ABOUT THIS IMAGE... ‘Dance of the Spirit Guide’

One of my favourite photography destinations is Mokala National Park in the Northern Cape Province of South Africa. This photogenic environment with its great diversity of bushveld types and its large variety of geological formations (rante (ridges), kopjes (hills) and areas of deep sand) frequently also provides great sightings of eland.

Eland are magnificent animals. They are the largest of the antelope species – mature individuals, particularly the old bulls, are massive and the rivals of Cape buffaloes in terms of stature and power. Eland are animals that demand your attention and respect, even though they are nowhere near as belligerent as buffaloes or other big game species are.

The aboriginal inhabitants of Southern Africa recognised this majestic quality of the eland. In San mythology, the Eland occupies a central role in the pantheon of quasi-deities – animals imbued with the power of spirits that can and do act as intermediaries between this world and the eternal, other world of the gods, spirits and ancestors. Indeed, Eland is one of the first and the favourite animal creation of Mantis (more correctly ǀKágge̥n), the demiurge and champion of the San.*

In the San rock art (of most districts of Southern Africa) the eland is depicted more frequently than any other animal species (including the smaller antelope species that were hunted much more often and that provided the San with their staple meat supply – antelope such as kudu, gemsbok, blue wildebeest, common duiker, for example). Moreover, the most elaborate artwork always shows eland, often in polychrome paintings (with many shades of white, ochre and red) and in detail almost never seen in the paintings of other animals. It is clear that to the San paintings of eland are not representations of the animal, the food source, alone; rather the paintings form an important aspect of San spirituality.

In all human societies and cultures, access to the world of the deities and spirits is barred for the majority of mere mortals. Only a few unique, ordained individuals have the necessary power and permission to act as intermediary, as messenger, between this and the other worlds. In ancient tribes, this role fell to the shaman, the medicine man/woman, the high priest/priestess, to name a few monikers of these select individuals.

Probably the most important and significant ritual in San spiritual life involves the ‘great dance’. The great dance is often performed at or near new moon (when the nights are at their darkest) or after a successful hunt of a large and significant animal (like eland, giraffe, kudu and hartebeest). During this ritual, the women of the clan are seated in a large circle around a roaring fire. They sing and clap their hands rhythmically and repetitively. Within the circle, one or more shamans (men and women) lead the circular dance of the men. The dance starts more slowly, with the feet of the dancers stamping the ground hard to the rhythm of the ‘music’; then the dance becomes more and more energetic, with the dancers often mimicking the behaviour and antics of animals. The dance activates the supernatural power of the dead animal – for the San, the eland possess the greatest amount of potent energy. Within the circle illuminated by the light of the fire is the healing power of the shaman(s) and the activated potency of the dead eland (or other large animal); lurking in the dark of night beyond the firelight are the malevolent spirits of the dead who seek to harm the community and to cause sickness.

During the long, exhausting dance, the shaman enters a trance. In this state, the shaman harnesses the potent energy to embark on the perilous journey from this realm to the realm of the spirits and ancestors. In this ‘other’ world, the shaman performs various tasks that are important for the clan: communicating with deities and ancestors, interceding on behalf of the clan, healing of the sick, rainmaking and fighting off evil spirits that are threatening the life and security of the clan.

In the course of the trance, the shaman enters an altered state of consciousness. The visit to the supernatural real on behalf of the clan is accompanied by the experience of entoptic phenomena, such as the ‘seeing’ of bright geometric shapes (zigzags, grids, curved lines), patterns of bright dots of light and vortices of light. The shaman will enter the spiritual realm by sliding down the vortices of light, by slipping through rotating tunnels or by entering holes or caves. On the journey, the shaman will be confronted by ‘monsters’ and by figures of animals with strong spiritual content.

The rock paintings of the San are religious iconography. The potency of the eland is revealed by the frequency of paintings of this species and the lavish care taken in its depiction. Amongst these magnificent paintings, there are depictions of the transformation of shamans themselves into eland (or other antelope). These paintings of standing therianthropes or kneeling ‘trance-buck’, paintings of humans blending and melding with antelope forms to varying degrees, hint at the transformation that the shaman experiences during trance.* *

It is not at all surprising that the eland is of utmost importance in San mythology – the most potent spiritual guide for the shaman. Eland is Mantis’ favourite creature after all. Eland are huge animals (yet extremely agile and fleet-footed), a great reward for a skilled hunter and a large, much-needed supply of protein for the clan. Moreover, eland carry a very large quantity of fat, particularly so the mature bulls – an anomaly since in most other large animals the females will carry more fat than the males do. The fat nourishes, but is also used in many rituals and initiation rites; it also forms, together with the blood of an eland, a spiritually potent medium with which valuable pigments can be mixed for paintings.

