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. (Sekiguchi, et al., 1996; "Texas Marine Mammal Stranding Network", 2002)
Strap-toothed whales are found in deep oceanic waters of the temperate to subantartic regions. They may use adjacent waters for feeding and calving. (Bannister, et al., 2001)
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. ("Texas Marine Mammal Stranding Network", 2002; "The Whale and Dolphin Conservation Society", 2002)
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 Whale and Dolphin Conservation Society", 2002)
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. (MacLoed, 2000; Sekiguchi, et al., 1996)
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. (Bannister, et al., 2001)
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. (Bannister, et al., 2001)
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. (Bannister, et al., 2001; "Texas Marine Mammal Stranding Network", 2002)
The home range of these animals has not been reported.
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. (MacLoed, 2000)
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. (Sekiguchi, et al., 1996)
These whales may be prey for killer whales. (Bannister, et al., 2001)
Strap-toothed whales feed on a variety of marine organisms. they are therefore likely to have some impact on populations of these organisms. (Sekiguchi, et al., 1996)
These animals are not reported to have any positive economic impact on humans.
These animals are not reported to have any negative impacts on humans.
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. (Bannister, et al., 2001)
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. (Bannister, et al., 2001)
Nancy Shefferly (editor), Animal Diversity Web.
Andrea Flohr (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
union of egg and spermatozoan
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
an animal that mainly eats fish
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
uses touch to communicate
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
young are relatively well-developed when born
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.
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.