The pigs who are they?

Dr John Carr


The pig is a fascinating mammal, which as a group is extremely widespread over the planet.  The pig has been able to adapt to all climates below the snow line.  With the advent of human farming, one species – Sus scrofa has become worldwide including inhabiting above the snow line.  The pig is present on all continents excluding Antarctica.  The domestic/wild boar is a fairly basic mammal, it has retained almost all of the basic mammalian characteristics and therefore, are extremely adaptable to changes in the environment.

The evolutionary relationship between different pig species


Mammals in general

Pigs and other even toed mammals


Global distribution of species of the suborder Suina and Hippopotamidae


Suina worldwide


American Peccaries

African Pigs and Hippos

Eurasian Pigs

Island Pigs

Catagonus wagneri

Hylochoerus meinertzhageni

Sus salvanius

Babyrousa babyrussa

Tayassu pecari

Phaeochoerus aethiopicus

Sus scrofa

Sus barbatus

Pecari tajacu

Phaeochoerus africanus


Sus cebrifrons

 Pecari maximus

Potamochoerus larvatus


Sus celebensis


Potamochoerus porcus


Sus phillippensis


Hippopotamus amphibious


Sus verrucosus


Hexaorotodon liberiensis


Sus bucculentus


Where did they come from?















evol Dichobunidae





evol Archerotherium











(Babyrousa babyrussa)


Wart Hog – (Phacochoerus africanus and Phacochoerus aethiopicus)



European wild boar (Sus scrofa)

Variety of island pig species

Bearded pig (Sus barbatus)

Pigmy pig (Sus salvanius)


Bush pig (Potamochoerus larvatus)

Red river hog (Potamochoerus porcus)


Giant forest Hog (Hylochoerus meinertzhageni)


Differences between the groups



Upper canines may measure 230 mm  The lower canines may reach a length of 700 mm, of which 300 mm is above the gum line and they can weigh as much as 300g.   The mouth can open to 150°

Nostrils are carried on top of the snout.  The nostrils can be closed.  The eyes are set high up and protrude. 

Skin contains special glands that secrete a pinkish substance known as “blood sweat”  Skin contains a large amount of fat.  The skin must remain moist or it will crack. In the Pigmy  hippo the  body is without hair, except for a few bristles on the lips and tail

The foot bones are separate and all toes support weight.  The terminal digital bones have nail-like hooves. 

Stomach is complex with three chambers, but it is non-ruminating.

Hippopotamus amphibius

(I 2-3/2-3, c1/1, pm 4/4 m 3/3) x 2 = 40-42


Seasonally polyoestrus.  In some areas there are peaks in breeding with births occurring at times of maximum rainfall.

Interval between births often 2 years

Oestrus lasts 3 days.

Gestation: 227- 240 days

Head and body length 290 – 505 cm

Shoulder height 150 – 165 cm


Males are larger on average

1,000 to 4,500 kg

Hexaorotodon liberiensis

(I 2-3/1, c1/1, pm 4/4 m 3/3) x 2 = 38-40

Oestrus: 28 days lasting 2-3 days

Gestation: 184-204 days

Head and body length 1,500 – 1,750 mm

Shoulder height 700 – 1,000 mm


160-270 kg



Upper canines form tusks, directed downwards not outwards or upwards as in Suidae, and they are generally shorter.  Tusks are more slender.

Tusks average length is 40 mm.  There is a space between the canines and premolars  The premolars increase in size to first to last.   The molars have square crowns with four cusps  The molars are high crowned (hypsodont) rather than low crowned (bunodont).

Legs are long and slim and the hooves are small.  There are four digits on the forefoot, the two lateral ones being reduced and do not touch the ground.  There are two functional digits on the hind foot.   There is a vestigial median digit on the back of the hind foot in Pecari and Tayassu but not in Catagonus.  The third and fourth foot bones are united at their proximal ends (as in ruminants – but not suids).  Elongated snout, longer than other peccaries  Tails have reduced number of vertebrae - 6-9.

Scent gland 75 mm in diameter and 125 mm thick on the rump in front of the tail.   Emits a specific odour.  Hair can be made erectile when excited.

The stomach is two chambered but more complex than in suids but none ruminating.  

