocardium. The sinoatrial node shows a small concentration of purkinje fibers, however, continuing through the conducting pathway of the heart the bundle of his shows the highest amount of these purkinje fibers.The ostrich is well adapted to hot, arid environments through specialization of excretory organs. The ostrich has an extremely long and developed colon the length of approximately 11-13m between the and the paired caeca, which are around 80 cm long. A well developed caeca is also found and in combination with the rectum forms the microbial fermentation chambers used for carbohydrate breakdown. The catabolism of carbohydrates produces ~ 0.56 g of water that can be used internally. The majority of their urine is stored in the coprodeum, and the faeces are separately stored in the terminal colon. The coprodeum is located ventral to the terminal rectum and urodeum . Found between the terminal rectum and coprodeum is a strong sphincter. The coprodeum and cloaca are the main osmoregulatory mechanisms used for the regulation and reabsorption of ions and water, or net water conservation. As expected in a species inhabiting arid regions, dehydration causes a reduction in faecal water, or dry feces. This reduction is believed to be caused by high levels of plasma aldosterone, which leads to rectal absorption of sodium and water. Also expected is the production of hyperosmotic urine; cloacal urine has been found to be 800 mosmol/L. The U:P ratio of the ostrich is therefore greater than one. Diffusion of water to the coprodeum from plasma across the epithelium is voided. This void is believed to be caused by the thick mucosal layering of the coprodeum.
Ostriches have two kidneys, which are chocolate brown in color, granular in texture, and lie in a depression in the pelvic cavity of the dorsal wall. They are covered by peritoneum and a layer of fat. Each kidney is about 300 mm long, 70 mm wide, and divided into a cranial, middle, and caudal sections by large veins. The caudal section is the largest, extends into the middle of the pelvis. The ureters leave the ventral caudomedial surface and continue caudally, near the midline into the opening of the urodeum of the cloaca. Although there is no bladder, a dilated pouch of ureter stores the urine until it is secreted continuously down from the ureters to the urodeum until discharged.
NamingFive subspecies are recognised:
⤷ Common ostrich complex:
⤷ *''S. c. australis'', Southern ostrich, southern Africa. It is found south of the rivers Zambezi and Cunene. It is farmed for its meat, leather and feathers in the Little Karoo area of Cape Province.
⤷ *''S. c. camelus'', North African ostrich, or red-necked ostrich, North Africa. Historically it was the most widespread subspecies, ranging from Ethiopia and Sudan in the east throughout the Sahel to Senegal and Mauritania in the west, and north to Egypt and southern Morocco, respectively. It has now disappeared from large parts of this range, and it only remains in 6 of the 18 countries where it originally occurred, leading some to consider it Critically Endangered. It is the largest subspecies, at 2.74 m in height and up to 154 kilograms in weight. The neck is pinkish-red, the plumage of males is black and white, and the plumage of females is grey.
⤷ *''S. c. massaicus'', Masai ostrich, East Africa. It has some small feathers on its head, and its neck and thighs are pink. During the mating season, the male's neck and thighs become brighter. Its range is essentially limited to southern Kenya and eastern Tanzania and Ethiopia and parts of southern Somalia.
⤷ *''S. c. syriacus'', Arabian ostrich or Middle Eastern ostrich, Middle East. Was formerly very common in the Arabian Peninsula, Syria, and Iraq; it became extinct around 1966.
⤷ *''S. c. molybdophanes'', Somali ostrich, southern Ethiopia, northeastern Kenya, and Somalia. The neck and thighs are grey-blue, and during the mating season, the male's neck and thighs become brighter and bluer. The females are more brown than those of other subspecies. It generally lives in pairs or alone, rather than in flocks. Its range overlaps with ''S. c. massaicus'' in northeastern Kenya.
