Hippopotamus

 

Scientific name

Hippopotamus amphibius

Global distribution

Throughout Africa south of the Sahara.  However, erosion of its territory is fragmenting the animal’s range.

Habitat

Deep permanent water with adjacent reedbeds and grasslands.

Conservation status

Appendix 2 CITES.

Physical characteristics

Body size

male

Head and body length 290 – 505 cm

Shoulder height 150 – 165 cm

Males are larger on average

Weight

1,000 to 4,500 kg

Colouring

Usual colour of the skin is a slaty copper brown, with shades to dark brown above and purplish below

Hair

The body is scantily covered with short fine hairs that appear naked.

Piglet colouring

Skin that is slat grey

Tail

Short triangular

40 – 56 cm

Male side view

Face view

Rear view

Note short triangular tail

No apparent scrotum in the male

Female side view

Face view

Rear view

Drinking pattern in Portugal Zoo

Anatomical points

Peculiarities

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.

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.

Track of a hippo

Note weight on all four digits and heel pad

 Fore limb digits detail

Hind limb digits detail

Plantar surface of the hind foot.

Glands

Skin glands produce ‘blood sweat’

Dental formulae

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

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°.

 

Skull face view

Skeleton side view

Behaviour points

Maturing age

In captivity 3-4 years.
Males in the wild about 6-13 years of age

Females in the wild about 7-15 years

Mating ritual

 

Dominance ritual

Bulls which do not back down easily, will approach each other with mouths jaws, scoop water up into their mouths and spray it high in the air.  Usually there is no contact, but sometimes the lower jaws are slammed together and serious fights will develop.

Seasonal breeding

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 period

Lasts 3 days.

Gestation period

227- 240 days

Litter size and lactation

Single occasionally twin calves.

Birth weight of 25-55 kg

Lactation

Weaning at 6-8 months

Weaning age

6 to 8 months

Family groups

May live alone or in large groups of up to 150 individuals.  Normally 10-15 are found in a group.  Most of the group will be female.

Groups may be dominated by a bull male.

Territories may be marked by defecation piles.

Cooling behaviour

The Hippopotamus spends most of the day in water

   

Hippos in the water

Hippos below water

Peak activity

 

 

While the hippopotamus is amphibious, it is actually a poor swimmer.

Normally only stays submerged for 1-3 minutes but can stay submerged for 30 minutes at a time.

Buoyancy is such that the Hippopotamus can walk around on the body of the river

Range

The Hippopotamus may travel over 33 km a night in water in search for food

Grazing range may extend 3.2 km from the water

Population density can be very high locally, reaching 19.2 sq km.

Senses

Hearing, sight and smell are all well developed.

Diet

Mainly grass and vegetation, cropped by the action of the horny lips

It requires about 1-1.5% of its body weight for maintenance.  Its metabolic rate is relatively low.  The Hippopotamus spends about 5-6 hours a day grazing.  In a single night it can eat about 100 kg of water plants and destroy almost the same amount by standing on it.

Diseases/

disorders

 

Age

In the wild about 41 years.  In captivity 61 years.