Mesoplodon perrini

Geographic Range

At present, Perrin's beaked whales ( Mesoplodon perrini ) are only found in the northern Pacific Ocean. Four of the five known specimens of this whale species were found stranded along the coast of southern California within 85 kilometers of one another in the late 1970's. Although this suggests an eastern distribution within the North Pacific, there is currently too little information to come to any firm conclusions. Scars attributed to cookie cutter sharks ( Isistius ) that were found on one of the type specimens indicates that M. perrini may migrate through tropical regions where this shark is found in surface waters. However, it could also indicate a more northern distribution of Isistius .

• Biogeographic Regions
• pacific ocean pacific ocean
  • native native

Habitat

Like most other ziphiids , Mesoplodon perrini spends the majority of its time in deep oceanic waters over 1,000 meters deep.

• Habitat Regions
• temperate temperate
• saltwater or marine saltwater or marine

• Aquatic Biomes
• pelagic pelagic

Physical Description

Mesoplodon perrini is similar in shape to other members of this genus, with a short head and tail, a long abdomen, and a deep caudal peduncle. Like its closest relatives, Mesoplodon hectori and Mesoplodon peruvianus , it has a relatively short snout. It has a crescent-shaped blowhole with the tips facing towards the head. The mouth forms a straight line, and a series of grooves are present along the throat. As adults, M. perrini have dark gray coloration on their backs which grades to white on their undersides. The ventral side of their tail flukes is a lighter shade of grey with striations. Juvenile type specimens have a somewhat different color pattern, with a white area around the throat and a dark grey patch around the rostrum and eyes. Only the original five beached specimens have been accurately measured. The adult female was approximately 4.4 meters from nose to tail, while the adult male was 3.9 meters in length. The other three specimens were juvenile males, which were measured at 2.1, 2.2, and 2.4 meters.

Like other mesoplodont whales , male M. perrini have a set of tusk-like teeth that originate from the lower jaw. These tusks are not present in females. It is thought that they play a role in intrasexual competition, as is evidenced by a series of long, white scars along the flank of the adult male type specimen. The tusks may also help these whales distinguish individuals belonging to their species from those of similar, sympatric species.

Mesoplodon perrini is similar in appearance to a related species, M. hectori . In fact, many of the type specimens of this species were originally identified as the latter species, and were only designated as a separate species by Dalebout in 2002. Morphological characteristics that set these two species apart include minor differences in the cranium, teeth, and mandible.

Most of the characteristics that set M. perrini apart from related species are molecular. Substantial differences in mtDNA and cytochrome b form the basis for its diagnosis as a new species. Morphological similarities suggested that the closest relative of M. perrini was M. hectori . However, based on the molecular characters, Dalebout et al. concluded that its true sister species is M. peruvianus . This conclusion was later supported by analysis of nuclear actin sequences by Dalebout et al. (2004).

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

• Sexual Dimorphism
• ornamentation ornamentation

Reproduction

No information is available on mating in Mesoplodon perrini .

There is currently little information available regarding reproductive habits of Mesoplodon perrini or other ziphiids . The two adult type specimens were both sexually mature, and an analysis of the teeth indicated an approximate age of 9 years for both of them.

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

Little is known about parental investment in Mesoplodon perrini . However, the 2.1 meter type specimen had a fringed tongue, which indicates that it was not yet weaned when it died. Researchers suspect that it was the calf of the adult female type specimen, and that it was still dependent on her when she was stranded. Like all other whales , young are able to swim soon after birth.

• Parental Investment
• precocial precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Since Mesoplodon perrini is such an elusive species, as is typical of this genus, nothing is known about its longevity and life history.

Behavior

Sightings of Mesoplodon perrini or any other mesoplodont whales in the wild are extremely rare, as they spend most of their lives in the open ocean and tend to stay far away from boats on the rare occasions that they are sighted. Consequently, what we know of their behavior comes from a few eyewitness reports and evidence found on type specimens.

Mesoplodont whales tend to be less social than other toothed whales , such as dolphins or porpoises. Sightings of a related species, Mesoplodon stejneri , reveal that, while these whales are often found alone or in small groups, they can form pods of as many as 15 individuals. Members of these pods tend to stay extremely close to one another, appearing to be almost touching each other, and they surface or dive together.