Some analyses indicate that the Somali ostrich may be better considered a full species, but there is no consensus among experts about this. The Tree of Life Project and IOC recognize it as a different species, but ''The Clements Checklist of Birds of the World'', ''Howard and Moore Complete Checklist of the Birds of the World'' and BirdLife International do not. As of 2010 BirdLife International is reviewing the proposed split. Mitochondrial DNA haplotype comparisons suggest that it diverged from the other ostriches not quite four mya due to formation of the East African Rift. Hybridization with the subspecies that evolved southwestwards of its range, ''S. c. massaicus'', has apparently been prevented from occurring on a significant scale by ecological separation, the Somali ostrich preferring bushland where it browses middle-height vegetation for food while the Masai ostrich is, like the other subspecies, a grazing bird of the open savanna and ''miombo'' habitat.
The population from Río de Oro was once separated as ''Struthio camelus spatzi'' because its eggshell pores were shaped like a teardrop and not round. However, as there is considerable variation of this character and there were no other differences between these birds and adjacent populations of ''S. c. camelus'', the separation is no longer considered valid. This population disappeared in the latter half of the 20th century. There were 19th-century reports of the existence of small ostriches in North Africa; these are referred to as Levaillant's ostrich but remain a hypothetical form not supported by material evidence.
DistributionOstriches formerly occupied Africa north and south of the Sahara, East Africa, Africa south of the rain forest belt, and much of Asia Minor. Today ostriches prefer open land and are native to the savannas and Sahel of Africa, both north and south of the equatorial forest zone. In Southwest Africa they inhabit the semi-desert or true desert. They rarely go above 100 m . Farmed ostriches in Australia have established feral populations. The Arabian ostriches in the Near and Middle East were hunted to extinction by the middle of the 20th century. Ostriches have occasionally been seen inhabiting islands on the Dahlak Archipelago, in the Red Sea near Eritrea.
StatusThe wild ostrich population has declined drastically in the last 200 years, with most surviving birds in reserves or on farms. However, its range remains very large ), leading the IUCN and BirdLife International to treat it as a species of Least Concern. Of its 5 subspecies, the Middle Eastern ostrich became extinct around 1966, and the North African ostrich has declined to the point where it now is included on CITES Appendix I and some treat it as Critically Endangered.
BehaviorOstriches normally spend the winter months in pairs or alone. Only 16 percent of ostrich sightings were of more than two birds. During breeding season and sometimes during extreme rainless periods ostriches live in nomadic groups of five to 100 birds that often travel together with other grazing animals, such as zebras or antelopes. Ostriches are diurnal, but may be active on moonlit nights. They are most active early and late in the day. The male ostrich territory is between 2 and 20 km2 .
With their acute eyesight and hearing, ostriches can sense predators such as lions from far away. When being pursued by a predator, they have been known to reach speeds in excess of 70 km/h , and can maintain a steady speed of 50 km/h , which makes the ostrich the world's fastest two-legged animal. When lying down and hiding from predators, the birds lay their heads and necks flat on the ground, making them appear like a mound of earth from a distance, aided by the heat haze in their hot, dry habitat.
When threatened, ostriches run away, but they can cause serious injury and death with kicks from their powerful legs. Their legs can only kick forward. Contrary to popular belief, ostriches do not bury their heads in sand to avoid danger. This myth likely began with Pliny the Elder , who wrote that ostriches "imagine, when they have thrust their head and neck into a bush, that the whole of their body is concealed." This may have been a misunderstanding of their sticking their heads in the sand to swallow sand and pebbles, or, as National Geographic suggests, of the defensive behavior of lying low, so that they may appear from a distance to have their head buried.
