Lifespan - Octopus Optic Gland and More

DWhatley

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#1
A collection of links to articles and abstracts about octopus optic gland studies.


Optic glands and the state of the testis in Octopus - 1972 - abstract free, article subscription or pay for view

OPTIC GLAND IMPLANTS AND THEIR EFFECTS ON THE GONADS OF OCTOPUS - 1974 - Full PDF

Additional Lifespan Posts
Octopus senescence on the cellular level

Optic glands in octopuses

Seasonal Pattern to Octopus Deaths

Senescence The Beginning of the End

Study on Octopus Aging

Pre-senescence aging

Nervous control of reproduction in Octopus vulgaris: a new model
C Di Cristo - Invertebrate Neuroscience, 2013
Abstract


The classic study of Wells and Wells on the control of reproduction in Octopus demonstrated that the activity of the subpedunculate lobe of the brain and environmental illumination both inhibit the release of an unknown gonadotropin from the optic gland. This inhibitory control may be exerted by the neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide). It was later demonstrated that the olfactory lobe is also likely to be involved in the control of optic gland activity. The presence of gonadotropin-releasing hormone in the olfactory lobe suggested that it might exert an excitatory action on optic gland activity. Other neuropeptides have now been localised in the olfactory lobe: neuropeptide Y, galanin, corticotropin-releasing factor, Ala-Pro-Gly-Trp-NH2 (APGWamide), as well as steroidogenic enzymes and an oestrogen receptor orthologue. This supports the hypothesis that this lobe may also play a part in the control of reproduction in Octopus. The olfactory lobe receives distant chemical stimuli and also appears to be an integrative centre containing a variety of neuropeptides involved in controlling the onset of sexual maturation of Octopus, via the optic gland hormone. This review attempts to summarise current knowledge about the role of the olfactory lobe and optic gland in the control of sexual maturation in Octopus, in the light of new findings and in the context of molluscan comparative physiology.
 

Level_Head

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#2
You could make a story out of this ... ;)

This article downplays somewhat the effect on males. Later studies addressed that issue.

The optic glands are wired into the eyes to pick up lighting signals from the environment. Incidentally, that article indicates that changes in lighting condition -- such as the cues accidentally provided by a new tank's different light setup -- can be enough to trigger the optic gland's operation. This would result in sexual maturity and egg laying some weeks after the lighting change.

That sounds sadly familiar.
 

DWhatley

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#3
Do you have a link to the article about lighting, if it goes into detail about the kind of lighting that produced changes, I would very, very much like to read it.
 

Level_Head

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#4
From your second link (the full PDF):
One must therefore be wary of the effects of changing the apparent daylength, as is liable to happen when octopuses are kept in lidded tanks with artificial lighting in the laboratory. It is also necessary to be sure that changes in the state of the gonad do not arise from the changes in temperature or diet that are inevitable when the animals are brought in from the sea. Mangold & Boucher-Rodoni (1973), for example, have claimed that starvation tends to bring on early maturity in Eledone.
Both of these are suggestive, but the lighting seems to be a more universal trigger for optic glands.

In fact, trigger is probably the wrong word. Rather than wrong lighting triggering optic glands into action, it's "natural" lighting that, for a time, keeps the optic glands from being triggered. So any loss of that signal -- cutting nerves to the optic gland, covering or disabling the eyes of the octopus -- any of that removes the inhibition and the optic glands start their work to bring about sexual maturity and (in females) egg-laying quickly.

It is the change in length of daylight hours that is supposed to end the optic gland inhibition in the wild. So, it seems that the best approximation to the animal's normal lighting period might be the safest approach.

In fact, keeping the daytime period to simulate the time of year before sexual maturity begins might be the best approach. I haven't seen a paper that explicitly tries this, but it seems logical as an extending technique.
 

DWhatley

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#5
Brain Is Command Center for Aging - sound familiar?

