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For a complete list of publications see Dr. James Wood's c.v.. Popular papers on cephalopods are here.
A preliminary investigation of the use of subcutaneous tagging in Caribbean reef squid Sepioteuthis sepioidea (Cephalopoda: Loliginidae).
S.E. Replingera and J.B. Wood
Bermuda Institute of Ocean Sciences, St. George's GE 01, Bermuda
This paper describes a new method developed to directly measure size and temperature specific growth rates of individual wild squid. Our tag and recapture method is complimentary to previously employed statolith aging methods but provides finer scale detail. The Caribbean reef squid, Sepioteuthis sepioidea, is an ideal model organism for field work on squid life-history as they live in shallow coastal areas and are accessible. These squid were tagged and monitored for tag retention and growth rates over a period of 56 days in the laboratory and 27 days in the field. A total of 103 squid were tagged, 10 in the laboratory and 93 in the field. Visible Implant Elastomer (VIE) tags and Visible Implant Alphanumeric (VI Alpha) tags were used during this experiment. None of the VI Alpha tags were retained in laboratory animals, but VIE tags remained visible for the duration of the laboratory study and were used in all field studies. The 10 recaptured squid weighed from 19.1 to 122.9 g with an average and standard deviation recapture weight of 56.9 ±35.5 g, compared to their original weights of 48.0 ±30.5 g. In the field, these squid had instantaneous growth rates of 1.19–3.10 with an average growth rate of 1.93 ± 0.71 at temperatures ranging from 19.5 to 23.7 °C.
Keywords: Squid; Tag; Growth; Sepioteuthis; VIE; Cephalopoda
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An introduction to Cephalopods (octopuses, squids, cuttlefish and Nautilus)
James Wood - Bermuda
Bermuda Biological Station
Cephalopods, the group containing octopuses, squids, and cuttlefish change color faster than a chameleon, have three hearts, are jet powered and are considered by many to be the most intelligent invertebrates. They have inspired legends since recorded history. Recently they have captured international attention as giant squid, the largest invertebrate in the world, have been photographed alive for the first time and baby giantsquid have also recently been captured. I will provide an introduction to these amazing mollusks and discuss their life cycles, behavior and ecology.
Estimating recent growth in the cuttlefish Sepia officinalis: are nucleic acid-based indicators for growth and condition the method of choice?
Frank Melzner,*, John W. Forsytheb, Phillip G. Leeb, James B. Wood, Uwe Piatkowskia, Catriona Clemmesena
A laboratory calibration study was undertaken with juvenile <i>Sepia officinalis</i> (80–85g initial wet weight) to investigate the effects of different food rations and different starving intervals on RNA/dry weight (DW) ratios and RNA/DNA ratios in cephalopod mantle muscle at two different temperatures. The digestive gland index was also used as an additional indicator of recent growth. High food rations and low temperature went along with high RNA/DW ratios and high RNA/DNA ratios. Starving resulted in a linear decline in growth performance and a concomitant decrease in RNA/DW and RNA/DNA ratio, with RNA/DNA ratios representing the growth data better. RNA/DNA ratios decreased faster at higher temperatures. A fluorimetric assay for nucleic acid analysis was optimized for cephalopod mantle tissues and yielded reproducible RNA/DNA ratios with a relative variance below 10%. Thus, it may be possible to use this estimator of recently encountered feeding regime for the evaluation of mortality rates of early teuthid paralarvae to eventually support stock management. Also, log relative digestive gland weight showed a strong relationship with starving time, but, surprisingly, not with temperature. Data from the two temperatures analyzed could be combined to form a common regression line of relative digestive gland index with starving time. This indicator for recent growth might be especially suitable for large specimens with a well-developed digestive gland.
