Overview

Distribution

Euprymna scolopes is a sepiolid squid endemic to the oceanic habitats surrounding the Hawaiian Islands. This squid can greatly affect the relative abundance and geographic distribution of its bacterial symbiont Vibrio fischeri.

Biogeographic Regions: pacific ocean (Native )

  • Ruby, R., K. Ho Lee. 1998. The Vibrio fischeri-Euprymna scolopes light organ association: current ecological paradigms. Applied and Environmental Biology, 3: 805-812. Accessed January 19, 2013 at http://aem.asm.org/content/64/3/805.full.pdf+html.
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Range Description

This species occurs in shallow water off Hawaii (Reid and Jereb 2005).
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Physical Description

Morphology

Euprymna scolopes is one of the smallest and slimmest sepiolid squids. The mantle plus tentacles measure an average of 35 mm (1.4 in) in length, and weighs an average of 2.76 grams (0.09 oz). The birth mass of a hatchling is an average 0.005 grams (0.00018 oz). Males have slightly larger suckers than females, with thinner posterior mantles. Both sexes have a pair of unique paddle shaped fins that aid in swimming. A feature unique to Euprymna scolopes is the bilobed and bioluminescent light organ present inside the squid’s mantle cavity. This organ, which functions through its interaction with its symbiotic partner Vibrio fischeri, provides light, allowing the squid to hunt its prey at night. This squid also possesses metabracial vesicles, which function as the eyes of this bobtail squid. The vesicles allow the squid to perceive and manipulate the amount of light it can give off, so the squid can camouflage itself in a process known as counterillumination.

Range length: 20 to 30 mm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes shaped differently

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Type Information

Paratype for Euprymna scolopes Berry, 1913
Catalog Number: USNM 727393
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Sex/Stage: ; larvae
Preparation: Alcohol (Ethanol)
Year Collected: 1902
Locality: Molokai Island, Off Kalaupapa Leper Settlement,, Hawaii, United States, North Pacific Ocean
Vessel: Albatross R/V
  • Paratype: Berry, S. 1913. Proc. U.S. Natl. Mus. 45(1996): 564-565.
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Holotype for Euprymna scolopes Berry, 1913
Catalog Number: USNM 214380
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Sex/Stage: male;
Preparation: Isopropyl Alcohol
Year Collected: 1930
Locality: Molokai Island, North Coast, Off Kalaupapa Leper Settlement, 3/4 Deg., Hawaii, United States, North Pacific Ocean
Vessel: Albatross R/V
  • Holotype: Berry, S. 1913. Proc. U.S. Natl. Mus. 45(1996): 564-565.
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Ecology

Habitat

Euprymna scolopes is found in warm, shallow coastal waters 2-4 cm deep. This is unusual because most sepiolid squids reside in very deep water. Euprymna scolopes is often seen laying its eggs on the foundations of coral ridges. During the day, these squid are buried in the sand. At night, they emerge and wade through the sand with their bioluminescent light organ which allows them to see and hunt in the dark.

Habitat Regions: tropical ; saltwater or marine

Aquatic Biomes: benthic ; coastal

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Habitat and Ecology

Habitat and Ecology
This small species is found in shallow water inhabiting sandy and muddy areas near seagrass beds (Norman 2003). This species will glue sand grains to its body to form camouflage. This species buries itself in sand or mud during day and emerges at night to feed (Norman 2003). It has a light organ which emits just enough light to hide its silhouette at night from predators (Norman 2003). There has been much research performed on the bacteria held within its light organ (Norman 2003).

Systems
  • Marine
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Shallow coastal waters.
  • Jereb, P.; Roper, C.F.E. (Eds)(2005). An annotated an illustrated catalogue of cephalopod species known to date. Volume 1: Chambered nautilusses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae). FAO Species Catalogue for Fishery Purposes 4(1). FAO, Rome. 262p., 9 colour plates.
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Depth range based on 20 specimens in 1 taxon.
Water temperature and chemistry ranges based on 12 samples.

Environmental ranges
  Depth range (m): 21 - 1000
  Temperature range (°C): 5.183 - 24.695
  Nitrate (umol/L): 0.008 - 41.466
  Salinity (PPS): 34.323 - 35.154
  Oxygen (ml/l): 0.607 - 4.943
  Phosphate (umol/l): 0.122 - 2.982
  Silicate (umol/l): 1.242 - 90.947

Graphical representation

Depth range (m): 21 - 1000

Temperature range (°C): 5.183 - 24.695

Nitrate (umol/L): 0.008 - 41.466

Salinity (PPS): 34.323 - 35.154

Oxygen (ml/l): 0.607 - 4.943

Phosphate (umol/l): 0.122 - 2.982

Silicate (umol/l): 1.242 - 90.947
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Trophic Strategy

The primary component of the adult E. scolopes diet is mysid shrimp, and younger squids will also consume crustaceans in the genus Artemia. Euprymna scolopes is a cryptic "sit and wait" predator. The squid buries itself in the sand with its tentacles and wait for prey to pass by. Euprymna scolopes attacks by aiming all the arms at the prey and strikes using the two tentacles. If the squid misses the prey it remains buried and waits for another organism.

