Search our library of articles, papers and other published materials. You can use keywords or boolean-style search:
An upright giraffe, by analogy with humans, ought to suffer massive oedema in its feet; moreover, when it lowers its head to drink, the blood should rush down into it and be unable to flow up again. New pressure measurements reported on page 59 of this issue by Hargens et al. Show why neither of these things happens, and also contain some surprising observations of highly variable venous pressure (P.) in the leg and of a counter-gravitational gradient of P.
The ability to maintain a relatively constant body temperature is central to the survival of mammals. Giraffes are found in relatively hot rather than cold environments, have a body temperature of 38.5 ± 0.5°C, and must have evolved appropriate thermoregulatory mechanisms to maintain this temperature and to survive in their chosen habitats. Their thermoregulation depends on anatomical features and behavioural and physiological mechanisms. To minimize physiological thermoregulation giraffes orientate their bodies to optimize radiant heat gain and to maximize convective
Many features recommend the giraffe (Giraffa camelopardalis) for behavioural study: it is big, abundant, conspicuous, active by day, reasonably trusting of people, deliberate, and the best self-marked animal in existence. Surprisingly, its social behaviour has been largely neglected. We studied giraffe exclusively for the following periods: February–March, 1975 and January–December, 1977 in the Serengeti National Park, July 1979–June 1980 in the Arusha National Park, and January–October, 1981 in the Tarangire National Park, totalling 3264 hours of observation directed principally to
Hormones are chemical messengers produced by specific organs in the body that travel in the blood to target tissues and influence behavior and physiology. The major hormone of interest to us is progesterone, a steroid hormone produced by the ovary and placenta in females. The body is constantly churning out new hormones, while destroying the old ones in the liver or eliminating them in urine and feces. Our interest lies in the reproductive endocrinology, or hormones related to reproduction, of
Carotid arteries in the giraffe were removed and their structural organization studied with light microscopy. It has been shown that the carotid artery has a largely muscular structure in the adult except for the carotid baroreceptor area located at the carotid‐occipital junction. The fetus carotid has an elastic structure in its caudal portion and a musculo‐elastic structure in its cranial portion. It is proposed here that the muscular structure of the carotid arterial system constitutes part of the structural mechanism
Wild giraffes live in extensive groups in the fission fusion system, maintaining long social distances and loose social bonds. Within these groups, resources are widely distributed, agonistic encounters are scarce and the dominance hierarchy was reported in males only, while never deeply analysed. In captivity, the possibility to maintain inter-individual distances is limited and part of the resources is not evenly distributed. Consequently, we suggest that agonistic encounters should be more frequent, leading to the establishment of the dominance hierarchy.
Because it is so tall, the giraffe, Giraffa camelopardalis, provides an important animal model for investigating adaptive mechanisms to orthostatic (gravitational) pressure changes. Previous physiological studies of the giraffe have concentrated on arterial blood pressures in the heart and neck. Briefly, these investigations revealed that arterial pressure near the giraffe heart is about twice that in humans, to provide more normal blood pressure and perfusion to the brain. Another important question is that of how giraffes avoid pooling of blood
In a year’s study of the giraffe population of the Arusha National Park we identified 462 individuals. The cumulative first sightings of individuals were fitted to a logistic model that gave an estimated total population of 471. Immatures accounted for only 24% of the population. Twenty-two calves were born during the period of study. The giraffe of the Park are divided into ‘North’ (more precisely northeastern) and ‘South’ (southeastern) subpopulations, and although there is no barrier between them, only 3%
The relatively small amount of time spent sleeping by giraffes, can be attributed most directly to the need for constant rumination. This is consonant with the more general ecological notion that sleep patterns in prey species are usually characterized by brief, intermittent periods of sleep.
Food preferences of giraffe have been extensively investigated but few data concerning the chemical composition of the preferred species are available. The present study was aimed at ascertaining whether the differences in chemical composition of leaves of preferred food plants influence food selection. Furthermore, whether there are differences in the chemical composition of the specific plant species utilized at different localities and to provide information on the nutritive value of indigenous trees. Availability of the 54 preferred plant species studied