Sperm whales are the largest toothed cetaceans. Adult females reach about 11 m (36 ft) in length and weigh 15 tons. The males are generally much larger, measuring up to18 m (60 ft) and weighing up to 60 tons. Sperm whales are grayish-brown in color and have a low dorsal fin. Their single blowhole, characteristic of all toothed whales, is located on the left side. Found throughout the world's oceans, sperm whales have some remarkable characteristics, and are able to dive deeper than any other marine mammal. Sperm whales are capable of holding their breaths for up to 90 minutes and can descend as deep as a mile. It is generally believed that they are foraging for squid on these deep dives.

Sperm whales also have very distinctive physical features. Their most noticeable feature is their blunt head, which is typically one third of their entire body length. The head is where the massive spermaceti organ is located. The spermaceti organ is enclosed in a case and filled with spermaceti oil. This oil is of a different composition than the melons of other toothed whales. It is thought that the function of the spermaceti organ is to focus sound produced in the head of the animal. (See How do marine mammals produce sounds?)

Sperm whale vocalizations take the form of directional clicks, from less than 100 Hz to 30 kHz, the majority of energy of which is in the 5 to 25 kHz range. Different click types are used for echolocation as well as for attracting females, repelling males, and maintaining group cohesion. Sperm whales produce repeated patterns of clicks called codas. (See How Marine Mammals Communicate Using Sound - Individual-specific vocalizations)

References
• Goold, J.C. and Jones, S.E. 1995. Time and frequency domain characteristics of sperm whale clicks. Journal of the Acoustical Society of America 98(3): 1279-1291.
• Jaquet, N., Dawson, S. and Douglas, L. 2001. Vocal behavior of male sperm whales: why do they click? Journal of the Acoustical Society of America 109(5): 2254-2259.
• Mohl, B., Wahlberg, M., Madsen, P.T., Miller, L.A. and Surlykke, A. 2000. Sperm whale clicks: Directionality and source level revisited. Journal of the Acoustical Society of America 107(1): 638-648.
• Rendell, L. and Whitehead, H. 2003. Vocal clans in sperm whales (Physeter macrocephalus). Proceedings of the Royal Society of London Series B 270: 225-231.
• Watkins, W.A. 1980. Acoustics and the behavior of sperm whales. pp. 283-290 In: R.-G. Busnel and J.F. Fish (eds.), Animal sonar systems. Plenum, New York. 1135p.
• Cornell Lab of Ornithology, Bioacoustics Program: Sperm Whale Vocalizations

Additional Resources
• Richardson, W.J., Green, C.R. Jr., Malme, C.I., Thomson, D.H. 1995. Marine Mammals and Noise. San Diego, CA: Academic Press.
• Wahlberg, M. 2002. The acoustic behaviour of diving sperm whales observed with a hydrophone array. Journal of Experimental Marine Biology and Ecology 281(1-2): 53-62.
• Zimmer, W.M.X., Johnson, M.P., D'Amico, A., Tyack, P.L. 2003. Combining data from a multisensor tag and passive sonar to determine the diving behavior of a sperm whale. IEEE Journal of Oceanic Engineering 28(1): 13-28.
• PBS Voyage of the Odyssey: The Acoustic Realm of the Sperm Whale
• Whale and Dolphin Conservation Society: Sperm whale