On one of my trips to Mokala, I happened across a small herd of eland at dusk. The sun had set already, so the light was gloomy. More than that, the herd was travelling through thick bushveld and in the deep shadow of one of the many rocky ridges. I clicked a few snaps (below par as far as I was concerned). The herd must have caught the scent of my car exhaust fumes because all the animals abruptly started galloping away, parallel to the ridge. To my surprise they returned at great speed, heading back past me a minute later (spooked by an approaching vehicle from the opposite direction as it turned out). I grabbed the camera with a medium focal length lens attached, stopped down the aperture of the lens by two more stops and panned the stampeding herd and the few straggling loners at a very slow shutter speed.

One of the last females to pass in front of me performed a little stot, a jumping action while running. The resulting image I call ‘Dance of the Spirit Guide’.

*          ǀKágge̥n is a trickster deity who is able to shape-shift into the form of any animal. He is most frequently represented as a praying mantis but also takes the form of a bull eland, a louse, a snake, and a caterpillar. His wife, Coti, is represented as a dassie or rock hyrax and is known as the mother of bees. Their adopted daughter is represented as a porcupine.

**      If you are interested in reading more about the enthralling spiritual realm of the San and their rock paintings, the following short article is available online:

Lewis-Williams, J. D. A dream of eland: An unexplored component of San shamanism and rock art. World Archaeology 1987; 19(2): 165-177 (PDF) 

A GRASS MENAGERIE: II - The Inhabitants of the Grasslands

In essence, the smaller denizens of the grasslands (including the myriad of insects inhabiting this biome) live in a forest-like environment – not under a canopy of leaves and between tree trunks, but rather between the culms and the inflorescences of the taller grasses. Their environment is dense and provides for ample opportunities either to shelter or to escape from predators. 

Moreover, these smaller organisms, experience subtle stratification of the environmental factors (such as light intensity, temperature and humidity) from ground level upwards to the top layer of the grasses. These littlies can move up and down in their environment to modify, albeit very slightly, the influence on their tiny bodies of a few environmental factors. For example, any small motile animals living in the grasslands can escape the heat of a summer’s day by moving down to the shaded ground level; they can escape desiccating winds, again by sheltering at the bases of the grasses. Despite these advantages, the differences between day and night are significant and can prove to be challenging to the small inhabitants; at night the grasslands become much colder, as a lot of heat is re-radiated to outer space, while far less heat is trapped in the sparse biomass of the vegetation. Of course, for the larger animals the grasslands are essentially two-dimensional environments, with the subtle changes in environmental conditions proving insignificant (apart from changes from day to night).

For many animal species, the grasslands become uninhabitable during the winter seasons. In general, two responses have evolved to this challenge. Those motile organisms that can not cope with the prolonged dry, cold times will migrate to areas that are more amenable in environmental conditions. The larger herbivores often partake in long-distance migrations, following the patchy and intermittent rainfall. Many bird species are trans-equatorial migrants, using long-distance flight to inhabit grasslands only during the wetter summer months in both hemispheres.

Many of the smaller organisms that are not able to escape from the rigours of the winter season by migration over large distances enter a period of dormancy, often for significant stretches of time. In regions of the planet with warmer climates, many insects living exclusively in grasslands aestivate during the most arid months. Populations of active insects will fluctuate in number seasonally; moreover, the occurrence of large, stable populations of insects in local areas of grasslands tends to be less predictable than in other biomes. A number of insect taxa do cope well with the environmental conditions in grasslands. These include orders of insects such as the Orthoptera (including grasshoppers and locusts) and the Hymenoptera (including ants). The very successful insects consume the leaves of grasses themselves, or they harvest, store and consume the grass seeds.

For the much larger vertebrate herbivores that inhabit the grasslands, food is present in abundance, provided the animals can graze the grasses themselves, feed on the grass seeds or select the herbs nestling deeper down between the grasses. Although the biodiversity of grassland plants is generally very high, the vegetation types available for herbivores is limited to grasses and smaller, usually non-woody flowering plants that grow here. Consequently, the diversity of animal life that is supported by grasslands is impoverished (in general) when compared to other biomes like the woodlands and forests, at least in terms of the number of species that inhabit the grasslands. This is not necessarily the case in terms of the number of individuals that live in the grasslands, since adaptation to this periodic environment has occurred in many groups of organisms (such as the grasses themselves, and the flock-forming seed-eating birds and the herd-forming grazing antelopes).

