The animal on the cover of Hadoop: The Definitive Guide is an African elephant. Thesemembers of the genus Loxodonta are the largest land animals on earth (slightly largerthan their cousin, the Asian elephant) and can be identified by their ears, which havebeen said to look somewhat like the continent of Asia. Males stand 12 feet tall at theshoulder and weigh 12,000 pounds, but they can get as big as 15,000 pounds, whereasfemales stand 10 feet tall and weigh 8,000–11,000 pounds. Even young elephants arevery large: at birth, they already weigh approximately 200 pounds and stand about 3feet tall.

African elephants live throughout sub-Saharan Africa. Most of the continent’s elephantslive on savannas and in dry woodlands. In some regions, they can be found indesert areas; in others, they are found in mountains.

The species plays an important role in the forest and savanna ecosystems in which theylive. Many plant species are dependent on passing through an elephant’s digestive tractbefore they can germinate; it is estimated that at least a third of tree species in westAfrican forests rely on elephants in this way. Elephants grazing on vegetation also affectthe structure of habitats and influence bush fire patterns. For example, under naturalconditions, elephants make gaps through the rainforest, enabling the sunlight to enter,which allows the growth of various plant species. This, in turn, facilitates more abundanceand more diversity of smaller animals. As a result of the influence elephants haveover many plants and animals, they are often referred to as a keystone species becausethey are vital to the long-term survival of the ecosystems in which they live.

The cover image is from the Dover Pictorial Archive. The cover font is Adobe ITCGaramond. The text font is Linotype Birka; the heading font is Adobe Myriad Condensed;and the code font is LucasFont’s TheSansMonoCondensed.