This article is constantly evolving (no pun intended) and is updated almost daily. If you find that you learn something by reading this article, we recommend re-visiting it every now and then to see what else we've added.
Understanding Alpacas as a species
We believe that to better know the physiology of the alpaca it helps to understand the similarities and differences between them, their relatives and other species. By looking at the other species with which they are and are not related, we can better put the alpaca’s individual characteristics into context.
Lets start with where alpacas sit in the species order:
Species Order
Class
Mammalia
(Alpacas are mammals, which, to simplify, means they are warm blooded, Vertebrates, and give birth to live progeny which have been incubated via a placenta)
Order
Artiodactyla
(Alpacas are even toed ungulates)
Suborder
Tylopoda
(Alpacas have padded feet)
Family
Camelidae
(Alpacas are closely related to Camels, Guanaco, Vicuna & Llama)
Alpacas are Ungulates
Alpacas are Ungulates. ‘Ungulates’ describes those mammals that sustain their whole body weight, when moving on their toes. Ungulates are broken into two categories; Odd toed Ungulates and Even Toed Ungulates. The following are all Ungulates: Alpaca, Antelope, Cow, Camel, Deer, Donkey, Gazelle, Giraffe, Goat, Guanaco, Hippopotamus, Horse, Llama, Pig, Rhinocerous, Sheep, Vicuna & Zebra.
Even Toed Ungulates (Artiodactyla)
Even Toed Ungulates (Artiodactyla) are those mammals that bear their weight equally on the third and fourth toes. In contrast Odd Toed Ungulates (Perissodactyla) bear their weight almost entirely on the third toe.
Odd Toed Ungulates (Perissodactyla)
Of the above list of Ungulates, the following are Odd Toed Ungulates (Perissodactyla): Donkey, Horse, Rhinocerous and Zebra.
Characteristics of Ungulates
Most Ungulates have a bone in the ankle called an astragalus or talus that connects the leg to the foot. This talus is typically the bone you see used for the game knuckle bones or jacks.
Another characteristic of Ungulates is the fusion of the front forelimbs. In all ungulates the radius and ulna are fused along the length of the forelimb. This fusion prevents the animal from rotating its forelimb.
Unguligrade, Digitigrade, Plantigrade - How the alpaca walks
When an animal is an 'Ungulate', meaning they support the weight of their body on their toes - Most Ungulates support the whole weight of their body on the 'tips' of their toes. The term to describe the way they walk when they support their weight on the 'tips' of their toes is Unguligrade.
Alpacas, and all Camelids, despite being referred to as an Ungulate, are Digitigrade. To understand what this means for alpaca anatomy and how it differs from other animals, maybe we could start with a human foot as an example. In contrast to Unguligrade and Digitigrade, Humans are Plantigrade. Plantigrade means we place the full length of our foot on the ground during each step or stride that we make.
This diagram below shows a human foot from above with our 5 toes made up of groups of phalanges (2 for the big toe, and 3 each for the 2nd, 3rd, 4th and 5th toes). These toes are at the end of the 5 Metatarsals.
This diagram shows the human 'plantigrade' habit:
It is believed that alpacas became Digitigrade overtime due to the need to increase their ability to out-run predators.
There are two ways for an animal to become faster, one is to increase their stride length and one is to increase the stride rate.
Running on the tips of your toes is one way to increase stride length.
This picture shows another digitigrade animal (a cat):
Digitigrade means that an animal stands or walks on its digits (or toes). A digitigrade animal is generally faster and more quiet then an animal that is Plantigrade. Compare this to the picture of the human foot and note where we would be placing our weight if we were Digitigrade.
The next stage up from Digitigrade, is of course, Unguligrade. Again Ungulates are those animals that walk on the 'tips' of their toes thus enabling them to increase their stride as much as possible.
This is a picture of a deer's foot which is unguligrade:
Again if you compare this to the Human foot and the Cat foot and consider balancing our weight on the tips of our toes. Interestingly Camelids in history were nearly Unguligrade. In otherwords they evolved to be somewhere between Digitigrade and Unguligrade, and they probably had hoofs. This was in a time in history called the Oligocene and the early Miocene. At this time the cannon bone was completely or nearly completely fused.