Amongst the numerous antelope species living in grasslands and open savannas, an interesting correlation exists between the size of individuals of a species and the social behaviour that has evolved in that species. The smaller browsers and grazers require vegetable food sources of high nutritional quality. Their bodies have a small volume compared to their surface area. To keep fuelling the high rate of cellular respiration required to maintain a constant and high core body temperature, these small antelope must be highly selective in the food that they consume. Therefore, small antelope species are solitary or live in small family groups.

In the much bigger herbivores, the quality of the food is not that vital. Inherent in the large size is a decreased ratio between the surface area of the organism and its volume that allows for a slower basal metabolic rate than that found in smaller species. With a small surface area compared to volume, large organisms are not faced with excessive heat loss through their skin. At the same time, the larger volume allows for the digestion of the food to proceed at a slower pace. Large antelope can graze grasses and allow the digestion to take place over time; hence the evolution of multi-chambered stomachs and the behaviour of chewing the cud in the antelope species. The alternative strategy, seen in horses and zebras, for example, involves the evolution of a large caecum; in essence, this is a spacious storage vat in the hindgut in which vegetation can be decomposed by bacterial action. Whatever the anatomy of these larger herbivores, they can survive easily in vast herds since the food they consume is more easily available, albeit of low nutritional value.

Add to this another benefit: the relatively low height of the grassland vegetation allows for vigilance against predators for the larger animal species. Living in a large group means more eyes and ears, as well as a smaller chance that a particular attack by predators will result in the death of any one of the members of the group. (Of course, one of us will die, but the chance of it being I is lessened in a large group.) The ability to live in larger herds has necessitated some form of herd co-operation and control that is complex enough to promote social cohesion, especially during courtship and mating. So vast herds of large grazers occupy the grassland environment, tracking the intermittent rainfall in spectacular long-distance migrations. Their predators, too, follow the migrations, but to a lesser extent – territoriality between carnivores well-equipped with the weapons of their trade can be intense and will limit the movement of groups of predators.

Another feature vital for the survival of mammalian herbivores in grasslands is the production of precocial young, that is, babies that are fully functional very soon after birth. The gestation periods of grassland herbivores is lengthened, in general, and the newborn is able to be on its feet and run with the herd within minutes after birth. In the smaller herbivores, where no herd behaviour is found, the young are precocial nevertheless, although they will often hide in denser vegetation or denser patches of grassland near where the mother is feeding.

The lack of tall vegetation in which predators can conceal themselves has necessitated the evolution of larger carnivores that can run down their prey, rather than relying on concealment and a pounce at close quarters. Three strategies in hunting prey among the larger carnivores prevail in grasslands: sheer speed of pursuit, endurance of long-distance chasers or the use of elaborate hunting strategies in larger social units of predators. Predators that rely only on speed still live either as solitary individuals or in small family groups, usually a female and her offspring only. This is often not the case with the two other groups – the long-distance chasers and the strategic hunters both require the co-operation of several members of the group in order to kill prey. This interdependence of members of a group for effective hunting goes hand in hand with more complex and elaborate social behaviour. Maintaining co-operation in a pack or pride requires social interactions that promote group cohesion, such as appeasement behaviours and social ranking of individuals within the group. Invariably, a hierarchical social system develops in these predatory species.

For the rodents, the omnivores and the smaller carnivores of the grasslands, shelter from the harsh environment, concealment from predators, or safety during reproduction is often found in burrows. The grassland environment, with its relatively deep soils and the top layer of the soil knitted together by the adventitious root systems of the grasses allows deep tunnel systems to be excavated by many animals that have the strength and the equipment (such as large claws) to do so. Subsequent occupation of the burrows by a host of other species – comprising individuals that themselves can not dig effectively – means that these tunnel systems often stay in use for long periods.

Photographing wildlife in grasslands is challenging. The larger species (mammals and birds) will flee readily and they can not be approached without difficulty. The unpredictability of the occurrence in any specific area of larger animal species can be taxing too. For me, portraying the grasslands has remained a test that I accept with glee. To display the magnificence of this biome and its menagerie of inhabitants will remain a special privilege always – particularly so since I too am an original inhabitant of the Highveld’s grasslands.