Keywords: RNA/DNA; Sepia officinalis; Growth
Understanding octopus growth: patterns, variability and physiology
Semmens J.M., Pecl G.T., Villanueva R., Jouffre D., Sobrino I., Wood J.B. and P. R. Rigby
Marine and Freshwater Research
Octopuses are generally characterised by rapid non-asymptotic growth, with high individual variability. However, insitu octopus growth is not well understood. The lack of an ageing method has resulted in the majority of our understanding of octopus growth coming from laboratory studies. Despite not being applicable to cephalopods, Modal Progression Analysis (MPA) of length–frequency data is the most common method for examining in situ octopus growth. Recently, counting growth increments in beaks and vestigial shells, and quantifying lipofuscin in brain tissue, have all shown promise for the ageing octopus. Octopuses generally demonstrate two-phase growth in the laboratory, with physiological changes possibly associated with the switch between an initial rapid exponential phase and a slower power growth phase. Temperature and food ration and quality are key factors influencing the initial growth phase. Temperature, however, does not appear to affect the second phase in any consistent way, perhaps because maturity stage can influence the growth response. There may be basic differences in the mechanisms of octopus muscle growth compared with that of other cephalopods. Furthermore, higher relative maintenance energy expenditure, along with the low energy content of their prey, may account for the relatively slow growth of deep-sea octopuses compared to littoral species.
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Interspecific evaluation of octopus escape behavior
Wood J.B. and Anderson R.A.
Journal of Applied Animal Welfare Science
Octopuses are well known for their ability to escape enclosures. This behavior can be fatal and is therefore an animal welfare issue. Survey data from 38 participants, primarily scientists and public aquarists who work with octopuses, was obtained on 25 described species of octopus. This study demonstrates that the likeliness to escape is species specific (p=0.001). Husbandry techniques to keep captive octopuses contained are given. This first interspecific study of octopus escape behavior will allow readers to make informed species-specific husbandry choices.
Octopus senescence: the beginning of the end
Anderson R.A. Wood J.B. and Byrne R.A.
Journal of Applied Animal Welfare Science
Senescence is a normal stage of an octopus's life cycle that often occurs before death. Some of the following symptoms typify it: lack of feeding, retraction of skin around the eyes, uncoordinated movement, increased undirected activity, and white unhealing lesions on the body. There is inter- and intraspecific variability. Senescence is not a disease or a result of disease, although diseases can also be a symptom of it. Both males and females go through a senescent stage before dying, the males after mating, the females while brooding eggs and after the eggs hatch. There are many aspects of octopus senescence that have not yet been studied. Ecological implications of senescence are discussed.
Enrichment for Giant Pacific Octopuses: Happy as a clam?
Anderson R.A. and J.B. Wood
Journal of Applied Animal Welfare Science
Summary: The idea of environmental enrichment for invertebrates is new. This paper presents several arguments that in the absence of evidence, enrichment should be included for invertebrates such as octopuses. About the same time this paper was published, the first, and so far only, empirical evidence that enrichment is important for cephalopods was published by Dickel et al. 2000.
Introduction to CephBase www.cephbase.utmb.edu
Wood J.B., O'Dor R.K. and U. Piatkowski.
ACP-EU Fisheries Research Initiative
The combination of relational databases with the Internet allows for the exchange of information on a scale never before experienced. Database driven web sites can rapidly publish large sources of data on a platform accessible across geographic and political boundaries. This rapid and cost effective method of exchanging copious amounts of information will greatly help scientists understand the biocomplexity of natural systems. CephBase is an example of a taxon-specific web site powered by a relational database. CephBase serves data on all 703 extant cephalopod species. It is part of the "Census of Marine Life" effort that grew out of an U.S. initiative into a wider international undertaking in support of implementing documentation requirements of the Convention on Biological Diversity. The purpose of CephBase is to collect and provide information on life history, distribution, catch and taxonomic data on all living species of cephalopods (which includes octopuses, squids, cuttlefish and nautilus). Technical information on its current structure and access is discussed below together with an outlook on how cooperation between divergent biological databases could be facilitated.
Cephalopods: What makes them an ideal group for an Internet database
Piatkowskib U. and Wood J.B.
