? Squid or Cuttlefish ?

cuttlegirl

Colossal Squid
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#2
That's a squid, but I could see how it could be hard to tell the difference, especially since the fins run the length of its mantle. The fisherman could tell by seeing if there was a gladius or cuttlebone. Also, the pupil would be different on a cuttlefish.
 
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DWhatley

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#3
I know we have an Atlantic squid that is often mistaken for a cuttlefish because of a similar fin arrangement and
I know the pen vs cuttlebone distinction but how do you tell squid from cuttle without cutting it open (ie from a photo)? In this case one could make an argument for what looks like an oval support OR a thin pen, depending on how you interpret the rigid part of the mantle.
 

CephBirk

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#4
I think cuttlegirl gave a good suggestion: look at the shape of the pupil. I know many cuttlefishes have a W-shaped pupil (as opposed to a squid's round pupil), but is that universal among cuttlefish? Could that be a defining characteristic to examine?
 

DWhatley

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#8
So this one must be australis where Sepioteuthis sepiadea is squid here that is often confused with a cuttlefish. Here (US East Coast) it is not difficult to decide since we don't have a native cuttle :roll: but Queensland (the source of the photo) would have both and the full skirt made me wonder how to tell from the picture (pupil not displayed well enough to make a call on shape). What about head to mantle connectivity? I note, though, that this one has a small external connection and I thought part of what separated squid from octopuses (apart from tentacles) is the internal vs external connection.
 

Taollan

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#9
Depends on what you consider W-shaped. It's not a good character to distinguish sepiids from myopsid squid in my opinion. Sepiella genus cuttlefish pupils are pretty U-shaped:


While some Sepioteuthis squid can have quite W-shaped pupils.
 

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