Milk is lower in fat than Suidae    2 pairs of mammae

The Pecarri tajacu  is gregarious – group size of 2 to 50 but usually 5 to 15, with groups of both sexes and all ages. Several groups or sounders may group together.   Tayassu pecari may occur in large groups or herds of up to several hundred animals.  Hierarchy is present, dominant animal male

Catagonius wagneri

(i 2/3, c 1/1, pm 3/3, m 3/3) x 2 = 38


Mating occurs in April and May with the young being born in August and September (early spring)

Litter size 1-4, usually 2-3

Head and body length of about 900 – 1,112 mm

Shoulder height 520 – 690 mm


29.5 – 40 kg

Pecari tajacu

Oestrus Average 24 days and oestrus lasts 4 days

Gestation round 145 days

Litter size 1-4, usually 2.

Head and body 750 – 1,000 mm

Shoulder height 440 – 500 mm


14-30 kg



Tayassu pecari

Gestation: 156 – 162 days

Head and body length 900 – 1,300 mm

Shoulder height 440 – 600 mm

20-50 kg

Pecari maximus

120-137 length

40-50 kg


Babyrousa babyrussa

(i 2/3, c 1/1, pm 2/2, m 3/3) x 2 = 34

Early months of the year.   Can produce two litters per year

Oestrus:28-42 days with oestrus of 2-3 days

Gestation: 155 to 158 days

Litter size 1-2

Head and body length 875-1065 mm

Shoulder height is 650-800 mm

Upper incisors curve upwards and pierce the nasal skin.

The snout is grooved

Only two pairs of mammae.  Biloped stomach.

Wart Hog

3rd Molar composed on set of cylinders of dentine set in cement.  No upper incisors in P. aethiopicus

Warts are prominent only on the males, are skin growths and has no bony support or core.  They are located on the side of the head and in front of the eye.  

Phacochoerus africanus


Phacochoerus aethiopicus

P. africanus: (i1/3, c1/1, pm 3/2, m 3/3) x 2 = 34


P. aethiopicus (i0/3-0, c1/1, pm 3/2, m 3/3) x 2 = 32-26   


Females are polyoestrus, oestrus lasting about 72 hours at intervals of 6 weeks.

Gestation: 150 – 175 days

Head and body length 900-1500 mm

Shoulder height is 635 – 850 mm


Weight is 50 -150 kg

Red River Hog and the African Bush Pig

Upper tusk 76 mm – point downwards and wear against the lower ones.  Lower tusk 165-90 mm. 

Male has warts in front of the eye,  which although they protrude 40 mm, frequently are not conspicuous as they are concealed by facial hair.

 9-15 individuals in a sounder. May travel in up to 60 individuals.  The immature to adult ratio is generally 2:1

Potamochoerus porcus


Potamochoerus larvatus

(i 3/3; c 1/1; pm 4/4; m 3/3) x 2 = 44

(full mammalian dention)


Gestation: 120 days

Head and body length – 1,000 to 1,500 mm

Shoulder height 585 - 965 mm

Weight is 46-130 kg

Giant Forest Hog

Large skull contains a large depression in the roof.  The nose is very prominent  Preorbital gland is present, marked externally by a slit on the naked area of the face in front of each eye.

Hylochoerus meinertzhageni

( i 3/3, c 1/1, pm 4/4, m 3/3) x 2 = 44

Canines are set horizonally.

Breeding is continous.  Mating peaks in East Africa in the latter part of the rainy season.

Gestation: 151 days

1,300 to 2,100 mm long.  Shoulder height is 762 – 1,100 mm.



Oesphageal diverticulum.  Pyloric torus – bile duct close to stomach.  Preputial diverticulum.  Carpal glands.  Testes upside down.  Lymph nodes reversed anatomy.  Multipapillary kidney.  Piglets born with 8 needle teeth.  Some of these features may be in other suina.  Hippopotomus lymphnodes have similar lymphoid anatomy. Sus scrofra, Sus salvanius – no warts.  Other species of Sus have warts – often 3 pairs

Sus scrofa


( i 3/3, c 1/1, pm 4/4, m 3/3) x 2 – 44

The canines in males the inferior surface is narrower than the posterior surface.  The female canines are small versions of the male.

Breeding occurs throughout the year in the tropics, birth peaks shortly before or just after the rains.  In the temperate regions the young are born in the spring.

Oestrus 18-24 days

Gestation: 112 – 120 days

Litter size: 6-12 up to 40 domestic breeds


900 – 1,800 mm.  Shoulder height 550 – 1,100 mm


40-350 kg

40-350 kg

Sus barbatus

Sus bucculentus

Sus cebifrons 

Sus celebensis

Sus philippensis

Sus verrucosus

Sus salvanius

500-710 mm. Shoulder height 250-300 mm.  .

6.6 to 9.7 kg