It is suspected that male Mesoplodon perrini frequently fight with one another, as is the case with other members of their genus. This is supported by parallel linear scars present on the flank of the adult male type specimen. These markings were probably made with a single tooth, which is unusual considering that this species has apical teeth.

• Key Behaviors
• natatorial natatorial
• motile motile
• social social

Home Range

Little is currently known about the home ranges of M. perrini . There is some evidence that this species is migratory or nomadic, but this has yet to be confirmed.

Communication and Perception

Although little is known about how Mesoplodon perrini communicates, research on other species of mesoplodont whales indicates that they have the ability to echolocate. A 2004 study involving tagged Mesoplodon densirostris found that these animals are very vocal, most frequently emitting ultrasonic clicks that are well outside the range of human hearing. This research also revealed that these whales only emit clicks when they are below 200 meters depth, where they most commonly forage.

• Communication Channels
• acoustic acoustic

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

Food Habits

At present, there is limited information regarding the diet and feeding habits of Mesoplodon perrini . However, it is suspected that these whales feed primarily on squid and some fish, as do many other ziphiids . This is supported by gut content analysis of two of the type specimens. One contained the eye lens of a squid, and the other contained two squid beaks (identifed as Octopoteuthis deletron ) and unidentified vertebrate parts.

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

• Animal Foods
• fish
• mollusks

Predation

The only known predators of Mesoplodon perrini are sharks and humans. Scars left by cookiecutter shark bites ( Isistius ) were present on one of the type specimens, but they did not appear to have caused any lasting damage. Although mesoplodont whales were never harvested commercially, there have been reports of them being taken by humans from time to time.

Ecosystem Roles

Members of this species consume fish and squid. They are probably not significant as prey for other animals.

Economic Importance for Humans: Positive

Members of this species are probably to rare to be important to humans.

Economic Importance for Humans: Negative

Members of this species are probably too rare to have a significant negative impact on humans.

Conservation Status

Since so little is known about the habits of Mesoplodon perrini , and so few individuals have been encountered in the wild, it is difficult to adequately evaluate how many individuals are left and what potential threats (if any) there are to the survival of the species. According to the ICUN, this species has the potential to become caught in certain types of fishing gear, such as deepwater gill nets used for capturing large pelagic fish species. Like other marine mammals, it may also be negatively impacted by navy sonar and loud noises generated by seismic exploration. Climate change may also cause their range to change or grow smaller, but since the specific range of M. perrini has yet to be determine, this assertion is presently based only on conjecture.

Other Comments

Mesoplodon perrini was named to honor American cetologist William F. Perrin.

Additional Links

Encyclopedia of Life

Contributors

Katie Birkett (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

References

Dalebout, M., C. Baker, J. Mead, V. Cockcroft, T. Yamada. 2004. A Comprehensive and Validated Molecular Taxonomy of Beaked Whales, Family Ziphiidae. Journal of Heredity , 95/6: 459-473.

Dalebout, M., J. Mead, C. Baker, A. Baker, A. Van Helden. 2002. A New Species of Beaked Whale Mesoplodon perrini Sp. N. (Cetacea: Ziphiidae) Discovered Through Phylogenetic Analyses of Mitochondrial DNA Sequences. Marine Mammal Science , 18/3: 577-608.

Johns, M., P. Madsen, W. Zimmer, N. Aguilar de Stoto, P. Tyack. 2004. Beaked whales echolocate on prey. Proceedings of the Royal Society of London , 271: S383-S386.

Loughlin, T., M. Perez. 1985. Mesoplodon stejneri. Mammalian Species , 250: 1-6.

MacLeod, 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.

Mead, J. 2007. Stomach Anatomy and Use in Defining Systemic Relationships of the Cetacean Family Ziphiidae. The Anatomical Record , 290: 581-595.

International Union for the Conservation of Nature and Natural Resources. 2008. "IUCN 2008 Red List - Mesoplodon perrini" (On-line). The IUCN Red List of Threatened Species. Accessed April 07, 2009 at http://www.iucnredlist.org/details/41759 .