<p><span class="taxon"><em>Hylobates syndactylus</em></span> is the largest of the gibbons, weighing between 10 and 12 kg. The head-body length ranges from 71 to 90 cm. They have a thick, black fur coat and long, slender arms. The arm length may attain 2.3 to 2.6 times the body length. Both sexes have long canine teeth, opposable thumbs, and a great toe that is deeply separated from the foot. <span class="taxon"><em>Hylobates syndactylus</em></span> has a short-muzzled face that is nearly hairless, accompanied by a large brain case.</p> <p>The most distinguishing characteristic of siamangs is the enlarged throat sac that can be as big as a human head! These throat sacs are used as a sound box to amplify their loud vocalizations.</p> <p>Siamangs are syndactylous, having their 2nd and 3rd toes fused by a thin webbing of skin.</p> <p>(Preuschoft, 1990; Chivers, 1979)<span> (Nowak, 1999)</span></p> <p><strong>Other Physical Features: </strong>Endothermic; Homoiothermic; Bilateral symmetry</p><p><strong>Sexual Dimorphism: </strong>Sexes alike</p>
- Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.