Cannon Bone
Lets have a look at what a Cannon bone is:
Another way to increase an animals stride is to lengthen the limbs. Alpacas and some other Ungulates have done this by lengthening the metatarsals in their feet for their hindlimbs and the metacarpals in their feet for their forelimbs. Again lets look at the human foot picture to remember what are the metatarsals:
For clarification the bones that are lengthened in the feet of the forelimbs are the Metacarpals which corresponde with a Human Hand rather than a Human foot. Here is a diagram of a Human Hand, showing the Metacarpals and Phalanges and you can see the obvious similarity to the Metatarsals and Phalanges in the Human foot.
We will only refer to Metatarsals and feet from now on for ease of dialogue, but it is important to realise that the bones in the forelimbs are named differently.
When a metatarsal is lengthened it can be broken more easily, so some ungulates have through evolution compensated for this by fusing metatarsals together which restores strength to a now longer foot bone. Often when animals, through an evolutionary process, elongate their metatarsals, they also reduce the number of metatarsals that they have.
Look at this picture of a deer's foot front on showing the fused 3rd and 4th metatarsals, which once fused are now called a Canon Bone:
You can see that the deer foot has really only got the 3rd and 4th metatarsals and it has fused them together to make a longer, stronger foot bone.
Very similar to the deer is the fusion of the metatarsals in Camelids, however Camelids only fuse the 3rd and 4th metatarsals together, 'partway' down the bone. Then these two metatarsals branch out forming a 'Y' shape. This picture illustrates that:
So the ancestors of Camelids in history were nearly Unguligrade and their Cannon Bone was either completely or nearly completely fused much like what you can see on the deer's foot. It is also believed that at this point early in the Miocene that they had hooves. Then in the Miocene and the Pliocene the ends of the Cannon Bone seperated, giving Camelids their splayed toes, and they at this point returned to a Digitigrade stance.
But why? - The theory is that the evolutionary process that took them to a near Unguligrade stance, (likely in order to out run predators) coincided with the evolutionary process that gave them their pacing gait. One disadvantage of the Camelid's pacing gait is a lack of, or a reduction in lateral stability. Research indicates that this became an issue prior to the spread of Grasses during the Eocene and therefore when the ground was still, for the most part, soft and sandy. The return to a digitigrade stance and the splaying of the Cannon Bone and therefore the splayed toes, along with the large soft pads on the bottom of their toes (which gives them the name Tylopoda) appears to be an adaptation at that time to enable Camelids to pace long distances over sandy and soft soils, with speed and also with stability.
The South American Camelid (SAC) being the Alpaca, Vicuna, Llama, Guanaco adapted the ability to move the pads on their toes as the habitat that they occupied included steep & rocky terrain.
The alpacas foot and pastern as a result of evolution
Lets have a look at an Alpaca's foot now we understand it has a modified digitigrade stance, two toes, and a soft pad on the bottom.
This is the bottom of an alpaca's foot showing the two toes, the soft pad which bears the weight of the alpaca and a couple of long toenails. The alpaca is about to get his toenails trimmed.
This picture shows all four legs of an alpaca, and the splayed two toed feet with toenails.
This is a close up of the alpaca foot front on
It can be hard to see where the pastern finishes and the canon bone begins sometimes, but it is an important aspect of alpaca conformation. Have a look at this diagram to remember exactly where the pastern (or proximal phalanges are).
This link will take you to a page on Llama conformation, if you scroll down the page you will see some examples of Llamas with dropped or weak pasterns.
Breed Standards
The Alpaca Association of New Zealand (AANZ) describes in its breed standards under legs: "The forelegs are strong and straight. The hindlegs are straight and parallel when viewed from behind. The pasterns are firm and upright. The feet are neat and well formed and bear two forward pointing toes each carrying a long strong toenail. The sole of the foot is covered with a callused membrane. - Faults: Weak Pasterns, Obvious Carpal Deviation, Cow Hocks, Sickle Hocks".
The Australian Alpaca Association (AAA) Breed Standards also bear this statement.
References to weak Pasterns
This link to a small article under Physical Maturity on Lost Creek Llama's website, gives some insight into pastern problems and is worth a quick read in reference to what sort of influence pasterns have on Llamas and alpaca's conformation, and anatomy, and likewise how excess weight can have an impact on the pasterns.
Treatment for pastern problems
We have found these pages on the net regarding treatment and support for alpacas and llamas with weak pasterns. We have not used either treatments and therefore can not endorse them, but if you are in need of information these pages may be a good start in your search.
This is a link to cria-bee supports, which are like support bandages, (similar to perhaps a material knee brace that people wear), for premature cria who are low or dropped in the pasterns, to help get them up and walking, and I guess strengthening the pasterns.
