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Neophocaena phocaenoidesfinless porpoise

By Lindasy DuVall

Geographic Range

Neophocaena phocaenoides is found in the coastal waters and rivers of Southeast Asia. It is concentrated in the eastern IndoPacific region. Neophocaena phocaenoides can be found from Pakistan to Korea, Japan, Borneo and Java. (Gaskin 1982, Nowak 1991)

Habitat

Neophocaena phocaenoides lives in both fresh and salt water habitats. It is found in shallow coastal waters such as the Sea of Japan as well as fresh water rivers like the Yangtze river in China. Neophocaena phocaenoides is occasionaly found in inland lakes which have been cut off from the ocean but are still salt water. Neophocaena phocaenoides seems to prefer rocky promonotories and strong currents (Ganslosser 1988).

  • Aquatic Biomes
  • rivers and streams
  • coastal

Physical Description

Neophocaena phocaenoides is sometimes called the Black Finless Porpoise because of the common misconception that its skin is black. In reality, the upper portions of N. phocaenoides are gray with touches of blue on the back and sides. The ventral parts are paler. Pale spots do however decrease with age, and the skin turns black immediately after death. Further, the skin coloring differs from pale in oceanic and brackish waters, to almost black in rivers. Neophocaena phocaenoides has no dorsal fin but has instead has a midline dorsal ridge. This ridge contains horny papillae. Neophocaena phocaenoides is the smallest cetacean and grows to only 150-190cm. It has a distinct eel-like shape due to its lack of dorsal fin and round, beakless head. The jaw of N. phocaenoides contains 15-21 spade shaped teeth on each side of the upper and lower jaw. (Ganslosser 1988, Herman 1980, Nowak 1991)

  • Range mass
    30 to 45 kg
    66.08 to 99.12 lb

Reproduction

Neophocaena phocaenoides reaches sexual maturity by the age of 2. Reproductive cycles differ among geographic groups such as those located near Japan and those near China. The breeding cycle is 1-2 years and gestation lasts between 10 and 11 months. Births occur between February and August and there is usually 1 young per birth. Newborns are around 25kg and are weaned between September and June. Neophocaena phocaenoides has been found to live up to 23 years. (Bryden & Harrison 1986, Nowak 1991).

  • Breeding interval
    The breeding cycle is 1-2 years
  • Average number of offspring
    1
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    10 to 11 months
  • Range weaning age
    7 to 10 months
  • Range age at sexual or reproductive maturity (female)
    2 (high) years
  • Range age at sexual or reproductive maturity (male)
    2 (high) years

Mothers carry their offspring on a patch of skin on the dorsal surface which is covered with horny papillae. This acts like a saddle on which the young can attach and be carried. Although obviously for carrying young, the horny papillae contain nerve endings and may be a means of auxillary orientation. This "extra" means of orientation could be very beneficial to N. phocaenoides since it often lives in murky waters.

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

Lifespan/Longevity

Behavior

Neophocaena phocaenoides is a relatively slow animal. It rolls to the surface to breath and is rarely observed jumping out of the water. Maximum dives last up to 11-15 seconds. It forms mostly small schools and is rarely seen in groups of more than 4. More often, N. phocaenoides is solitary or in mother-offspring groups. Some of the groups of N. phocaenoides (mainly the Japanese groups) are migratory. They frequent the Inland Sea during the spring and migrate to the Pacific coast from late summer to midwinter. (Gaskin 1982, Ganslosser 1988, Nowak 1991)

Communication and Perception

Food Habits

Neophocaena phocaenoides feeds mainly in the euphotic zone. It eats benthic invertebrates, cephalopods such as squid, and small demersal fish. Neophocaena phocaenoides is a very aggresive hunter, and fish have been observed jumping out of the water when chased by it (Bryden & Harrison 1986). (Gaskin 1982)

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Economic Importance for Humans: Positive

Neophocaena phocaenoides is hunted by humans for its meat, skin and oil (Nowak 1991).

Conservation Status

Although N. phocaenoides is not endangered, there are many threats to its survival as individuals if not as a species. Neophocaena phocaenoides is effected by pollution as well as bottom dredging. It is also killed by motor boat collisions, hunters, fish and shrimp nets, and its natural predator, the shark. (Bryden & Harrison 1986, Nowak 1991)

Other Comments

Neophocaena phocaenoides appears to be very adaptable and is found in habitats which other species have abandoned. These include the Tung-Ting Lake in China, which is landlocked and extremely shallow. However, N. phocaenoides isn't as quick to adapt to human ways. They tend to eat objects off the river bottom, including things as detrimental to their health as bottle caps thrown in the water by humans; these appear to be a major cause of death (Bryden & Harrison 1986).

Contributors

Lindasy DuVall (author), University of Michigan-Ann Arbor.

Glossary

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

coastal

the nearshore aquatic habitats near a coast, or shoreline.

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.

iteroparous

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).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

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

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

piscivore

an animal that mainly eats fish

seasonal breeding

breeding is confined to a particular season

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.

solitary

lives alone

tactile

uses touch to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Bryden, M. and Harrison, R. 1986. Research on Dolphins. Clarendon Press, Oxford.

Ganslosser, U. 1988. Grizimek's Encyclopedia. McGraw-Hill Publishing, New York. Vol 4. pgs. 386, 414-415.

Gaskin, D.E. 1982. The Ecology of Whales and Dolphins. Heinemann, London. pgs. 3, 127, 229, 235.

Herman, L. 1980. Cetacean Behavior. John Wiley and Sons, New York. pg 268.

Nowak, R.M. 1991. Walker's Mammals of the World. Johns Hopkin's University Press, Baltimore. Vol 2. pgs. 1005-1006.

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