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Watasenia scintillans

By Krupa Patel and Dorothy Pee

Ge­o­graphic Range

The ge­o­graphic range of Watase­nia scin­til­lans is the West­ern Pa­cific ocean around Japan. (BBC, 2005)

Habi­tat

Watase­nia scin­til­lans is a ma­rine an­i­mal found in depths of 200 to 400 me­ters. (BBC, 2005)

  • Range depth
    200 to 400 m
    656.17 to 1312.34 ft

Phys­i­cal De­scrip­tion

Watase­nia scin­til­lans is a small cephalo­pod, grow­ing to 7-8 cm. The fire­fly squid is equipped with spe­cial light pro­duc­ing or­gans called pho­tophores. Pho­tophores are found in many parts of the body but large ones are usu­ally found on the tips of the ten­ta­cles as well as around the eyes. These lights can be flashed in uni­son or al­ter­nated in pat­terns. This squid has arms with hooks and ten­ta­cles with hooks and one se­ries of suck­ers. The mouth cav­ity has dark pig­men­ta­tion. (Tsuchiya, 2007)

  • Average length
    7.62 cm
    3.00 in

De­vel­op­ment

Fer­til­ized eggs hatch in 6-14 days de­pend­ing on the water tem­per­a­ture, which varies from six to 16 de­grees Cel­sius. Higher tem­per­a­tures en­cour­age quicker hatch­ing.

At 15 de­grees Cel­sius, one hour after fer­til­iza­tion, polar bod­ies ap­pear, fol­lowed in five hours with first cleaveage. By 10 hours, 100 or more cells have been formed, and around 16 hours the em­bry­onic lobe has been de­vel­oped. The em­bry­onic lobe cov­ers about half of the egg in a day and a half. In four days, pri­mor­dial eyes are pre­sent and oral de­pres­sion starts. A day later, pri­mor­dial arms, man­tle, and fun­nel ap­pear and then chro­matophores ap­pear on the man­tle and the eyes are de­vel­oped. Final organ and chro­matophore for­ma­tion and hatch­ing oc­curs in 8-8.5 days. (Tsuchiya, 2007)

Re­pro­duc­tion

Bi­o­lu­mi­nes­cent pho­tophores can at­tract mates and be used for com­mu­ni­ca­tion with other squids. (BBC, 2005)

The spawn­ing sea­son runs from March to May. Dur­ing this time, fire­fly squids can be seen gath­er­ing in large num­bers to lay their eggs. Once the eggs have been re­leased into the water and fer­til­ized, the adult squid die. This com­pletes the one-year life cycle of the squid. ("Fire­fly Squid", 2010)

  • Breeding interval
    Once yearly
  • Breeding season
    March - May
  • Average age at sexual or reproductive maturity (female)
    1 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Adult fire­fly squids die after eggs have been re­leased into the water and fer­til­ized. ("Fire­fly Squid", 2010)

  • Parental Investment
  • no parental involvement

Lifes­pan/Longevity

The fire­fly squid lives for about one year. (BBC, 2005)

Be­hav­ior

Watase­nia scin­til­lans are gen­er­ally deep sea dwellers. They spend their days at depths of 200-400 m but swim up to the sur­face at night to cap­ture prey. Watase­nia scin­til­lans also rise up to the sur­face dur­ing their pe­riod of spawn­ing, ap­pear­ing in huge schools along the shore­line. (An­i­mal Planet, 2011; BBC, 2005; Dahlgren, 1922)

Com­mu­ni­ca­tion and Per­cep­tion

The pho­tophores along the body and ten­ta­cles of the Watase­nia scin­til­lans are used to at­tract prey, pro­vide cam­ou­flage, frighten preda­tors, and to at­tract a mate. The fire­fly squid also has highly de­vel­oped vi­sion. Its eyes con­tain three dif­fer­ent types of light-sen­si­tive cells and are be­lieved to be ca­pa­ble of dis­tin­guish­ing dif­fer­ent col­ors. (BBC, 2005)

  • Communication Channels
  • visual

Food Habits

Watase­nia scin­til­lans con­sumes a diet con­sist­ing of shrimp, crabs, fish, and plank­tonic crus­taceans. The pho­tophores on the tips of its ten­ta­cles are used in a flash­ing pat­tern to at­tract prey, es­pe­cially fish. (Hayashi and Hi­rakawa, 1997; Hooper, 2003)

  • Animal Foods
  • fish
  • aquatic crustaceans
  • other marine invertebrates
  • zooplankton

Pre­da­tion

The pho­tophores along the body of the squid can be used against preda­tors in ei­ther a warn­ing form or as counter-il­lu­mi­na­tion cam­ou­flage. The north­ern fur seal, Cal­lorhi­nus ursi­nus, is a known preda­tor. (BBC, 2005; Mori, et al., 2001)

Ecosys­tem Roles

Watase­nia scin­til­lans are prey for north­ern fur seals, Cal­lorhi­nus ursi­nus and is a preda­tor of shrimp, fish, and plank­tonic crus­taceans. This squid is also a host to ne­ma­tode lar­vae. (Aoyama, et al., 1996; Hooper, 2003; Mori, et al., 2001; Smyth, 1994)

