Genetic Differences in Cephalopods

Level_Head

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#1
This paper (free) talks about genetic differences between certain octopus species, particularly with respect to the one they're describing, O. insularis. It was very similar in appearance to the larger O. vulgaris, but turns out to be much further away in mitochondrial genes than expected:
http://www.demersais.furg.br/Files/2008.Leite.O.Insularis.J.of.Molluscan.Studies.pdf - 2006

The paper describes both the dorsal mantle white spots and arm crown spots in that species as distinct structures in common with O. vulgaris, but does not give much in the way of details.

In the case of the research discussed, they work on the usual, mitochondrial percentage differences. And they note that this can produce odd results; they express a hope for studies done with octopus nuclear DNA instead.
 

CaptFish

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#2
Genetic Differences in Cephalopods

A thread to discuss Genetic Differences in Cephalopods, and a place to post related material.
 

DWhatley

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#3
Thanks for the pdf reference Level_Head but not for the dorsal mantle white spot info :sagrin:. For whatever reason, I am determined to learn to ID our animals and when we have one that lives a normal life span unidentified it sticks in my mind. Penelope was one of these animals. I was sure it was not O.vulgaris because of the once seen ocellus and had guessed insularis. The paper gives a very good description of both the lines CaptFish saw AND the occassionally seen ocelli. Made my day!!

I am also going to reference this paper in the species section and quote the mantle description in the ppost.
 

Level_Head

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#4
Oh, the point of that mention was to echo the thought that it was a common feature of a great many species. I wasn't trying to suggest a species ID, just learn a little more about the cellular construction of those spots.

The paper had other interesting spots of its own, hence the post.
 

CaptFish

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#6
Do you think that Penelope was an insularis, then?
I don't. He was caught in the florida keys, and they are described as being from S.america. i am 99% convinced he was a vulgaris.
 

DWhatley

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#7
I DID but ...
After reading more of the paper and seeing several more confusing things (like both small and large eggs and both benthic and palegic young) I went back over the the PDF (sometimes books are easier) and realized that the amended description I was excited about was for the general vulgaris group and NOT insularis. Later in the paper it states there is no ocelli - bummed

However, with the warming waters seeing a South American animal would not be surprising.
 

DWhatley

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#8
GPO vs Rubescens

The Seattle aquarium posted an article, Which Octopus Are You Seeing? to differentiate between Enteroctopus dofleini and Octopus Rubescens.

The bullet points for Enteroctopus dofleini:
Weight:

Average 60lbs
Up to 150lbs
Arm Span:

Up to 20 feet across
Life Span:

3-5 years
Mating:

Terminal maters, both male and female will die after mating.
Female will lay 20,000 to 100,000 eggs and guard them till they hatch.
Males have a modified 3rd right arm used in mating (lacks sucker disks at the end of the arm).
Main Identifying Feature:

Giant Pacific Octopuses do not have "eyelashes", paddle like projections under their eyes.
Coloration:

Giant Pacific Octopuses are more red in color.
Skin Texture:

Giant Pacific Octopuses have paddle-shaped skin projections.
Common Den Types:

Rock piles, under rock ledges, tires, under downed pilings, old pipes.
Growth Rate:

1-2% of their body weight every day! Human example: gaining 2-4lbs a day.
Largest species of octopus in the world.


The bullet points for Enteroctopus dofleini:
Weight:

Max of 1.5lbs
Arm Span:

Up to 20 inches across
Life Span:

2 years
Mating:

Terminal maters, both male and female will die after mating.
Female will lay 20,000 to 30,000 eggs and guard them till they hatch.
Males have a modified 3rd right arm used in mating (lacks sucker disks at the end of the arm).
Main Identifying Feature:

Reds have "eyelashes" - three paddle like projections under their eyes called papillae (click here to see a picture).Coloration:

Reds are more brown/grey in color.
Skin Texture:

Reds have rounded skin projections.
Common Den Types:

Bottles, old barnacles, moon snail shells, under downed pilings.
 

DWhatley

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#9
A neurophylogenetic approach provides new insight to the evolution of Scaphopoda
Lauren H. Sumner-Rooney,Michael Schrödl,Eva Lodde-Bensch,David R. Lindberg, Martin Heß,
Gerard P. Brennan,Julia D. Sigwart 2015 (subscription)

[DWhatley] Interesting abstract proposing to add the scaphopods mollusca to the cephalopod grouping (genus?)

The position of scaphopods in molluscan phylogeny remains singularly contentious, with several sister relationships supported by morphological and phylogenomic data: Scaphopoda + Bivalvia (Diasoma), Scaphopoda + Cephalopoda (Variopoda), and Scaphopoda + Gastropoda. Nervous system architecture has contributed significant insights to reconstructing phylogeny in the Mollusca and other invertebrate groups, but a modern neurophylogenetic approach has not been applied to molluscs, hampered by a lack of clearly defined homologous characters that can be unequivocally compared across the radical body plan disparity among the living clades. We present the first three-dimensional reconstruction of the anterior nervous system of a scaphopod, Rhabdus rectius, using histological tomography. We also describe a new putative sensory organ, a paired and pigmented sensory mantle slit. This structure is restricted to our study species and not a general feature of scaphopods, but it forms an integral part of the description of the nervous system in R. rectius. It also highlights the potential utility of neuro-anatomical characters for multiple levels of phylogenetic inference beyond this study. This potential has not previously been exploited for the thorny problem of molluscan phylogeny. The neuroanatomy of scaphopods demonstrates a highly derived architecture that shares a number of key characters with the cephalopod nervous system, and supports a Scaphopoda + Cephalopoda grouping.
 

DWhatley

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#10
One step closer to understanding the chiroteuthid families in the Pacific Ocean
HE Braid, T Kubodera, KSR Bolstad 2017 (Marine Biodiversity subscription)

Abstract
The chiroteuthid families are a clade united morphologically by the absence of a primary tentacle club and the presence of a secondary tentacle club, comprising six families: the Chiroteuthidae, Mastigoteuthidae, Joubiniteuthidae, Promachoteuthidae, Batoteuthidae, and Magnapinnidae. This study provides new information on the group’s biodiversity in the Pacific Ocean and the interrelationships among these taxa and those from other locations, using fresh and ethanol-fixed specimens collected from Japan, Hawaii, California, and New Zealand from three institutions. Sequences were obtained for the DNA barcode region (cytochrome c oxidase subunit I), 16S rRNA, and 12S rRNA, nearly doubling the available sequences for the chiroteuthid families. Although the genera Chiroteuthis and Asperoteuthis did not resolve into monophyletic clades, our analysis did find support for the ‘C. veranyi group’ and the ‘C. picteti group’—identifying additional unnamed species in both—and the mastigoteuthid genera. A close relationship was found between Echinoteuthis atlantica and Mastigotragus pyrodes, with the latter reported herein for the first time from Japanese waters. The genus Idioteuthis appears to contain at least two species, making I.cordiformis’ a species complex in need of resolution. A catalogue of all specimens in this clade (representing 12 species across four families) registered in the collections of the National Museum of Nature and Science (NSMT) is also provided.
 

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