An elephant's trunk has up to 150,000 muscle bundles and no bone
The largest land animals descend from a creature weighing just 3 to 8 kilograms that lived in Africa 60 million years ago. Today's elephants pick up food with a boneless trunk of up to 150,000 muscle bundles, cool themselves by flapping blood-filled ears and talk across long distances with sounds too low for us to hear.
Three species survive: the African bush elephant, the African forest elephant and the Asian elephant, the last members of the order Proboscidea, which once included mammoths and mastodons. Molecular work confirmed the two African forms are separate species, and showed mammoths were closer to Asian elephants than to African ones. Surprisingly, their nearest living relatives are manatees, dugongs and the small rabbit-like hyraxes.
Proboscidean history began with Eritherium in Paleocene Africa, a tiny animal by comparison. By the late Eocene, Barytherium weighed about 2 tonnes, while Moeritherium may have lived partly in water. When Afro-Arabia collided with Eurasia about 18 to 19 million years ago, the group spread out of Africa. True elephants emerged later from gomphotheres, with ridged molars suited to grinding grass.
The body is a set of engineering solutions. The trunk fuses nose and upper lip and grips objects precisely. Tusks are enlarged incisors used for digging, lifting and fighting. Ear flaps only 1 to 2 millimetres thick in the middle are packed with capillaries that shed heat, helping hold body temperature near 36 °C. Having no tear ducts, elephants keep their eyes moist with another gland. African elephants have bigger ears and dipped backs; Asian elephants smaller ears and flat or arched backs.
Socially, females live in family groups led by the oldest cow, the matriarch, which merge and split in a fission-fusion society. Males leave at puberty and during musth show surging testosterone and aggression. Calves depend on their mothers for up to three years, and wild elephants can live to 70. They communicate through touch, smell, sight, and infrasound and vibrations through the ground; they appear self-aware and may show concern for their dead. Bush and Asian elephants are endangered and forest elephants critically endangered, threatened chiefly by poaching for ivory, habitat loss and conflict with people.
Source: Elephant