Animal Foods: aquatic crustaceans

Primary Diet: carnivore (Eats non-insect arthropods)

  • Archetti, M., N. Pierce, M. Hoffman, I. Scheuring, M. Frederickson, D. Yu. 2011. Economic game theory for mutualism and cooperation. Ecology Letters, 14: 1300-1312.
  • Fleisher, K., J. Case. 1995. Cephalopod predation facilitated by dinoflagellate luminescence. Biology Bulletin, 189: 263-271. Accessed January 19, 2013 at http://www.biolbull.org/content/189/3/263.full.pdf.
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Associations

Euprymna scolopes has a mutualistic relationship with the marine bacteria Vibrio fischeri, making the squid bioluminescent.

Although they are inhabitants of areas near coral reefs, there is no evidence to suggest Euprymna scolopes has an effect or relationship on the maintenance of the community around the reef.

Mutualist Species:

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As previously mentioned, Euprymna scolopes uses counterillumination to camouflage from predators. Another defense mechanism is burying itself in an outer covering made of sand. Last, the squid releases an amount of ink when they sense a stimuli indicating the presence of a predator. The pool of ink is used to deceive the predator and prevent attack by resembling the shape of the squid. Known predators of E. scolopes include lizardfish (family Synodontidae), barracuda (genus Sphyraena), and Hawaiian monk seal (Monachus schauinslandi).

Known Predators:

Anti-predator Adaptations: cryptic

  • Lee, P., M. McFall-Ngai, P. Callaerts, H. Gert de Cout. 2009. The Hawaiian bobtail squid (Euprymna scolopes): a model to study the molecular basis of eukaryote-prokaryote mutualism and the development and evolution of morphological novelties in cephalopods. Cold Spring Harbor Protocols, 11: 1-18. Accessed January 19, 2013 at http://www.medmicro.wisc.edu/labs/mcfall_ruby_papers/pdf/2009/Lee_GertdeCouet_2009_ColdSpringHarbProtoc_emerging.pdf.
  • Visick, K., M. McFall-Ngai. 2000. An exclusive contract: specificity in the Vibrio fischeri-Euprymna scolopes partnership. Journal of Bacteriology, April 2000: 1779-1787.
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Life History and Behavior

Behavior

Euprymna scolopes has a symbiotic relationship with a bioluminescent marine bacterium called Vibrio fischeri. This mutualistic relationship begins early in the life stages of the squid and development of the light organ results. The squid controls the amount and timing of the bioluminescence given off by the bacteria. When the bacteria are found outside of this mutualistic relationship the strength of the light given off is not nearly as strong as it is when it is housed inside the light organ of E. scolopes. This light organ is generally used for a specialized behavior known as counterillumination, which allows the organism to camouflage themselves and avoid predators.

Communication Channels: tactile ; chemical

Other Communication Modes: photic/bioluminescent

Perception Channels: polarized light ; tactile ; chemical

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Life Cycle

Euprymna scolopes develops rapidly and grows exponentially. After copulation, there is a 18-26 day embryonic period. The planktonic hatchling first emerges from the egg, and is initially aposymbiotic, meaning it cannot use its light organ. After several days, the hatchling develops into a planktonic paralarva that can partially make use of the light organ. The paralarva develops into a juvenile after ten days, and becomes mature enough to travel into shallower waters. After 130 days, when the squid is a subadult, the light organ fully functions for hunting and camouflage. The squid will have little to no further growth after 180 days. Male and female organisms, which occur in equal numbers, reach sexual maturation 60 days after hatching. Temperature may be a factor in the time to reach full sexual maturity. Interaction with Vibrio fischeri is not required for normal development and growth.

Development - Life Cycle: metamorphosis

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Life Expectancy

Euprymna scolopes has a lifespan that averages 2-3 months in the wild and 3-5 months in captivity.

Typical lifespan

Status: wild:
2 to 3 months.

Typical lifespan

Status: captivity:
3 to 5 months.

