Artiodactyla is an order of placental mammals composed of even-toed ungulates—hooved animals which bear weight equally on two of their five toes with the other toes either present, absent, vestigial, or pointing posteriorly—as well as their descendants, the aquatic cetaceans. Members of this order are called artiodactyls. The order is sometimes named Cetartiodactyla, in reference to the inclusion of cetaceans in the order beginning in the 1990s. Artiodactyla currently comprises 348 extant species, which are grouped into 131 genera. Artiodactyls live on every major landmass and throughout the oceans and in a variety of habitats, including forests, grasslands, and deserts. They come in a wide array of body plans in contrasting shapes and sizes, ranging from the 38 cm (15 in) long and 2.5 kg