Pigs

ENVIRONMENT

“ wet mud keeps them cool as heat is given off by evaporation – a technique also used by elephants”

Anatomy of the pig

Often maligned in popular culture and language, hogs are much smarter and cleaner than you might at first think… Piggy physiology

What is special about the anatomical make up of the pig?

Tail

A pig’s short tail can comprise over 20 caudal vertebrae, which is around the same number found in a cow’s tail.

It seems unfair that the English language has amassed so many derogatory sayings about pigs, because under the skin they’re a lot like us. Indeed, the hearts of some breeds are similar enough in weight, internal structure and the rate at which blood is pumped through to have potential for human heart transplants. Pigs are also impressive learners. In a study published in 2009 scientists showed a reflection of food to pigs who had previously seen mirrors and compared their responses with a group that hadn’t. The former were much less likely to think the food was behind the glass.

Pigs and other members of the Suidae family, which includes wild boars and warthogs, have a strong skeleton that allows them to be sturdy defenders of their territories and offspring. They also have a very good sense of smell that compensates for poor eyesight. A hog’s snout, together with its even-toed trotters and short, muscular limbs, is perfectly adapted for sniffing out and uncovering food buried in the soil of the forests and grasslands in which the species evolved.

Wild pigs will consume grubs, amphibians and small birds as well as forage for roots, leaves, nuts, fruit and fungi. To chew on this omnivorous diet they have canine, incisor and molar teeth, just as we do. The pig’s digestive system, meanwhile, features anatomical differences from ours (a spiral colon, for example), but works the same way: food is broken down in a one-chambered stomach and intestines and then passes through to the colon for excretion.

Contrary to the myth, pigs keep bodily waste away from food and don’t wallow in it. They do like a mud bath because they don’t perspire. Wet mud keeps them cool as heat is given off by evaporation – a technique also used by elephants. ‘Sweating like a pig’ then is one saying that definitely does pigs a disservice.

Leg

Strong legs allow piglets to stand soon after birth. As adults they use that strength to dig for food.

Intestines

The cecum and colon that make up the large intestine in pigs are arranged in spiral coils.

dId YoU kNoW?

Extinct entelodonts might be nicknamed ‘hell pigs’ but are only distantly related to modern porkers

Spine

Projections on the strong lumbar vertebrae broaden the abdomen and are attached to muscles that support the internal organs.

Skin

Although the structure of a pig’s skin is similar to our own, they have very few sweat glands. To cool down they bathe in mud; this also serves as a kind of sunscreen.

pork’s unwanted passengers

Once you realise what might be lurking inside your pork chops you might be inclined to turn up your oven. Pigs can be infected by common roundworms in the genus Trichinella. Transmission to humans can occur through eating meat that isn’t cooked at a high enough temperature to kill the larvae. Ingestion results in trichinosis, with symptoms including dizziness and stomach ache. Among pig parasites, though, pork tapeworm (Taenia solium) is more concerning.

The larvae of this tapeworm also enter the human body through undercooked meat. Once inside, they migrate to the tissues, causing cysticercosis. The symptoms can be minor if they infect only muscles, but can include loss of vision or weakness if larvae reach the eyes or the spine. The infection can be more serious still if worms reach the brain and form cysts, causing neurocysticercosis; in these cases, victims can fall into a coma or even die suddenly.

Tapeworms are nasty parasites that set up home in the intestines

ear

Pigs’ ears pick up a wider range of frequencies than human ones and are good at locating where sounds originated.

Stomach

A pig’s stomach includes a torus pyloricus, a muscular sphincter also found in the stomachs of herbivorous ruminants such as cattle.

Trotter

Pigs are even-toed ungulates, which means their weight is carried on the third and fourth toes of their cloven hooves.

Heart

Differences between pig hearts and those of humans include two pulmonary veins entering the left atrium instead of four.

oesophagus

As in humans, the pig’s oesophagus channels food to the stomach using muscular contractions in a process called peristalsis.

Snout

Consisting of a cartilage disc protected by a prenasal bone, a pig’s nose is both a digging aid and sniffing tool.

truth about truffles

Sows have long been associated with truffle hunting. Yet it isn’t clear what makes them good at rooting out the subterranean fruiting bodies of these fungi. Truffles have a distinctive smell, but pigs must be attracted by more than just appreciation of the aroma.

For many years the prospect of sex was thought to tempt them. That’s because some truffle species produce androstenol, a pheromone-like hormone found in the testes of boars (as well as humans). That theory, however, was undermined by French chemist Thierry Talou. He buried samples of androstenol, fresh truffles and a synthetic cocktail of aroma-causing chemicals and let some sows loose. Surprisingly, the pigs skipped the androstenol and went for the other two options. Whatever it is that attracts sows, though, is too strong for them to resist. Many truffle-hunters have replaced pigs with trained dogs that don’t eagerly gobble up the fungal delicacies they find.