  • Montgomery, M., M. McFall-Ngai. 1993. Embryonic development of thelight organ of the sepiolid squid Euprymna scolopes Berry. Biological Bulletin, 3: 296-230.
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Reproduction

There is no information on the mating system of Euprymna scolopes.

Mating is initiated by the male, which grabs the female and places its spermatophore in the female's mantle. The female's mantle will become larger as it is filled with eggs. Mating lasts 30-50 minutes, and occurs mostly at night. Studies have shown that rainfall increases the amount of breeding. There are no specific seasonal breeding intervals for this squid. Females tend to lay eggs in the morning in shallow areas on coral ridges. Clutch sizes vary between 50-200 eggs. It takes an average 30 minutes to lay each clutch of eggs. The number of clutches each female lays varies greatly. After females are finished laying eggs, they cover them with sand and then depart, leaving the offspring to fend for themselves.

Average number of offspring 100-150

Range number of offspring: 50 to 250.

Average number of offspring: 100-150.

Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous ; sperm-storing

The female lays clutches of eggs and covers the eggs with sand after which there are no interactions.

Parental Investment: pre-hatching/birth (Protecting: Female)

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Evolution and Systematics

Functional Adaptations

Functional adaptation

Platelets reflect light: bobtail squid
 

Reflector platelets within squid chromatophores reflect light because they are nanofabricated photonic structures composed of proteins called reflectins.

   
  "The identification and characterization of the reflectins confirm that, although the majority of animal reflective tissues are composed of purine platelets, cephalopod reflector platelets are proteinaceous. Reflectins, a protein family with skewed amino acid compositions, repeating domains, and localized deposition, are thus far restricted to cephalopods. They represent a marked example of natural nanofabrication of photonic structures in these animals." (Crookes et al. 2004:237)

"A family of unusual proteins is deposited in flat, structural platelets  in reflective tissues of the squid Euprymna scolopes. These proteins,  which we have named reflectins, are encoded by at least six genes in  three subfamilies and have no reported homologs outside of squids.  Reflectins possess five repeating domains, which are highly conserved  among members of the family. The proteins have a very unusual  composition, with four relatively rare residues (tyrosine, methionine,  arginine, and tryptophan) comprising 57% of a reflectin, and several  common residues (alanine, isoleucine, leucine, and lysine) occurring in  none of the family members. These protein-based reflectors in squids  provide a marked example of nanofabrication in animal systems." (Crookes  et al. 2004:235)
  Learn more about this functional adaptation.
  • Crookes, W. J.; Ding, L. L.; Huang, Q. L.; Kimbell, J. R.; Horwitz, J.; McFall-Ngai, M. J. 2004. Reflectins: The Unusual Proteins of Squid Reflective Tissues. American Association for the Advancement of Science. 235-238 p.
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Euprymna scolopes

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 12 barcode sequences available from BOLD and GenBank.

Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.

See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

ACTTTATATTTTATTTTTGGTATCTGATCTGGTTTATTAGGGACCTCCTTA---AGTCTAATAATTCGAACTGAATTAGGTAAACCAGGTTCATTATTAAATGAT---GACCAACTATATAATGTAGTTGTAACCGCACACGGTTTTGTTATAATCTTCTTTTTAGTGATACCTATTATAATTGGCGGATTTGGTAACTGATTAGTTCCTTTAATA---TTAGGGGCCCCTGATATGGCTTTCCCTCGTATAAATAATATAAGATTTTGATTATTACCTCCATCACTCACATTACTTCTAGCCTCGTCAGCTGTAGAAAGAGGTGCAGGTACAGGATGGACTGTTTACCCTCCATTATCCAGAAACATTTCACATGCAGGACCTTCTGTAGATCTA---GCTATTTTTTCACTTCACTTAGCGGGAGTGTCCTCTATTTTAGGCGCAATTAACTTTATTACAACTATTATAAATATACGTTGAGAAGGGCTACAAATAGAACGGCTACCTTTATTTGTCTGATCAGTTTTTATTACAGCTATTTTACTACTTCTATCTTTACCTGTTTTAGCCGGG---GCAATTACAATACTATTAACTGATCGAAATTTTAATACTACTTTTTTTGACCCTAGAGGAGGGGGAGATCCTATTTTATATCAACACTTA------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------TTC
-- end --

Download FASTA File

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Statistics of barcoding coverage: Euprymna scolopes

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 12
Specimens with Barcodes: 12
Species With Barcodes: 1
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Conservation

Conservation Status

Euprymna scolopes is classified by IUCN as Data Deficient because of the uncertain status of its taxonomy (genus and species).

