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LatestPhoto
The eye of an asian elephant. In their respective habitats, sperm whales and elephants appear to have reached the greatest size that mammals can attain on land and in the sea.
Photo: Chris Johnson

April 25, 2003
Sperm Whales and Elephants
  Real Audio Report
  28k


Log Transcript

This is Genevieve Johnson speaking to you from the Odyssey in Sri Lanka.

Having just experienced being with wild elephants at Pinnewala the other day, and with sperm whales in the Gulf of Mannar yesterday, I realize that Sri Lanka is one of only a handful of places in the world where you can spend a day among elephants on land and the next day among sperm whales in the sea.

It is difficult to imagine two mammals with more different habitats, however, there are striking parallels between the lives of these aquatic carnivores and terrestrial herbivores.

Although distantly related, the remarkable size and presumed intelligence of both species seems to result from similar social group behaviors, life histories, and growth patterns.

In their respective habitats, sperm whales and elephants appear to have reached the greatest size that mammals can attain on land and in the sea. But both are not only characterized by extreme body size, both have exceptionally large brains as well as pronounced sexual dimorphism, (the males of both species are bigger than the females).

The brains of sperm whales and elephants weigh approximately five kilograms-three to four times more than the human brain. Whereas the total body weight of mature male elephants is almost double that of the females, a mature male sperm whale may weigh up to five times as much as his female counterpart.

A central feature of both sperm whale and elephant societies is the strongly bonded family unit. Females of both species spend the vast majority of their lives with female relatives and the infant and subadult young of both sexes. Female elephants and sperm whales exist in highly structured female societies, where family members tend to move, feed and rest in each other's company. When threatened, both species are known to defend their offspring and that of related females vigorously, a trait that whalers and poachers used to their advantage by first injuring a calf so that its obvious distress would lure the mother into range.

Lactating female elephants with young calves are frequently found in association with other mother/calf pairs. The babies are grouped together as a 'nursery' unit, with individual adult females taking turns looking after the whole nursery. When a mother sperm whale makes a feeding dive to a depth the calf cannot reach, the mother leaves the calf at the surface with a babysitter.

Both sperm whales and elephants, also share low reproductive rates, exhibit prolonged care of their young, and demonstrate a high degree of cooperation among females. (Whitehead and Weilgart in Mann et al. 2000).

Male elephants and male sperm whales disperse from their natal family groups at an average age of 10 years, the males of both species forming loose aggregations until they reach sexual maturity at an average age of 17 and 20 years respectively, whereupon they start to live pretty much alone in their worlds. From adolescence onwards, male elephants spend the majority of their time away from matriarchal units, though not as far from them as do sperm whales spend their adolescent years.

Only the largest male elephants enter musth, and only the largest male sperm whales seem to make the long trip between their bachelor feeding grounds in polar oceans, and the tropical climes occupied by females and young (Whitehead and Weilgart in Mann et al. 2000).

LatestPhoto
Yesterday, the crew encountered a group of 23 sperm whales off the south coast of Sri Lanka. A central feature of both sperm whale and elephant societies is the strongly bonded family unit.
Photo: Chris Johnson

Thus, the phenomena of 'musth' in elephants and dispersal to high latitudes in sperm whales effectively restrict access to competitive breeding opportunities to older, larger males. (Whitehead and Weilgart in Mann et al. 2000).

Because both species live in environments where they may be invisible to eachother even when but a few body lengths apart (the jungle in the case of elephants; the ocean in the case of whales) both species require something other than vision to keep in touch. Both species appear to use sound for this purpose. Elephants appear to communicate over relatively long distances by means of infrasonic (low frequency) calls; calls in which the main energy is below the range of human hearing. An elephant, when alerted, points its ears forward and turns in the direction of a sound, presumably to catch the sound waves with its large ears. (Katharine Payne 1989). Elephants use these sounds to coordinate group behaviors and as a bond for family units. Sperm whales make regularly spaced clicks while foraging and navigating at depth. However, when socializing, they produce a patterned series of clicks called 'codas'.. As with the infrasound of elephants, it is believed that these codas also serve to coordinate group movements after feeding dives, and to maintain cohesion of the social unit.

Sadly, as is so often found to be the case, the very characteristics that led to the evolutionary success of these species have today left them vulnerable to exploitation by humans. Because whales and elephants both: live long lives in cooperative societies, raise well tended, late maturing offspring, and give birth to single animals at an average interval of five years, their reproductive rates are low and they are not equipped to recover from rapid reductions of their populations. Historically both species have been highly prized for their ivory (although, in the case of sperm whales, the oil was the primary target), a trade that has decimated their numbers. Today sperm whales may face a greater threat from ocean pollution than from whaling, while elephants may face their greatest threat from habitat loss rather than from continued hunting for their tusks.

Throughout ancient history, elephants have played an integral role in the lives of the Sri Lankan peoples, in religious ceremonies and celebrations, and as working animals. As a result, elephants are revered and are protected here. However, it may be that fewer Sri Lankans are familiar with the colossal, warm-blooded leviathans that frequent the deep waters surrounding this island.

However, I know that as Sri Lankans become better acquainted with these equally remarkable creatures, there is little doubt that both whales and people will benefit, and that the whales will be recognized as a priceless part of this remarkable country's rich and diverse heritage.

References:

  • H. Whitehead, & L. Weilgart, 2000. The Sperm whale: Social Females and Roving Males.
    S. Mann, R.C.Conner, R.L. Tyack and H. Whitehead (editors): Cetacean Societies, The University of Chicago Press. 154-173.
  • L. Weilgart, H. Whitehead & K. Payne, 1996. A Colossal Convergence: Sperm Whales and Elephants.
    American Scientist, May-June 1996 v84 n3 p278(10)

Links:

  • Recently, the crew visited the Pinnewala elephant orphanage in Sri Lanka.
  • Sperm Whales are the most social of all the great whales. Click here to learn more.
  • What did the crew of the Odyssey report on one year ago in Australia? Two years ago in Papua New Guinea?
    Three years ago in the Galapagos Islands? -> Real Audio: 28K

    Written by Genevieve Johnson

 
 
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