This is a link to Llama Doc Herbs, we found the brief article on this site interesting and consider it food for thought should we encounter any problems with our stock, when you go to his page click on the 'Tendon Repair' link and after a quick look at that click on the 'read more' link.
As always your first point of call should by your vet.
Artiodactyla (Even Toed Ungulates) - What distinguishes the Alpaca from the rest?
Now let’s look at the Even Toed Ungulates (Artiodactyla) a bit more closely.
The following groups make up the Order Artiodatyla:
Suina (Pig Family)
Tylopoda (Camel Family)
Ruminantia (Goats/Cattle Family)
Of the 3 groups, all are quite different:
Suina in general have simpler stomachs, they have 4 toes, short legs and their teeth are different; such as smaller molars and canine teeth that are often in the form of tusks. Some are Omnivores which mean they also eat meat.
Camelids & Ruminantia in comparison to Suina have longer legs, complex cheek teeth which they use to grind up coarse grasses, and a digestive process that is highly developed.
Suborder: Tylopoda
(Padded Foot)
Family – Camelidae: Camels, Guanaco, Vicuna, Llama, Alpaca
The Tylopoda which means ‘Padded Foot’, makes up the Camel Family that alpacas belong to and 'quite rightly', sits between Suina and Ruminantia. Tylopoda have some characteristics which are similar to Suina and Ruminantia but they stand out in that they have some special modifications not shown in the other two groups.
Digestive Systems
All Ruminantia are ruminants, which means they digest their food in two steps: Chewing and swallowing and then regurgitating what they have swallowed. The regurgitated food is known as the cud. The cud is then chewed again, which is called ruminating. They do this in order to get the most nutrition from the food as possible.
Camelidae (Camels, Guanaco, Vicuna, Llama and Alpacas) are also ruminants but do not belong to the Ruminantia. It has been suggested that they developed their ruminant ability separately from that of the Ruminantia.
Camelidae are different from other Ruminants in many ways, and most importantly have only a three chambered digestive tract, rather than the 4 chambers that members of the Ruminantia have.
Odd Toed Ungulates (Perissodactyla) (Donkey, Horse, Rhinocerous, Zebra) in contrast to the Camelids are hindgut fermenters; that is, they digest food in their intestines rather than their stomach. Hindgut fermenters store digested food which has left the stomach in an extension of the small intestines called the caecum, where the food is attacked by gut bacteria.
It pays now to go back into history for a moment.
Around about 46 Million years ago during a period called the ‘Eocene’, Odd Toed Ungulates (ancestors and relations of the Donkey, Horse, Rhinocerous and Zebra) were a dominate terrestrial herbivore, which basically means they dominated the Eco Systems that they occupied. In turn the Even Toed Ungulates were not dominant and they survived only in marginal habitats. Because the habitats that Even Toed Ungulates were forced to occupy had lower grade feed available, it is presumed that it is at this point in history they developed their complex digestive systems, in order to get as much nutrition as possible from their feed.
During this Eocene period, climatic change saw the appearance of grasses, which had not previously existed. About 20 Million years ago in a time called the Miocene, these grasses then spread and were commonly available. Because these grasses were coarse and made up of low nutrition, they were not easy to digest. However as the Even Toed Ungulates (Artiodactyla) had developed their complex digestive systems, they came in to their own and over the course of millions of years, many odd toed ungulate (Perissodactyla) species went extinct. This extinction was partly due to climatic change, the introduction of the grasses which were difficult to digest and the new competition from other herbivores such as the Even Toed Ungulates (Artiodactyls).
This starts to give us some insight into how and why Alpacas and their close relations have been able to survive in the Plantel in South America, and why their digestive systems have evolved to what they are today.
Camelids 1st appeared around 45 million years ago, late into the Eocene period, in North America. 2-3 million years ago after the Isthmus of Panama was formed, some camelids moved into Asia. The original North American Camelids then disappeared (Became Extinct).
Once the North American Camelids were gone this left only 3 species behind, the Dromedary of Northern Africa, and South West Asia, The Bactrian Camel of Eastern Asia; and the South American Camelid which includes Llamas, Alpaca, Guanaco and Vicuna.
Nanobodies - Can Alpacas cure cancer?
A feature which is unique to Camelids among all mammals is that they have elliptical red blood cells and a special type of antibodies lacking the light chain in addition to the normal antibodies found in other species. From this different antibody is being developed nanobodies, which scientists believe can help with the treatment of cancer. See these links for more information on Nanobodies: (its quite technical in places)
