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

Global distribution of species of the suborder Suina

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
	Potamochoerus larvatus		Sus celebensis
	Potamochoerus porcus		Sus phillippensis
	Hippopotamus amphibious		Sus verrucosus
	Hexaorotodon liberiensis		Sus bucculentus

Where did they come from?

Kingdom	Animalia
Phylum	Chordata
Class	Mammalia
Order	Artiodactyla
Suborder	Suina
Eocene	Family		Dichobunidae
	Family		Entelodontidae
			Archaeotherium
Modern	Family		Hippopotamdae
	Family		Tayassuidae
	Family:		Suidae:
		Genus: Babyrousa		(Babyrousa babyrussa)
		Phacohoerus		Wart Hog – (Phacochoerus africanus and Phacochoerus aethiopicus)
		Sus		European wild boar (Sus scrofa)
				Variety of island pig species
				Bearded pig (Sus barbatus)
				Pigmy pig (Sus salvanius)
		Potomochoerus		Bush pig (Potamochoerus larvatus) Red river hog (Potamochoerus porcus)
		Hylochoerus		Giant forest Hog (Hylochoerus meinertzhageni)

Differences between the groups

Hippopotamus
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
Peccary
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
Babyrousa
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
3^rd 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.
Suidae
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