ACP-EU Fisheries Reseach Initiative
Living cephalopods include cuttlefishes, squids, octopuses and the chambered nautilus. There are 703 species described today, but the status of their systematics worldwide is decades behind that of other major marine taxa. They are quite distinct from fish not only in their morphology but also in their life history. Cephalopods have short life spans, fast growth rates (exponential when young), and they tend towards semelparity Cephalopod research is of interest and importance firstly because of the intrinsic value in understanding the complex biology and peculiar life cycles of these animals. While world-wide traditional fish stocks are decreasing the total world landings of all cephalopods have nearly doubled over the last decade (to 3.3 million tonnes in 1997). Cephalopods have gained an excellent market price and have become subject of global trade including developing countries. With an average value of US$ 2,100 per metric tonne, they gained a total market value of more than US$ 5.3 billion in 1989, which ranked them third after shrimp and tuna. Despite the increasing fishing pressure on cephalopods, basic knowledge of their biology and of management strategies of fished stocks lags behind that of most fish species. Hence, a widely accessible Internet database would certainly become a valuable tool to collect and provide comprehensive information to better understand and document major aspects of cephalopod biology and fishery.
Do larger cephalopods live longer? Effects of temperature and phylogeny on interspecific comparisons of age and size at maturity
Wood J.B. and O'Dor R.K.
2000 136(1): 91-99
The relationship between size and age at maturity in cephalopods is unresolved. The most recent interspecific comparison of size and age of cephalopods contradicts two previous studies by concluding that larger species do not live longer. This paper addresses the confounding effects of temperature and phylogeny while answering the question, “Do larger cephalopods live longer?”. To test this hypothesis, life-history data from 18 species of cephalopods, from five orders, with sizes at maturity spanning five orders of magnitude, were obtained from the literature. Without temperature consideration and with Nautilus spp. included in the sample, regression analysis suggests (r2 = 0.376, p = 0.007) that larger cephalopods take longer to reach maturity. Once temperature was controlled by using physiological time (degree-days), the coleoid cephalopods moved closer to the best fit line and the genus Nautilus became an outlier. When Nautilus was removed and time measured in degree-days, the relationship was very strong (r2 = 0.785, p < 0.001). We conclude that coleoid cephalopods achieve larger size by delaying maturity and that temperature, as well as phylogeny, must be considered when making interspecific comparisons.
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Reproduction and embryonic development time of Bathypolypus arcticus, a deep-sea octopod (Cephalopoda: Octopoda)
Wood J.B., Kenchington E. and O'Dor, R.K.
1998 39(1-2): 11-19
Mating, brooding, and embryonic development rate of Bathypolypus arcticus, a deep-sea octopod, are described.Live specimens of B. arcticus were collected in the Bay of Fundy, Canada and kept in a flow-through system in the lab. Two of the octopods laid and brooded viable eggs. Brooding and embryological development took over a year at average temperatures of 7.3 and 7.8°C. Brooding females ate occasionallyand only left their eggs shortly before dying. Hatchlingsweighed 208 +/- 17 (SD) mg from the first batch and 283 +/- 20 SD mgfrom the second batch. There was no evidence of multiple spawning.
Mating of B. arcticus was also observed. The usually smaller male sits upon the female, enveloping much of the female's mantle in his web, and he inserts his large ligula into her mantle. One or two large spermatophore are transferred by a combination of mantle pumping and arm groove peristalsis. A filmed mating sequence lasted 140 seconds.
Key words: Cephalopod, Octopoda, Octopodidae, Bathypolypus arcticus, deep-sea, mating, embryonic development, brooding.
2003 CIAC Meeting
Feb. 17-21, 2003.
CephSchool will be an online digital library designed to teach core concepts in life sciences. CephSchool will be supported by the data already existing in the CephBase relational database (www.cephbase.utmb.edu). This includes global scale coverage of all living cephalopods, 1,500 images, 144 videos, 5000 references, predator, prey and distribution data. The CephSchool site will devolve new content specifically for students and organized into eight arms (OCTOPUS!). These areas are: Online Laboratory Tour, Color Change in Cephalopods, Teachers Corner, Online Dissection Guide, Predators and Prey, Uses of Cephalopods, Students Corner and !links!. Cephalopods are ideal model organisms for teaching. Students are often drawn to them and they are colorful, active, interesting and different from vertebrates that are usually used. The site will facilitate access for students and teachers to the type and quality of information that is used by scientists
Ceph School: A pedagogic portal for teaching biological principles with cephalopod molluscs
Wood J.B. and Shaw C.
The National Science Foundation (NSF) National Science Digital Library (NSDL) all Projects Meeting
December 2-4, 2002.