OctopussyAZ posted a link on Facebook referencing several new science finds, this one was subtitled:

Inflammation in the hypothalamus may induce degeneration in tissues throughout the body

Reading the linked layman's summary in The Scientist I could not help but think of the similarities of the function of the hypothalamus and the optic gland in respect to aging and maturing.
 

DWhatley

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#6
Thoughts on Low Egg Production and Post Brood Longevity

I have wondered about the possibility of the number of eggs produced affects longevity after hatching (albeit, not an extensive extension) for the female octopus. It has occurred to me that something as simple as the eggs pushing on the digestive system might interfere with nutrition intake.

The thoughts started with my own observation with Trapper (O. mercatoris) who only produced 6 hatchlings and survived an additional 11 weeks.

The chierchiae octopus produces small clutches and is one of only two we know of that survives hatching and can produce an additional clutch.


The Island Bay Marine Education Center (Wellington, NZ) noted a similar occurrence:
A female octopus being returned to the sea received a special Mother's Day gift on Sunday - she had become an exception to the rule by surviving motherhood.

Most common octopus mothers do not survive the hatching process. Marine Education Centre director Judy Hutt said that was because female octopuses were such good mothers.

''She does very little other than care for her eggs. She doesn't move from them.''

The exhaustive process of keeping the eggs irrigated, clean and aerated usually means the mother starves to death once her babies have hatched.

Island Bay Marine Education Centre employee Jules Hodge was surprised at the mother octopus's extraordinary survival after her babies began hatching at the start of the month.

''It's the first time I've ever been aware of it. It is quite a big deal.''

The octopus was returned to the ocean on Sunday as a crowd of curious Wellingtonians looked on.

Mr Hodge said she now had a chance to either live out her life in the sea or die in her natural surroundings.

However, staff and volunteers have never seen a mother octopus look so healthy during the hatching process, so have high hopes she will live after all.

''What makes me think she may survive is the fact that she's eaten several crabs over the last few days. That isn't usually the case.

''They almost never eat anything the whole time they're looking after the eggs - not even when they're all hatched out,'' Ms Hutt said.

The female laid up to 400 eggs, a small batch in octopus terms, and all of them had hatched and relocated by Sunday.

The babies have been released into the Taputeranga Marine Reserve.

They will feed on microscopic zooplankton, and once matured will move on to molluscs, mussels, crab and rock lobster, although Mr Hodge said most would be eaten by larger creatures.

The prospect of baby octopuses made big news for Marine Education Centre followers online - the first Facebook update Ms Hutt posted on May 1 was seen by 8542 people.

Octopuses only enjoy temporary stays at the Bait House on The Esplanade. They're often brought in with injuries by local fishermen, and are nursed back to health before being returned to the sea.
 

DWhatley

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#7
[h=1]Coccidian infection may explain the differences in the life history of octopus host populations [/h] Lorena P. Storero, Maite A. Narvarte August 2013
[h=2]Highlights[/h]
  • We observed a high prevalence of coccidian parasites in Octopus tehuelchus populations.
  • Prevalence was similar between sexes, but varied between seasons and populations.
  • Prevalence increased with size.
  • Coccidian infection may explain the variability in host life-history traits between populations.
[h=2]Abstract[/h] The prevalence of coccidian parasites in three Octopus tehuelchus populations from San Matías Gulf (Patagonia, Argentina) is compared. The prevalence was similar between sexes, but varied between seasons (being highest during cold months) and sites. Islote Lobos had the highest prevalence (42.7–100%) followed by San Antonio Bay (0–66%) and El Fuerte (0–24.5%). Octopuses under 27 mm of dorsal mantle length showed a low prevalence (less than 50%), which increased with size. We hypothesize that the high prevalence of parasites, which affect the three populations differentially, could account for the observed variability in life-span and growth, size–frequency distributions, reproduction and densities of O. tehuelchus populations.
 

DWhatley

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#9
Hormonal inhibition of feeding and death in octopus: control by optic gland secretion Jerome Wodinsky 1977
Science 2 December 1977:
Vol. 198 no. 4320 pp. 948-951DOI:10.1126/science.198.4320.948 (subscription)


Note: This abstract declares that removal of the optic gland AFTER brooding slows reverses some of the senescence properties and the animal begins feeding and growing again. Prior studies noted that the removal must be done before sexual maturity.