A GRASS MENAGERIE: I - The Environment of the Grasslands

The world’s grasslands flourish in the middle latitudes of our planet, quite far north and south of the equator; hence, this biome is subjected to pronounced seasonal changes in environmental factors. Grasslands also tend to thrive in the drier interior of continents some distance from the oceans.

Grasslands generally receive moderate, often erratic rainfall, usually in late spring to early summer; the short wet season is followed by prolonged dry periods during which very little precipitation falls. Temperatures in grasslands can fluctuate annually from hot daytimes to very cold winters with significant bouts of frost (at least). Moreover, most grasslands occur on deep soils (often sandy or friable) that do not retain soil moisture for long.

The grasslands survive pronounced seasonal changes in a combination of environmental factors: sufficient warmth and sufficiently long day-lengths for growth, moist upper layers of soil, and frost-free nights in the summer months, with cold and frosty nights, dry soils, and short day-lengths in winter. This combination of factors gives rise to an obvious growing season for the vegetation in late spring and summer, followed by a lengthy dormant season.

In southern Africa, the grasslands are located chiefly in South Africa (on the Highveld (an elevated central plateau) and the inland areas of KwaZulu-Natal and the Eastern Cape) with much smaller, localised regions found particularly in the eastern highlands of Zimbabwe. In general, the topography is flat or undulating, but it includes the escarpment areas of the Highveld and the highlands of Zimbabwe too. The altitude of southern Africa’s grasslands varies from near sea level to close to 3000 metres in elevation.

A copious number of grass species dominates the grasslands extensively. Between the grasses also grow many non-woody flowering plants and many geophytes (bulb-producing plants); regularly woody shrublets can also survive the environmental and climatic conditions experienced in grasslands. Since the height of the vegetation is very low, plants in grasslands experience high light intensities (at least during the summer months); no true shade-plants survive here.

Taller shrubs and trees are generally absent from grasslands. There are several reasons for this absence. The deep and often well-drained soils of grasslands frequently become too dry at deeper levels for tree roots to be able to absorb sufficient moisture. In general, the leaves and smaller twigs of trees and shrubs are also not frost resistant; therefore, taller woody vegetation can not survive the lengthy cold, dry winter seasons. During the winters, fire too becomes a significant ecological factor in grasslands, removing dense old growth from the biome, making nutrients available again for the rapid growth of new grasses during the following growing season. Fire also prevents the encroachment of shrubs and trees into grassland areas.

In contrast to most woody vegetation, grasses can survive the challenging conditions of the dry seasons during which grasses become dormant. In winter, the grasses usually die back; that is, the above-ground culms dry out completely while the below-ground root systems survive the harshest of parched cycles. Alternatively, many grasses are annual plants rather than perennials – the adult lives for one season only, during which time the plant germinates from seed, grows rapidly, flowers and sets seed itself, only to die when the dry season commences. As long as the upper soil layer does not become too hot during a fire, the seeds of the previous summer can survive there and the grasslands can persist even through regular cycles of wildfires. The smaller non-woody herbs, flowering plants and the shrubs of the grasslands follow similar strategies.

Grasses form a special subset of the vegetable world in many ways. Their roots do not penetrate deep into the soil; rather, the many thin, fibrous roots spread out just under the soil surface, knitting together the top layer of soil. The decomposition of the dead leaves, culms and roots of grasses releases nutrients into the topmost, enmeshed and very fertile soil layer. The web of fibrous roots also captures much soil water before it percolates into the deeper strata following good rains. Sacrificing a long life for rapid growth, grasses with their strap-like leaves and thin culms have done away with thick trunks and large leaves. The strategy employed is one of grow, reproduce and set seed as rapidly as possible. In grasslands, plants that do not produce seeds are very rare.

Although they are flowering plants, grasses have done away with large, showy flowers. The grasslands, in general, are often too dry for much of the year to support a permanent, large insect population. There exist vast numbers of insects in grasslands, but their appearance in a local area may be unpredictable. Therefore, attracting a pollinator at the correct time – when the flowers have grown and matured, and are ready for pollination and fertilization – is a challenge for any flowering plant in a grassland environment. Instead, grasses have reverted to wind pollination and the flowers have become minute, but bright, splashes of colour in the inflorescences of grasses. Since most grasses grow to a more or less uniform height and the grass stalks are thin, wind can move over and through grasslands relatively unimpeded, except at ground level. Thus wind pollination is an effective strategy for plant reproduction in this environment.