The Ceph School team will create an online digital library suitable for teaching core concepts in life science in dramatic and dynamic ways. Cephalopods (octopus, squid, cuttlefish and nautilus) are ideal model organisms as they are colorful, active, interesting and different from most animals students typically encounter. We will empower students and teachers by catalyzing access to the type and quality of information that is used by leading scientists. Much of the Ceph School data is based on an already existing relational database, CephBase (www.cephbase.utmb.edu). This database was developed for scientists as part of the Census of Marine Life and has been featured in the journal Science twice. The Ceph School site will also contain a large amount of new content organized into eight arms (OCTOPUS!): Online Laboratory Tour, Color Change in Cephalopods, Teachers Corner, Online Dissection Guide, Predators and Prey, Uses of Cephalopods, Students Corner and !links!. Our team has a reputation for creating data rich, user friendly sites that are interoperable with partner projects; please feel free to contact me with suggestions and comments.
Understanding the past by looking at the present; using CephBase to examine behavior and selection in coleoid cephalopods.
Wood J.B., Byrne R.A. and Monks N.
Coleoid cephalopods through time: neontological approaches to their palaeobiology in the light of the fossil record
Free University of Berlin, Germany
September 16 - 19, 2002.
Coleoid cephalopods leave a challengingly fossil record. Basal Coleoidea such as belemnites are common but were an evolutionary dead end. Although cuttlefish and Spirula-group cephalopods left a record (Monks and Wells 2000), squid and octopuses do not have calcified shells that fossilize easily (Doyle 1993). This lack of hard body parts in these major extant taxa makes theorizing on cephalopod anatomy, behavior, life history and evolution especially difficult for paleontologists.
For researchers of extant cephalopods, the preservation of animals is very useful for many areas of research, for example taxonomy. However, preservation destroys much information, such as the range of appearance and behavior. An additional challenge is that much of the diversity of modern Coleoidea occurs in the deep-sea and these species are poorly studied (Wood 2000).
Perhaps more than any other animal, cephalopods are able to change color, texture and shape. These are used in avoiding predation and for inter- and intra- specific communication. The most obvious component of appearance is color. Cephalopods use specialized cells, chromatophores, iridophores and leucophores, to change color (Messenger 2001). They can also raise and lower papillae and change skin texture. They have few to no hard internal structures in their body and this allows them to change posture. They also use combinations of the above with jet escape and ink decoys, as did Jurassic Vampyromorphs and Belemnites (Monks and Palmer 2002). All of these components are used together so the animal's color, shape, posture, texture and location can rapidly change from one moment to the next (Hanlon and Messenger 1996).
All this information about cephalopod displays and behavior can be stored in images. Prohibitive costs of publishing color images in traditional media otherwise limits studies of the role of behavior in cephalopod evolution.
New technology allows for the inexpensive collection, storage and publication of visual data. CephBase (www.cephbase.utmb.edu), an online relational database, can help us do this. There are over 1000 images of extant cephalopods that can be used to examine the range of appearance between and within species. Each image is documented with species, location and sex, size and depth if known. It is readily accessible across geopolitical boarders at any time (Wood et al. 2000).
CephBase not only contains images of a wide variety of cephalopods, but also addresses cephalopod ecology with a database of over 500 predation records. These predators are marine mammals, birds, fish and other cephalopods. Hypotheses such as the "Packard scenario" (Packard 1972) and the "Modified Packard scenario" (Aronson 1991) predominately feature predation from vertebrates as the major driving force of cephalopod evolution. Studies of extant cephalopods show that predation has a major effect on population density and behavior. Octopus density is inversely correlated with teleost density (Aronson 1991) and according to Mather and O'Dor (1991) octopuses do not forage to fully maximize growth due to predation risk from visual predators.
The repertoire of changes in appearance is species specific, although some patterns are similar across taxa. In other words, the development of color, texture and shape components are vital for avoiding predators and therefore critical for evolution and natural selection.
CephBase can be used to help bridge the gap between paleontologists and researchers studying modern cephalopods. In addition to the tools outlined above all paleontologists that work on cephalopods are invited to become listed in the International Directory of Cephalopod Workers (please see us with your contact information). We would also like to create a new section on CephBase with links to paleontological sites and encourage conference attendees with such sites to contact us. Furthermore, we wish to let the paleontological community know that there are two cephalopod list servers, CephList and FastMol, which they are welcome to join.