Female Octopus hummelincki lays eggs, broods them, reduces its food intake, and dies after the young hatch. Removal of both optic glands after spawning results in cessation of broodiness, resumption of feeding, increased growth, and greatly extended life-span. Optic gland secretions may cause death of most cephalopods and may function to control population size.
 
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DWhatley

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A study on the optic glands of Sepioteuthis lessoniana from the Red Sea
Waheed M. Emam and Tarek G. Ali 2014 (pdf)

Work done on dead squid but includes an interesting note about removing O. vulgaris optic gland and implanting octopus and squid glands where the gland from other octopuses continued to develop and the squid optic gland did not.

Abstract: In the present work the optical glands of the reef squid Lessoniana lessoniana were are found in young
and adult individuals. They are paired small elongated organs that lie at the aboral end of the olfactory lobe, on a
level with the optic tract. Histological, the cells of the optical gland are large, with about 60 um in diameter and have
spherical nuclei (20 um in diameter). Their cytoplasm is coarsely granulated. Neurosecretory granules were seen in
cells of optical glands and stained with paraldehyde fuchsin. No distinct neuropil was observed in these glands and
these glands are rich in blood supply. The optic glands were found to be connected with optic nerve fibres to the
dorso-lateral lobes of the brain. The function of the optical glands of Sepioteuthis lessoniana was also discussed in
this study.
[Waheed M. Emam and Tarek G.Ali. A study on the optic glands of Sepioteuthis lessoniana from the Red Sea.
Life Sci J 2014;11(4):327-331]. (ISSN:1097-8135). http://www.lifesciencesite.com. 45
 

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#11
THE PARASITES OF CEPHALOPODS: A REVIEW
F. G. Hochbe 1983 (pdf)

Abstract
The literature and the status of our knowledge of the parasites of cephalopods are reviewed. Published and unpublished records of all hosts examined and parasites encountered are summarized in the text and a table. Of the approximately 650 species of cephalopods known, partial data on parasites are available for only about 150 species. Only two host species, Octopus vulgaris and Sepia officinalis, have been studied in detail and their total parasite loads documented. In addition to viruses, bacteria and fungi, three phyla of protists and six phyla of metazoans are recognized as symbionts of cephalopods. Several groups, such as the dicyemids, are known to be unique to the cephalopods. Many groups, especially the larval platyhelminths and nematodes, need to be properly associated with their corresponding adult forms. Viruses and fungi are potentially pathogenic to cephalopods and may be important in situations where cephalopods are reared, cultivated or maintained in captivity. Larval anisakid
nematodes are a potential human health problem and should be monitored in areas where squids are eaten raw.
 

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#12
Stylet weight as a proxy for age in a merobenthic octopus population
Abstract
An array of direct and indirect ageing methodologies have been trialled to rapidly, reliably and accurately determine the age of octopus species. The collective results of these efforts have largely led to compromising between time/cost and accuracy/precision. By combining direct and indirect methods, the suitability of stylet (internal shells) weight as a proxy for age was tested on Octopus (cf) tetricus, a merobenthic species (with paralarval stage) endemic to the west coast of Australia. Captive animals were injected with calcine to mark their stylets, confirming that stylet increments were formed daily. Stylet Increment Analysis (SIA) was applied to directly age 251 wild caught octopuses. Estimated age (days) and stylet weight (g) demonstrated a strong power curve relationship for both females and males (r2 = 0.94 and r2 = 0.88, respectively). Application of stylet weight as a proxy for age enabled a further 3280 octopuses to be aged. Maximum ages for females and males were 542 and 677 days, respectively. Age was found to be strongly related to mantle length for both sexes across all ages, indicating that wild merobenthic octopus populations may have stronger length–age relationships than captive growth studies suggest. Initial observations suggest that females may cease forming stylet increments at the onset of spawning.
 

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