In contrast to all other plants, the grasses possess a unique feature. In plants that are not grasses, cell division for growth of the organism takes place only in two regions of the plant: at the tips of the roots and twigs (where elongation of all plants takes place), and in woody plants just below the outer covering inside of the bark of larger shrubs and trees (so that an increase in the diameter of roots, trunks and branches can take place). In grasses, however, patches of undifferentiated tissues (the intercalary meristems) occur and cell division can take place at any regular point along the plant. As a consequence, grasses do not stop growing when their leaves and culms are grazed (that is, when the tips of the plants are removed); rather, growth of new plant material will take place from the intercalary meristems. In fact, grasses tend to thrive better if they are grazed to a certain extent. The saliva of the antelopes that graze the grasslands of Africa and elsewhere also stimulates grass growth, an interesting example of co-evolution between a predator and its prey in these two groups that evolved on our planet at the same time.

When people look at grasslands, they may conclude that the biodiversity of this biome is quite low. Grasslands look uniform – there seem to be only grasses present, and these tend to grow to the same length (more or less) in any particular area. However, in South Africa, this biome harbours a tremendously high biodiversity (second only to the fynbos biome of the southern Cape). The grasslands are often home to rare plants, particularly so in the higher-lying areas along the escarpment. These scarce species are often endangered; they comprise mainly endemic geophytes (bulb-producing plants) and dicotyledonous herbaceous plants. However, very few species of grasses are rare or endangered, almost certainly as a result of wind pollination and the production of small seeds.

All my life I have been a resident of the Highveld of South Africa. My earliest recollections of wilderness are intertwined intimately with the grasslands. As a very young photographer, I often lamented the fact that my family had not lived in a bushveld or coastal area – environments that seemed so much more photogenic in themselves and that appeared to be jam-packed with opportunities of capturing images of wildlife. However, the more I explored, the closer I looked at the grasslands surrounding my home, the more grew my appreciation of the spectacular expanses of the grasslands. Nowadays, I relish the challenge of portraying the grasslands in all their splendour; I cherish every opportunity of arresting, in an image, the fabulous grass menagerie.

REMINISCENCES: The Bone-Chewing Giraffe

A few years ago, while visiting a very small game reserve at the foot of the Waterberg Mountains (near Bela-Bela in the Limpopo Province of South Africa), a bull giraffe that was behaving very oddly indeed piqued my curiosity. This old lord of the bushveld was standing in a bare patch of veld, his legs splayed apart slightly, his head held down at ground level. I soon realised that this giraffe was attempting to gather up a small item from the soil using his thick furry lips and long tongue. When he eventually lifted his head, to my surprise, a slither of sun-bleached bone was clenched firmly in his muzzle – then he persisted in rolling this small piece of bone around inside his mouth, chewing on it and sucking on it for the next half an hour.

Bone is an extremely indigestible material. Long-dead bone is essentially a rock, a type of limestone, composed of a crystalline lattice of calcium phosphate and calcium carbonate and other inorganic minerals. Of course, bone has an organic origin; vertebrates produce and lay down bone as an endoskeleton. ‘Living’ bone contains several types of bone cells, marrow, nerves and blood vessels nestled within the inorganic, rocklike matrix. The organic substances in living bone potentially are a concentrated source of nutrients for any carnivore. However, very few animals eat bone because the vast majority of animals can not digest the bone matrix efficiently enough to access the nutrients contained within it.

A few exceptional animals can digest bone, at least partially. Boneworms (of the genus Osedax) digest the bones of marine vertebrates (particularly whales) that have settled on the ocean floor. These deep-sea polychaetes are probably the only animals that are specialised in their lifestyle and in their digestion to feed off bone almost exclusively. Amongst birds, lammergeyers have a diet that consists of up to 90% of bone. These birds can digest bone because they produce incredibly acidic stomach juices (pH < 1!). They also possess a digestive tract that is significantly longer than that of other birds of prey is. Moreover, lammergeyers will glide effortlessly (rather than using flapping flight) even over short distances, thereby reducing energy expenditure. The combination of these adaptations makes a diet of bone feasible for these birds. The large hyaena species will also consume bone regularly; however, this food source never makes up a significant share of their diet.