FoodThey mainly feed on seeds, shrubs, grass, fruit and flowers; occasionally they also eat insects such as locusts. Lacking teeth, they swallow pebbles that act as gastroliths to grind food in the gizzard. When eating, they will fill their gullet with food, which is in turn passed down their esophagus in the form of a ball called a bolus. The bolus may be as much as 210 ml . After passing through the neck the food enters the gizzard and is worked on by the aforementioned pebbles. The gizzard can hold as much as 1,300 g , of which up to 45% may be sand and pebbles. Ostriches can go without drinking for several days, using metabolic water and moisture in ingested plants, but they enjoy liquid water and frequently take baths where it is available. They can survive losing up to 25% of their body weight through dehydration.In Roman times, there was a demand for ostriches to use in ''venatio'' games or cooking. They have been hunted and farmed for their feathers, which at various times have been popular for ornamentation in fashionable clothing . Their skins are valued for their leather. In the 18th century they were almost hunted to extinction; farming for feathers began in the 19th century. At the start of the 20th century there were over 700,000 birds in captivity. The market for feathers collapsed after World War I, but commercial farming for feathers and later for skins and meat became widespread during the 1970s. Ostriches are so adaptable that they can be farmed in climates ranging from South Africa to Alaska.
Ostriches were farmed for their feathers in South Africa beginning in the 19th century. According to Frank G. Carpenter, the English are credited with first taming ostriches outside Cape Town. Farmers captured baby ostriches and raised them successfully on their property, and were able to obtain a crop of feathers every seven to eight months instead of killing wild ostriches for their feathers.
It is claimed that ostriches produce the strongest commercial leather. Ostrich meat tastes similar to lean beef and is low in fat and cholesterol, as well as high in calcium, protein and iron. Uncooked, it is dark red or cherry red, a little darker than beef.
PredatorsAs a flightless species in the rich biozone of the African savanna, the ostrich must face a variety of formidable predators throughout its life cycle. Animals that prey on ostriches of all ages may include cheetahs, lions, leopards, African hunting dogs, and spotted hyena. Ostriches can often outrun most of their predators in a pursuit, so most predators will try to ambush an unsuspecting bird using obstructing vegetation or other objects. A notable exception is the cheetah, which is the most prolific predator of adult ostriches due to its own great running speeds.
Common predators of nests and young ostriches include jackals, various birds of prey, warthogs, mongoose and Egyptian vultures. If the nest or young are threatened, either or both of the parents may create a distraction, feigning injury. However, they may sometimes fiercely fight predators, especially when chicks are being defended, and have been capable of killing even their largest enemies, the lions, in such confrontations.
EvolutionThe earliest fossil of ostrich-like birds is the ''Palaeotis'' living near the Asiatic steppes from the Middle Eocene, a mid-sized flightless bird that was originally believed to be a bustard. Apart from this enigmatic bird, the fossil record of the ostriches continues with several species of the modern genus ''Struthio'' which are known from the Early Miocene onwards. While the relationship of the African species is comparatively straightforward, a large number of Asian species of ostrich have been described from fragmentary remains, and their interrelationships and how they relate to the African ostriches are confusing. In China, ostriches are known to have become extinct only around or even after the end of the last ice age; images of ostriches have been found there on prehistoric pottery and petroglyphs.
Several of these fossil forms are ichnotaxa and their association with those described from distinctive bones is contentious and in need of revision pending more good material.
In Subsaharan Africa:
⤷ ''Struthio coppensi''
⤷ ''Struthio karingarabensis'' – oospecies
⤷ ''Struthio kakesiensis'' – oospecies
⤷ ''Struthio oldawayi'' – probably subspecies of ''S. camelus''
⤷ ''Struthio daberasensis'' – oospecies
In Eurasia and N. Africa:
⤷ ''Struthio linxiaensis''
⤷ ''Struthio orlovi''
⤷ ''Struthio karatheodoris''
⤷ ''Struthio wimani''
⤷ ''Struthio brachydactylus''
⤷ ''Struthio chersonensis'' – oospecies
⤷ Asian Ostrich, ''Struthio asiaticus''
⤷ Giant Ostrich, ''Struthio dmanisensis''
⤷ ''Struthio anderssoni'' [oospecies ]
Some text fragments are auto parsed from Wikipedia.