Hippos
Hippos probably evolved from a common ancestor for whales. The separation of this line was about 54 million years ago, then it began to evolve in one part of the Anthracotheriidae, the family of four-legged animals, of which one branch has evolved further in the direction hipopotamowatych. Another common ancestor of the family was żyjący Anthracotheriidae about 20 million years ago Libycosaurus, it was more closely related to hippos. The oldest hippo was the subject of family Kenyapotamus coming from Africa against 16-8 million years ago. The ancestor of the current hippo was Archaeopotamus żyjący of 7,5-1,8 million years ago in areas of the current Middle East and Africa.

Characteristics

Height at shoulder 1.5 m
Length 3,5-5 m
Weight 1500-1800 kg males up to 3000 kg
                                      1300-1500 kg females

Occurrence, habitat: Africa, mainly in the south of the Sahara. They live in areas where there are rivers and lakes are in areas up to 2000 m asl

Evolution: the animals adapted to live both in water and on land. With high-placed eyes and nostrils and ears, hippos may be almost completely submerged in water. The skin is thick at 4 cm, provides up to 25% of the entire animal. It has protection from the sun in the form of a special secretion of reddish color, consisting of pigment in the form of acidic compounds. Although compact, rugged construction hippos can run at speeds of up to 50 km / h, but only at very short distances. In the water reaches the speed of 8 km / h Hippos can be steeped for 4-6 minutes, after which time they emerge for air. This process is carried out automatically, even during sleep.

Lifestyle: Hippos live in herds, but this does not look to create their social ties. The exception is the relationship between older and younger females. Territory is only hippos in the water, where he sexually grouped in each group is male dominant, while others are subordinate. For most of hippos lying down in the water. Individual landfall is to feed plants in the evening and night.

Diet: Mainly grass, and sometimes other small plants. Very few are the cases of predation and cannibalism. Food intake by the hippo takes ok5 hours a day, can eat FOR IN-hour to 70 kg of food.

Reproduction: gestation lasts 8 months. Young are born in water, usually one piece at a birth, weigh 25-45 pounds and have a length of more than 1 m

Development: Young animals benefit from breast milk from 6-8 months of age, and stop eating them after about a year. Most of the time staying with their mother, often lying on her back. Females reach sexual maturity at the age of about 5 years, males aged 3-4 years.

The threat of animal: Hippos exhibit aggressive behavior, especially the crocodiles of the same bodies of water, but also towards each other in territorial disputes, often killing each other. There are also cases of attacks on humans.

Security: Due to the decline in hippo populations has been recognized as endangered and listed in 2006 in the Red Book of Threatened Species created by the IUCN. Threats to these animals are mainly associated with cases of poaching.