Aronson (1991) Ecology, paleobiology and evolutionary constraint in the octopus. Bul of Mar Sci 49(1-2): 245-255
Doyle P (1993) Mollusca: Cephalopoda (Coleoidea). 229-236, In: Benton M. J. "The Fossil Record 2" Chapman & Hall, London
Hanlon RT, Messenger JB (1996) Cephalopod behaviour. University Press, Cambridge
Mather JA, O'Dor RK (1991) Foraging strategies and predation risk shape the natural history of juvenile Octopus vulgaris. Bul of Mar Sci 49(1-2): 256-269
Messenger JB (2001) Cephalopod chromatophores: neurobiology and natural history. Bio Rev 76: 473-528
Monks N, Palmer CP (2002) Ammonites. Natural History Museum & Smithsonian Institution
Monks N, Wells S (2000) A new record of the Eocene coleoid Spirulirostra anomala (Mollusca: Cephalopoda) and its relationships to modern Spirula. Tert Res 19: 47-52
Packard A (1972) Cephalopods and fish: the limits of convergence. Bio Rev 47: 241-307
Wood JB (2000) The natural history of Bathypolypus arcticus (Prosch), a deep-sea octopus. PhD Thesis, Dalhousie University
Wood JB, Day CL, O'Dor RK (2000) CephBase: testing ideas for cephalopod and other species-level databases. Oceanogr 13(3): 14-20
Squid say it with skin: a graphical model for skin displays in Carribbean Reef Squid (Sepioteuthis sepioidea)
Byrne R.A., Griebel U., Wood J.B. and Mather J.A.
Coleoid cephalopods through time: neontological approaches to their palaeobiology in the light of the fossil record
Free University of Berlin, Germany
September 16 - 19, 2002.
A graphical model to express 'squiddish', visual skin displays in reef squid Sepioteutis sepioidea, was developed. It was created and refined as a result of a field study off the Caribbean island, Bonaire, to systematize the repertoire of patterns of an ethogram of the species (Griebel 2002).
Moynihan (1982, 1985) was among the first to recognize and describe the amazing variety of body patterns that S. sepioidea produces. This species belongs to the more "social" loliginids and is thus likely to have more sophisticated communication abilities than solitary species. S. sepioidea lives in a complex environment, coral reefs, which evokes a rich pattern repertoire (Hanlon and Messenger 1996).
Squid communication is composed of visual components on their body and postures (Hanlon and Messenger 1996). These components can be turned on and off and are grouped together for complex inter and intraspecific communication. To accomplish this, squid have a chromatophore system that is directly controlled by the brain and they can change color and position rapidly (Messenger 2001). In addition to this, they use iridophores and leucophores to differentially reflect light (Hanlon and Messenger 1996).
It has been suggested that these highly flexible skin displays have evolved primarily for camouflage and predator-avoidance purposes (Packard 1972), matching the receiver characteristics of the vertebrate eye. The flexibility of the chromatophore system and its speed of change lend themself ideally to communication purposes, therefore it is not surprising that cephalopods evolved complex communication signals with this system.
Like squid skin patterns, our graphical model is composed of components. It was created in Photoshop 5.5 and consists of a dorsal and a lateral view of a squid. These two shapes can be filled with components for displays by turning combinations of the multiple layers in the photoshop program on and off. Components are divided into basic background colors and areas on the body which they overlay distinct patterns. Basic background colors in the model are pale, white, yellow, gold, brown and black. Other components are horizontal stripes, vertical bars and dots, as well as zebras and mottles. A set of arm postures accompanies the patterns.
This model creates displays shown by squid by clicking together combinations of layers in the photoshop program. It demonstrates an assortment of intraspecific displays of S. sepioidea, including variations in patterns between males and females and across different age groups, as well as interspecific displays such as camouflage patterns.
This model, will be made available for downloading via CephBase (www.cephbase.utmb.edu). It will help researchers catalogue the full range of displays of S. sepioidea and also can establish consistent terminology for the components and patterns of these squid. This tool can be easily modified or added to as changes and new patterns are observed. Finally it can also be used as a first step to set up models for other species to compare skin displays across species or different 'local dialects' of the same species of cephalopods.