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

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IUCN Red List Assessment


Red List Category
DD
Data Deficient

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
Barratt, I. & Allcock, L.

Reviewer/s
Reid, A., Rogers, Alex & Bohm, M.

Contributor/s
Herdson, R. & Duncan, C.

Justification
Euprymna scolopes has been assessed as Data Deficient due to the persistence of taxonomic problems in the delineation of species in this genus making it impossible to determine whether it is threatened on a global scale.
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Population

Population
The population size of this species is unknown.

Population Trend
Unknown
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Threats

Major Threats
The threats to this species are unknown.
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Management

Conservation Actions

Conservation Actions
Further research is required to resolve taxonomic uncertainties and determine population trends and life history patterns of this species.
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Relevance to Humans and Ecosystems

Benefits

There are no known negative effects of Euprymna scolopes on humans.

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There is no information indicating any positive effects by Euprymna scolopes on humans.

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Wikipedia

Euprymna scolopes

Euprymna scolopes, also known as the Hawaiian Bobtail Squid, is a species of bobtail squid in the family Sepiolidae. It is native to the central Pacific Ocean, where it occurs in shallow coastal waters off the Hawaiian Islands and Midway Island.[1][2] The type specimen was collected off the Hawaiian Islands and is deposited at the National Museum of Natural History in Washington, D.C..[3]

E. scolopes grows to 30 millimetres (1.2 in) in mantle length.[1] Hatchlings weigh 0.005 grams (0.00018 oz) and mature in 80 days. Adults weigh up to 2.67 grams (0.094 oz).[4]

In the wild, E. scolopes feeds on species of shrimp, including Halocaridina rubra, Palaemon debilis, and Palaemon pacificus.[5] In the laboratory, E. scolopes has been reared on a varied diet of animals, including mysids (Anisomysis sp.), brine shrimp (Artemia salina), mosquitofish (Gambusia affinis), prawns (Leander debilis), and octopuses (Octopus cyanea).[6]

The Hawaiian Monk Seal (Monachus schauinslandi) preys on E. scolopes in northwestern Hawaiian waters.[7]

Symbiosis[edit]

E. scolopes lives in a symbiotic relationship with the bioluminescent bacteria Aliivibrio fischeri, which inhabits a special light organ in the squid's mantle. The bacteria are fed a sugar and amino acid solution by the squid and in return hide the squid's silhouette when viewed from below by matching the amount of light hitting the top of the mantle (counter-illumination) .[8] E. scolopes serves as a model organism for animal-bacterial symbiosis and its relationship with V. fischeri has been carefully studied.[9][10][11][12][13][14][15][16]

Acquisition[edit]

The bioluminescent bacterium, A. fischeri, is horizontally transmitted throughout the E. scolopes population. Hatchlings lack these necessary bacteria and must carefully select for them in a marine world saturated with other microorganisms.[17]

In order to effectively capture these cells, E. scolopes secretes mucus in response to peptidoglycan (a major cell wall component of bacteria).[18] The mucus inundates the ciliated fields in the immediate area around the 6 pores of the light organ and captures a large variety of bacteria. However, by some unknown mechanism, A. fischeri is able to out-compete other bacteria in the mucus.[18]

Adult Euprymna scolopes with scale.

As A. fischeri aggregate in the mucus, they must use their flagella to migrate through the pores and down into the ciliated ducts of the light organ and endure another barrage of host factors meant to ensure only A. fischeri colonization.[18] Besides the relentless host-derived current that forces motility-challenged bacteria out of the pores, a number of reactive oxygen species makes the environment unbearable.[18] Squid halide peroxidase is the main enzyme responsible for crafting this microbiocidal environment, using hydrogen peroxide as a substrate, but A. fischeri has evolved a brilliant counterattack. A. fischeri possesses a periplasmic catalase that captures hydrogen peroxide before it can be used by the squid halide peroxidase, thus inhibiting the enzyme indirectly.[18] Once through these ciliated ducts, A. fischeri swim on towards the antechamber, a large epithelial-lined space, and colonize the narrow epithelial crypts.[18]

The bacteria thrive on the host-derived amino acids and sugars in the antechamber and quickly fill the crypt spaces within 10 to 12 hours after hatching.[19]

Ongoing relationship[edit]

Every second a juvenile squid ventilates about 2.6 millilitres (0.092 imp fl oz; 0.088 US fl oz) of ambient seawater through its mantle cavity. Only a single V. fischeri cell, 1 millionth of the total volume, is present with each ventilation.[18]