Detritivores (such as the boneworms) and carnivores (such as lammergeyers and hyaenas) will devour ‘fresh’ bone that is easier to smash or chew and to digest. Their prize for doing this is the nutrient-rich marrow of cells and blood. Why would a giraffe, a vegetarian browser, eat bone?

The habit of animals consuming bones is called osteophagy. Surprisingly perhaps, given the information above, this behaviour is quite common in herbivores. Osteophagy has been observed frequently in domestic animals and wild ungulates (species of deer, camels, giraffes, wildebeest, many other antelope species), as well as in tortoises, and even in some omnivorous bear species. Interestingly, herbivores tend to chew on old, dry bone. Dried out bone (from which bacteria have already removed by decomposition all nutrient-rich cellular material) contains very little energy or nutritional value (although a few fats that have not decomposed fully can still be present even in very ancient bones).

Giraffes are browsers; they feed almost exclusively on leaves of woody vegetation. However, giraffe are seen chewing on bone frequently. It is hypothesised that osteophagy allows giraffes (and other herbivores too) to avoid the costly effects of deficiencies of especially phosphorus and calcium* in their vegetable diet by supplementing their intake of these elements from a different source, namely bone.

Much of the world’s vegetation contains a low (often insufficient) concentration of phosphate. The amount of calcium available to herbivores through their diet is also often limited. The concentration of both of these elements also varies seasonally depending on the amount of rainfall the vegetation receives. The lack of sufficient nutrients in the available vegetation for foraging herbivores is exacerbated in smaller nature reserves because herbivore numbers are often kept high for the continued presence of carnivores in these reserves. Moreover, in small reserves there is little or no scope for even the shortest of local movements by herbivores to other, more nutritious patches of vegetation.

It seems possible that osteophagy has evolved as an innate behaviour in herbivores to gain access to vital nutrients. Several niggling conundrums plague this hypothesis though. There is some evidence, in giraffes at least, that indicates that the digestion of bone material is inadequate to extract phosphate and calcium ions from this source. There is also ample evidence that osteophagy leads to significant, detrimental wear, even breakage, of the dentition of herbivores. Herbivore dentition is adapted to grinding down tough plant fibres – plant material (especially the cellulose cell wall material and any inclusions in it) is much harder to break up physically than animal tissue (‘meat’) is. Through adaptation, herbivore teeth are equipped with many exposed crenulations and ridges of very hard tooth enamel, giving the grinding surfaces of the premolars and molars a rasp-like appearance and function. Yet even small pieces of hard, sun-bleached bone are usually snapped off or broken apart, often with significant wear (even damage) to the teeth of herbivores, and can not be ground down finely enough for the effective digestion of bone material.

I am a trained zoologist – I have known about osteophagy for a long time and I have witnessed this behaviour on several occasions. Nevertheless, on this particular occasion I experienced a strange jolt. I was surprised that the clear and lengthy view of a herbivore licking, sucking and chewing on a bone somehow seemed to be amiss. Deep down my subconscious was signalling that this behaviour was abnormal – cute and cuddly herbivores do not chew on the bones of the dead. No doubt, the antics of the male giraffe, the contortions of the face and neck amplified this slight twinge of unease.

*         Phosphorus and calcium are essential minerals for all animals. Both play a major role in the formation and maintenance of the skeletal system and teeth in vertebrates.

Phosphorus is an essential element in the structure and function of nucleic acids (DNA and RNA), including protein synthesis, cell division and heredity. Moreover, phosphorus is necessary for many biological processes including energy metabolism, cell signalling, and lactation. Phosphate deficiencies can cause physiological side effects, especially pertaining to the reproductive system, as well as side effects of delayed growth and failure to regenerate new bone.

Calcium plays a fundamental role in cell growth and cell division, the transport of molecules across cell membranes, the transfer of information between cells and the transmission of nerve impulses along neurons and across neuromuscular junctions. Calcium is also a vital element required for contraction and relaxation of muscles, the secretion of hormones and the clotting of blood. Calcium ions are involved in a host of intracellular enzymatic reactions too. Prolonged calcium deficiency in young animals may result in rickets, stunted growth and delayed maturity. In adults, a protracted lack of calcium in the diet can lead to fragile bones and osteoporosis, rendering bones prone to fractures. Other symptoms of a calcium deficiency include reduced fertility, lowered milk production in females, paralytic syndromes and a general feeling of lethargy and slowness of action, amongst others.