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Mesoplodon peruvianuspygmy beaked whale

By Jasmine Bhatia

Geographic Range

Mesoplodon peruvianus was discovered in Peru in 1991 and is only known in Peruvian waters, although there have been two documented strandings on Mexican shores (The Whale and Dolphin Conservation Society, 2001). Strandings and captures have taken place between 11 and 15 degrees south latitude, off the coast of central and southern Peru. This is thought to be the southern end of the range of M. peruvianus (Texas A&M University - Corpus Christi, 2001).

Habitat

This species lives in mid- to deep-sea waters off of the Peruvian coast.

Physical Description

At birth, M. peruvianus is between 1.5-1.6 m long, while the adult is between 3.4-3.7 m. This whale is the smallest species of Mesoplodon (World Biodiversity Database, 2001). This species is, on its upper side, uniformly dark gray fading to light gray on the underside (dark gray posterior to the navel). The body is spindle-shaped. The short, dark-tipped beak precedes a narrow head with an indentation at the blowhole. This species has two tiny teeth on its lower jaw. The small, triangular dorsal fin has a wide base and is positioned far behind the center of the animal. The flukes have no notches, and their tips are slightly pointed. (All information from Texas A&M University - Corpus Christi, 2001 unless otherwise noted.)

M. peruvianus exhibits sexual dimorphism. The males of the species are larger than the females (World Biodiversity Database, 2001).

The features that distinguish this Mesoplodon species from others of its genus are most prominent in males (Webb, 1998).

  • Range length
    3.4 to 3.7 m
    11.15 to 12.14 ft

Reproduction

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

Behavior

Very little is known about this cetacean. Scientists have examined 13 dead specimens and few more than 5 reliable sightings have been recorded (The Whale and Dolphin Conservation Society, 2001). There are several reasons for the lack of knowledge of this whale. First, the blow of M. peruvianus's is inconspicuous, making it hard to spot (Cetacea, 2001). The species avoids watercraft and can be mistaken for members of other Mesoplodon species (Cetacea, 2001).

All recorded strandings have involved single individuals, but the species can be spotted in groups of 2-3, with the third usually being a calf (Cetacea, 2001).

Communication and Perception

Food Habits

Although feeding by M. peruvianus has not been witnessed, it is believed that this species eats mid- to deep-sea fish and squid (Cetacea, 2001).

  • Animal Foods
  • fish
  • mollusks

Predation

Humans are the only known threat to M. peruvianus. This whale becomes tangled in fishing nets, which initially led to the discovery of this species.

Conservation Status

Other Comments

Little is known about M. peruvianus due to its inaccessible habitat and elusive nature.

Mesoplodon peruvianus has several common names. Among them are Lesser Beaked Whale, Peruvian Beaked Whale and Pygmy Beaked Whale (The Whale and Dolphin Conservation Society, Cetacea and Texas A&M University - Corpus Christi, 2001).

Texas A&M University - Corpus Christi reports that M. peruvianus can most easily be mistaken for Hector's beaked whale (Texas A&M University - Corpus Christi, 2001).

Contributors

Jasmine Bhatia (author), University of Michigan-Ann Arbor, Ondrej Podlaha (editor), University of Michigan-Ann Arbor.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

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.

World Map

bilateral symmetry

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

endothermic

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.

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

piscivore

an animal that mainly eats fish

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

References

Cetacea, 2001. "Cetacea: *Mesoplodon peruvianus* (Lesser beaked whale)" (On-line). Accessed November 17, 2001 at http://www.cetacea.org/lesser.htm.

Texas A&M University - Corpus Christi, 2001. "Lesser beaked whale: *Mesoplodon peruvianus*" (On-line). Accessed November 17, 2001 at http://www.sci.tamucc.edu/tmmsn/29Species/MoreSpec/lesserbeakedwhale.html.

The Whale and Dolphin Conservation Society, 2001. "WDCS - The Whale and Dolphin Conservation Society" (On-line). Accessed November 17, 2001 at http://www.wdcs.org.

Webb, J. Spring 1998. Scientist works to create portraits of whale and dolphin species. Smithsonian Institution Research Reports, 92.

World Biodiversity Database, 2001. "ETI - World Biodiversity Database" (On-line). Accessed November 15, 2001 at http://www.eti.uva.nl/Database/WBD.html.

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