The increased amino acids and sugars feed the metabolically demanding bioluminescence of the V. fischeri and in 12 hours the bioluminescence peaks and the juvenile squid is able to counter-illuminate less than a day after hatching.[19] Bioluminescence demands a substantial amount of energy from a bacterial cell. It’s estimated to demand 20% of a cell’s metabolic potential.[19]

Non-luminescent strains of V. fischeri would have a definite competitive advantage over the luminescent wild-type, however non-luminescent mutants are never found in the light organ of the E. scolopes.[19] In fact, experimental procedures have shown that removing the genes responsible for light production in V. fischeri drastically reduces colonization efficiency.[19] It may be that luminescent cells, with functioning luciferase, have a higher affinity for oxygen than for peroxidases, thereby negating the toxic effects of the peroxidases.[20] For this reason, bioluminescence is thought to have evolved as an ancient oxygen detoxification mechanism in bacteria.[20]

Venting[edit]

Despite all the effort that goes forth into obtaining luminescent V. fischeri, the host squid jettison most of the cells daily. This process, known as “venting”, is responsible for the disposal of up to 95% of V. fischeri in the light organ every morning at dawn.[21] The bacteria gain no benefit from this behavior and the upside for the squid itself is not clearly understood. One reasonable explanation points to the large energy expenditure in maintaining a colony of bioluminescent bacteria.[22]

During the day when the squid are inactive and hidden, bioluminescence is unnecessary and expelling the V. fischeri conserves energy. Another, more evolutionarily important, reason may be that daily venting ensures selection for V. fischeri that have evolved specificity for a particular host, but can survive outside of the light organ.[23]

Since V. fischeri are transmitted horizontally in E. scolopes, maintaining a stable population of them in the open ocean is essential in supplying future generations of squid with functioning light organs.

Light organ[edit]

The light organ has an electrical response when stimulated by light, which suggests that the organ functions as a photoreceptor that enables the host squid to respond to V. fischeri's luminescence.[24]

Extra-ocular vesicles collaborate with the eyes to monitor the down-welling light and light created from counter-illumination, so as the squid moves to various depths it can maintain the proper level of output light.[22] Acting on this information, the squid can then adjust the intensity of the bioluminescence by modifying the ink sac, which functions as a diaphragm around the light organ.[22] Furthermore, the light organ contains a network of unique reflector and lens tissues that help reflect and focus the light ventrally through the mantle.[22]

The light organ of embryonic and juvenile squids has a striking anatomical similarity to an eye and expresses several genes similar to those involved in eye development in mammalian embryos (e.g. eya, dac) which indicates that squid eyes and squid light organs may be formed using the same developmental "toolkit".[citation needed]

As the down-welling light increases or decreases, the squid is able to adjust luminescence accordingly, even over multiple cycles of light intensity.[22]

See also[edit]

References[edit]

  1. ^ a b Reid, A. & P. Jereb 2005. Family Sepiolidae. In: P. Jereb & C.F.E. Roper, eds. Cephalopods of the world. An annotated and illustrated catalogue of species known to date. Volume 1. Chambered nautiluses and sepioids (Nautilidae, Sepiidae, Sepiolidae, Sepiadariidae, Idiosepiidae and Spirulidae). FAO Species Catalogue for Fishery Purposes. No. 4, Vol. 1. Rome, FAO. pp. 153–203.
  2. ^ Countries' Exclusive Economic Zones with Euprymna scolopes[dead link]
  3. ^ Current Classification of Recent Cephalopoda
  4. ^ Wood, J.B. & R.K. O'Dor 2000. Do larger cephalopods live longer? Effects of temperature and phylogeny on interspecific comparisons of age and size at maturity.[dead link] PDF (134 KB) Marine Biology 136(1): 91.
  5. ^ Shears, J. 1988. The Use of a Sand-coat in Relation to Feeding and Diel Activity in the Sepiolid Squid Euprymna scolopes. R.T. Hanlon (ed.) Malacologia 29(1): 121-133.
  6. ^ Boletzky, S.v. & R.T. Hanlon. 1983. A Review of the Laboratory Maintenance, Rearing and Culture of Cephalopod Molluscs. Memoirs of the National Museum of Victoria: Proceedings of the Workshop on the Biology and Resource Potential of Cephalopods, Melbourne, Australia, 9-13 March, 1981, Roper, Clyde F.E., C.C. Lu and F.G. Hochberg, ed. 44: 147-187.
  7. ^ Goodman-Lowe, G.D. 1998. Diet of the Hawaiian monk seal (Monachus schauinslandi) from the northwestern Hawaiian islands during 1991 and 1994.[dead link] PDF (294 KB) Marine Biology 132: 535-546.
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