Griebel U, Byrne RA, Mather JA (2002) Squid skin flicks. presented at ABS Meeting, Bloomington, Illinois Hanlon RT, Messenger JB (1996) Cephalopod behavior. University Press, Cambridge Messenger JB (2001) Cephalopod chromatophores: neurobiology and natural history. Bio Rev 76: 473-528 Moynihan M, Rodaniche AF (1982) The behaviour and natural history of the Carribean reef squid Sepioteuthis sepioidea. Adv. in Ethol., 25. Packard A (1972) Cephalopods and fish: the limits of convergence. Bio Rev 47: 241-307
CephBase II - a new tool for quantifying, cataloging and investigating cephalopod biodiversity
August 19-25 2001.
Online databases allow scientists to collect large amounts of biodiversity, life history, behavior and ecological information in one place. Scientific information has traditionally been held in journal articles that are often difficult to obtain. Additionally this traditional media has some very real limits on the amount and type of data that can be presented. Simply collecting and displaying information from many articles, such as species distribution, is often enough to see new patterns. When we take this information and combine it with what we know about the environment such as bottom type, currents, primary production, temperature and other parameters, we really tap into the power of databases. Putting this data online acts as a catalyst for scientific productivity. It allows many workers from a variety of backgrounds and across geopolitical borders easy access to large amounts of information. Much like a microscope allowed us to see what was always there, this emerging technology allows us to look at something that already existed in new and exciting ways.
CephBase www.cephbase.utmb.edu is an online relational database that catalogs the biodiversity of all living cephalopods in one easy to access place. It contains distribution, predator, prey and image data plus over 3,000 references for this productive class of mollusks. A demonstration of the main features of CephBase will be given.
CephBase is part of the Census of Marine Life, an international program initiated by the Sloan Foundation to explain the diversity, distribution and abundance of marine life. CephBase is supported by the National Oceanographic Partnership Program.
How slow can they grow? Not all coleoid cephalopods live fast and die young.
Wood J.B. and O'Dor R.K.
Cephalopod International Advisory Council conference, GIS and database workshop
July 3-4, 2000
Coleoid cephalopods are thought to have high growth rates and short life spans. While this generalization holds for the traditionally studied shallow-water, near-shore species, it does not for at least some deep-sea species. The deep-sea is the largest habitat on earth and it contains many species of cephalopods. From Architeuthis to Bathypolypus, deep-sea cephalopods are important prey for marine mammals like sperm whales to commercially important fish like cod. In comparison to shallow water cephalopods, I have found very low growth rates, long estimated life spans, low fecundity, extended brooding period, low activity, starvation resistance, and lower quality diets for Bathypolypus arcticus, a benthic deep-sea octopus. Low temperatures do not fully explain these differences. These traits point to a strategy that differs from the live fast and die young life cycle typical of coleoid cephalopods. Instead, these deep-sea octopuses seem to have traits that suggest relaxed predation pressure (low fecundity, long time to maturity, no use of lairs) but increased food limitations (large hatchlings that can survive a median of 57 days without food, reduced activity, ingestion of low quality prey like brittle star arms). These traits have important ecological ramifications as they point to much lower production and population recovery rates than for traditionally studied near-shore species.
What is CephBase?
Wood J.B., Day C.L. and O'Dor R.K.
International Council for the Exploration of the Sea (ICES)
CephBase (www.cephbase.dal.ca) is an interactive database-driven web site currently being developed at Dalhousie University, Halifax, Canada. It is designed to compile and organize a wide range of data on all known species of Class Cephalopoda. Although it has only been up for a few weeks and has not yet been announced publicly, CephBase already contains searchable taxonomic data on every living cephalopod. The CephBase team hopes to have fisheries catch data, life history traits, distribution, and other cephalopod information online in the future. To help us reach this goal, we are asking ICES as a whole as well as individual cephalopod workers for assistance.
First lab rearing of Bathypolypus arcticus, a deep-seaoctopus
Wood J.B., Brown S. and O'Dor R.
