Making sense of systematics

neurobadger

Vampyroteuthis
Registered
#1
So I've got an internship at the Smithsonian doing cephalopod systematics.

One thing I've started to note about oegopsid squids, anyway, is the sheer difficulty that is keeping the characteristics of each family straight, because there are so many of them and they overlap.

What I've been able to find so far:

- An inverted-T mantle-locking apparatus is diagnostic of the Ommastrephidae
- A lazy-T mantle-locking apparatus is diagnostic of the Thysanoteuthidae
- A triangular mantle-locking apparatus is diagnostic of the Cycloteuthidae
- A nuchal-lock mantle-head fusion is diagnostic of the Cranchiidae

Everything else is woefully confusing right now.

Anyone got advice on how to identify everything else?
 

mucktopus

Haliphron Atlanticus
Staff member
Moderator
#2
Congratulations!! Working specifically with Mike Vecchione?

Identifying these characters will get easier with practice once you look at lots of specimens. I would recommend keeping the TOL website up and running, and spend a lot of time in the specimen room looking at representatives from the groups. But the bottom line it's true- using morphology to key out cephalopods is tough. They distort, shrink, break...it's not easy. Here's an interesting related (on octopuses) paper:

How useful are the recommended counts and indices in the systematics of the Octopodidae
(Mollusca: Cephalopoda) A. LOUISE ALLCOCK, JAN M. STRUGNELL and MARK P. JOHNSON
Biological Journal of the Linnean Society, 2008, 95, 205–218. With 4 figures
 

neurobadger

Vampyroteuthis
Registered
#3
mucktopus;179714 said:
Congratulations!! Working specifically with Mike Vecchione?
The very same, and Dr. Richard E. Young too! Very awesome people, and I am EXTREMELY lucky to be working with them.

Identifying these characters will get easier with practice once you look at lots of specimens. I would recommend keeping the TOL website up and running, and spend a lot of time in the specimen room looking at representatives from the groups. But the bottom line it's true- using morphology to key out cephalopods is tough. They distort, shrink, break...it's not easy.
I am actually doing some stuff with the TOL website. It's pretty fun - I'm helping refine some of the definitions on the keys. What I might try is finding two- to three- trait combinations that characterize a family, if any, if it doesn't have any one-trait diagnostic conditions.

Here's an interesting related (on octopuses) paper:

How useful are the recommended counts and indices in the systematics of the Octopodidae
(Mollusca: Cephalopoda) A. LOUISE ALLCOCK, JAN M. STRUGNELL and MARK P. JOHNSON
Biological Journal of the Linnean Society, 2008, 95, 205–218. With 4 figures
If I can dig it up, that'd be awesome. Perhaps you can email it to me if I PM my email address?
 

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