Mesoplodon layardii

Geographic Range

Mesoplodon layardii tends to live in the cold temperate waters of the Southern Hemisphere. A majority of the sightings have been around Australia, New Zealand, and Tasmania, but there have also been sightings in South Africa, Namibia, the Falkland Islands, Argentina, Chile, and Uruguay.

• Biogeographic Regions
• indian ocean
  • native native
• atlantic ocean atlantic ocean
  • native native
• pacific ocean pacific ocean
  • native native

Habitat

Strap-toothed whales are found in deep oceanic waters of the temperate to subantartic regions. They may use adjacent waters for feeding and calving.

• Habitat Regions
• saltwater or marine saltwater or marine

• Aquatic Biomes
• pelagic pelagic

Physical Description

Adult strap-toothed whales weigh between 907 and 2,721 kg and are 5 to 6.2 m in length. Newborns tend to be 2.5 to 3 m in length,with and unknown weight.

These animals have a spindle-shaped body with a rounded to slightly bulging melon that ends in a long slender beak. The flippers are small, narrow, and rounded. The dorsal fin is set far past the body and is falcate in shape.

The whales are mainly bluish-black to dark purplish in color with patches of white on the underside, between the flippers, on the beak, and in a band around the head. There are also black patches over the eyes and forehead.

The most distinctive morphological characteristic of M. layardii is the single pair of mandibular teeth that are found only in adult males. These teeth curve over the upper jaw allowing the mouth to open only 11 to 13 cm. It is assumed that these teeth are used for intraspecific competition between males due to the high number of scars observed on the males.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes shaped differently
• ornamentation ornamentation

Reproduction

The mating system of M. layardii has not been observed.

Little is known about their reproductive behavior. It is thought that mating occurs in summer and calving occurs in summer to autumn after a 9 to 12 month gestation period.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• viviparous viviparous

There have been no studies of parental care in M. layardii . However, groups consisiting of a single female with calf pairs are often observed. In general, newborn cetaceans are precocial. They are able to follow the mother from birth. Although the female nurses the offspring, the duration of lactation is not known for this species. The role of the male in parental care is likewize unknown.

• Parental Investment
• no parental involvement
• precocial precocial
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifespan/Longevity

Lifespan of M. layardii is unknown. However, members of other species in the genus are reported to have lived from 27 to 48 years.

Behavior

Strap-toothed whales tend to shy away from boats, therefore they are rarely seen in the wild. When they are observed it is reported that they slowly sink below the surface of the water and rise again 150 to 250 meters away. Sometimes an individual will perform a lateral roll, exsposing a single flipper. Typically the dives last 10 to 15 minutes.

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• motile motile

Home Range

The home range of these animals has not been reported.

Communication and Perception

The large tusks in adult males are presumably a form of visual or tactile communication. Other toothed whales also use echolocation. It is likely that there are some forms of accoustic communication within the species, also.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• echolocation echolocation
• chemical chemical

Food Habits

Twenty-four species of oceanic squid, along with some deep sea fish make up the main diet of strap-toothed whales. Confusion and fascination surround the feeding habits of these whales due to the enlarged mandibular teeth in the males. At first they were thought to interfere with feeding, but it is now thought that they may act as "guide rails" to send food to the throat. Even this hypothesis is questioned because it is quite possible that M. layardii , like other beaked whales, suck food into their mouths, regardless if how far they can open their mouths.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • molluscivore molluscivore

• Animal Foods
• fish
• mollusks

Predation

These whales may be prey for killer whales.

Ecosystem Roles

Strap-toothed whales feed on a variety of marine organisms. they are therefore likely to have some impact on populations of these organisms.

Economic Importance for Humans: Positive

These animals are not reported to have any positive economic impact on humans.

Economic Importance for Humans: Negative

These animals are not reported to have any negative impacts on humans.

Conservation Status

Mesoplodon layardii is a species which is threatened by many things: possible entanglement in drift nets and other nets; competition from expanding fisheries, especially on squids; pollution leading to accumulation of DDT and PCBs in body tissues; and they are the most stranded Ziphiid in Australia. In 1982, the National Stranding Contigency Plan was designed to outline scientific objectives and appropriate biological/veterinary research activies for the stranded whales.

Another focus for the conservation efforts lies in the development of objectives and agreements to protect cetaceans and their environment under federal and state laws. Strap-toothed whales are listed on Appendix II of CITES.

Other Comments

There are many common names listed for M. layardii . The most frequently used are strap-toothed whale, strap-toothed beaked whale, and Layard's beaked whale.

Additional Links

Encyclopedia of Life

Contributors

Nancy Shefferly (editor), Animal Diversity Web.

Andrea Flohr (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

References

Bannister, J., C. Kemper, R. Warnke. 2001. "The Action Plan for Australian Cetaceans" (On-line ). Accessed 11/04/02 at http://www.ea.gov.au/coasts/species/cetaceans/actionplan/whaleap5z.html .

MacLoed, C. 2000. Species Recognition as a Possible Function for Variations in Position and Shape of the Sexually Dimorphic Tusks of Mesoplodon Whales. Evolution , 54/6: 2171-2173. Accessed 12/03/02 at http://www.bioone.org .

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition . Baltimore and London: The Johns Hopkins University Press.

Sekiguchi, K., N. Klages, P. Best. 1996. The Diet of Strap-toothed Whales(Mesoplodon layardii). Journal of Zoology,London , 239/3: 453-463.

Texas A&M University-Corpus Christi. 2002. "Texas Marine Mammal Stranding Network" (On-line ). Accessed 11/04/02 at http://www.sci.tamucc.edu/tmmsn/29Species/MoreSpec/straptoothedwhale.html .

The Whale and Dolphin Conservation Society. 2002. "The Whale and Dolphin Conservation Society" (On-line ). Accessed 11/04/02 at http://www.wdcs.org .