Northeast Regional Animal Behavior Meeting
October 3-5, 1997
Observing the behavior of deep-sea cephalopods in wild is difficult. However, before they can be maintained successfully in the lab, their feeding requirements must be determined. The purpose ofthis study was to examine the effect of 5 different food types on the growth and survival of Bathypolypus arcticus. At hatching 153 B.arcticuswere randomly assigned to one of five feeding treatments: liveCorophiumvolutator, live Gammarus spp, frozen Gammarus spp,frozen haddock(Melanogrammus aeglefinus) and brittle star (Ophiopholisaculeata) arms. Octopuses were individually housed, kept at 8.3 C and weighed monthly. The octopuses fed live crustaceans showed positive growth rates and survived to the end of the experiment while the remaining treatments showed zero ornegative growth rates and low survival.
From the tropics to the arctic(us) - the importance of temperature in testing life history hypotheses
Wood J.B. and O'Dor, R.K.
Life history theory is concerned with fitness, trade-offs, adaptation and constraints. By studying the diversity of life history patterns that occur in nature, we can begin to see patterns and trade-offs that offer insights into natural selection. From a practical point of view, an understanding of life history traits such as growth rate, age at maturity, fecundity, reproductive strategy, mortality schedule and lifespan are necessary for effective fisheries management. In 1987 Calow published a paper that quantitatively tested avariety of life history hypotheses using a data set that consisted of representatives of four major groups of cephalopods. One of his conclusions was that large cephalopods do not have longer life spans which suggests that larger cephalopods grow faster. Calow also found a weak (r2=0.222) but significant (p=0.05) positive correlation between egg volume and development time.
We used a more comprehensive data set to test Calow's conclusions that large cephalopods grow faster and that there is a weak but significant positive correlation between hatchling size and development time. We use both standard time (days) and physiological time (degree days) in the analysis to demonstrate the importance of controlling for temperature when studying life history traits with a time component.
We found no evidence that large cephalopods grow faster (p >> 0.05) using either standard time or physiological time. After controlling for temperature, we found that cephalopods achieve larger size by living longer (p < 0.005). As with Calow's analysis, the results were not significant when using standard time. Both standard time and physiological time tests indicated a significant positive correlation (p < 0.005) between hatchling size and development time. However, the p-value was lower and the correlation stronger in the temperature corrected analysis (r2=0.869 for physiological time, r2=0.667 for standard time).
Reproduction of Bathypolypus arcticus, a deep-sea octopod (Cephalopoda: Octopoda)
Wood J.B., Kenchington E. and O'Dor, R. K.
Canadian Society of Zoologists
Bathypolypus arcticus, a small deep-sea octopod that rarely exceeds 200 g, is the most common octopus found off the east coast of Canada. Live specimens of B. arcticus were collected in the Bay of Fundy, Canada and kept in a flow-through system. Two of the octopuses brooded fertile eggs for over 400 days at 7.3 and 7.8°C. Mating and hatching was also observed and filmed for the first time. Unique data on mating, brooding, embryonic development times, and hatching of this cold-water octopod will be compared to what is known or postulated about other octopods.
Reproduction de Bathypolypus arcticus, un poulpe pelagien (Cephalopoda: Octopoda). Bathypolypus arcticus, un octopode des eaux profondes est d'unetaille trŠs petite, rarement epassant 200g. C'est la poulpe laplus commune des eaux de la co“te est du Canada. Des secimensvivants de B. arcticus ont ete receuillis de la Baie de Fundy,Canada, et maintenus dans un systŠme... ‚ coulement continu. Deux poulpes ont couves des oeufs fertiles pendant 400 jours... 7.3 et 7.8°C. L'appariement et l'eclosion des oeufs a ete observe etfilme pour la premiŠre fois. De l'information unique surl'appariement, la couvaison, la duree du development embrionique etl'eclosion des oeufs de ce poulpe des eaux froides est compares auxfaits connus et postules pour d'autres octopodes.
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The Cephalopod Page (TCP), © Copyright 1995-2016, was created and is maintained by Dr. James B. Wood, Associate Director of the Waikiki Aquarium which is part of the University of Hawaii. Please see the FAQs page for cephalopod questions, Marine Invertebrates of Bermuda for information on other invertebrates, and MarineBio.org and the Census of Marine Life for general information on marine biology.