Watasenia scintillans | INFORMATION

Scientific Classification

Rank	Scientific Name
Kingdom	Animalia animals
Class	Cephalopoda
Order	Teuthida
Family	Enoploteuthidae
Genus	Watasenia
Species	Watasenia scintillans

By Krupa Patel and Dorothy Pee

Geographic Range

The geographic range of Watasenia scintillans is the Western Pacific ocean around Japan.

Biogeographic Regions
pacific ocean
- native

Habitat

Watasenia scintillans is a marine animal found in depths of 200 to 400 meters.

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.

Other Physical Features
ectothermic
heterothermic
bilateral symmetry

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.

Development - Life Cycle
metamorphosis

Reproduction

Bioluminescent photophores can attract mates and be used for communication with other squids.

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.

Key Reproductive Features
seasonal breeding
broadcast (group) spawning
oviparous

Adult firefly squids die after eggs have been released into the water and fertilized.

Parental Investment
no parental involvement

Lifespan/Longevity

The firefly squid lives for about one year.

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.

Key Behaviors
motile

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.

Communication Channels
visual

Other Communication Modes
photic/bioluminescent

Perception 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.

Primary Diet
carnivore
- piscivore
- eats non-insect arthropods

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.

Anti-predator Adaptations
aposematic
cryptic

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.

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.

Positive Impacts
food
ecotourism

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).

Negative Impacts
injures humans
- causes disease in humans

Conservation Status

Watasenia scintillans is not protected under any conservation program.

Additional Links

Encyclopedia of Life

Contributors

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

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

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

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.

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

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

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.

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.

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.

seasonal breeding: breeding is confined to a particular season

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

motile: having the capacity to move from one place to another.

visual: uses sight to communicate

photic/bioluminescent: generates and uses light to communicate

visual: uses sight to communicate

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

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.

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.

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

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.

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).

carnivore: an animal that mainly eats meat

piscivore: an animal that mainly eats fish

References

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 .

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 .