Com­men­sal/Par­a­sitic Species
  • Ne­ma­toda

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

Watase­nia scin­til­lans can be eaten raw, known as Ho­taruika in Japan, or cooked. These species of squid also draw large crowds dur­ing their spawn­ing sea­son at Toyama Bay in Japan. The large schools that swim up to the shal­low wa­ters light up the dark water along the shore, giv­ing tourists a night­time show. This spec­ta­cle has led to the bay being named a Spe­cial Nat­ural Mon­u­ment and con­struc­tion of a mu­seum de­voted to the species. ("Travel Guide Toyama", 2009; Aoyama, et al., 1996; Hooper, 2003)

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Eat­ing raw Watase­nia scin­til­lans, known in Japan as Ho­taruika, that is in­fected with spiru­rina type X lar­vae, be­long­ing to the phy­lum Ne­ma­toda, can cause ab­dom­i­nal pain, nau­sea and vom­it­ing, di­ar­rhea, creep­ing erup­tion, and ileus (bowel ob­struc­tion). (; Aoyama, et al., 1996; Smyth, 1994)

Con­ser­va­tion Sta­tus

Watase­nia scin­til­lans is not pro­tected under any con­ser­va­tion pro­gram.

Con­trib­u­tors

Krupa Patel (au­thor), Rut­gers Uni­ver­sity, Dorothy Pee (au­thor), Rut­gers Uni­ver­sity, David V. Howe (ed­i­tor), Rut­gers Uni­ver­sity, Renee Mul­crone (ed­i­tor), Spe­cial Pro­jects.

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

aposematic

having coloration that serves a protective function for the animal, usually used to refer to animals with colors that warn predators of their toxicity. For example: animals with bright red or yellow coloration are often toxic or distasteful.

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

causes disease in humans

an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

food

A substance that provides both nutrients and energy to a living thing.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

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.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

photic/bioluminescent

generates and uses light to communicate

piscivore

an animal that mainly eats fish

saltwater or marine

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

seasonal breeding

breeding is confined to a particular season

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

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

visual

uses sight to communicate

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

Ref­er­ences

Sea and Sky. 2010. "Fire­fly Squid" (On-line). Deep sea crea­tures. Ac­cessed June 20, 2011 at http://​www.​seasky.​org/​deep-sea/​firefly-squid.​html.

Toyama Pre­fec­tural Tourism As­so­ci­a­tion. 2009. "Travel Guide Toyama" (On-line). Ac­cessed June 21, 2011 at http://​www.​info-toyama.​com/​english/​guide/​index.​html.

An­i­mal Planet, 2011. "Squid" (On-line). An­i­mal Planet. Ac­cessed June 19, 2011 at http://​animal.​discovery.​com/​invertebrates/​squid/​.

Aoyama, S., Y. Hi­noue, H. Taka­hashi, Y. Yoshim­itsu, Y. Kusajima, T. Hi­rono, N. Takayanagi, N. Akao, K. Kon­dou. 1996. Clin­i­cal study of ten cases with acute ab­domen after eat­ing raw fire­fly squid (Watase­nia scin­til­lans, Ho­taruika), which are prob­a­bly due to type X lar­vae of the sub­or­der spiru­rina. Nip­pon Shokak­ibyo Gakkai Zasshi, 93: 312-321.

BBC, 2005. "An­i­mal fact files: fire­fly squid" (On-line). Ac­cessed June 19, 2011 at http://​www.​bbc.​co.​uk/​nature/​blueplanet/​factfiles/​molluscs/​firefly_​squid_​bg.​shtml.

Dahlgren, U. 1922. Phos­pho­res­cent plants and an­i­mals. Nat­ural His­tory, 22: 19.

Hayashi, S., K. Hi­rakawa. 1997. Diet com­po­si­tion of the fire­fly squid, Watase­nia scin­til­lans, from Toyama Bay, South­ern Japan Sea. Bul­letin of the Japan Sea Na­tional Fish­eries Re­search In­sti­tute, 47: 57-66.

Hooper, R. 2003. "The Japan Times On­line" (On-line). Ac­cessed June 20, 2011 at http://​search.​japantimes.​co.​jp/​cgi-bin/​fe20030911at.​html.

Mori, J., T. Ku­bodera, N. Baba. 2001. Squid in the diet of north­ern fur seals, Cal­lorhi­nus ursi­nus, caught in the west­ern and cen­tral North Pa­cific Ocean. Fish­eries Re­search, 52: 91-97.

Shi­mo­mura, O. 2006. Bi­o­lu­mi­nes­cence: Chem­i­cal Prin­ci­ples and Meth­ods. Sin­ga­pore: World Sci­en­tific Pub­lish­ing Co. Pte. Ltd..

Smyth, J. 1994. In­tro­duc­tion to An­i­mal Par­a­sitol­ogy. Cam­bridge: Cam­bridge Uni­ver­sity Press.

Tsuchiya, K. 2007. "Watase­nia scin­til­lans" (On-line). Ac­cessed June 20, 2011 at http://​tolweb.​org/​Watasenia_​scintillans/​19645.

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Classification

Classification

  • Kingdom Animalia animals
  • Class Cephalopoda
  • Order Teuthida
  • Family Enoploteuthidae
  • Genus Watasenia
  • Species Watasenia scintillans