MAR-ECO Research Cruise

D, they're tiny! Tenths to hundredths of a millimeter across. The scale bars are 20 microns (0.02mm) in the first and third photos, and 0.5mm in the second.
Octopus suckers don't have hard sucker rings in them like squid suckers do (see attached photo borrowed from this site) - they're just flat, fleshy discs, so no pegs. Although someone just mentioned on this thread that there is some chitin in octo suckers as well.
 

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I did not think octos had them but I knew they were so tiny that I might not see them on the octos. Do the squid shed the lining of their suckers then? In the octos we see a small "skin" disk with a hole in the center but with these pegs, a single piece is unlikely.

Since the surfaces are so different, is this part of the diagnositic to determine squid vs octopus in some of the stranger species?
 
Not the pegs per se - just the presence/absence of sucker rings. I think Steve usually says in his talks that the only character that is guaranteed to differ between squid and octos is the sucker ring - there are octos with fins, and shells, and squid without tentacles, but every squid has sucker rings (or hooks) and no octo does.

Sucker rings are not shed routinely, but they will regrow (along with the new sucker) if the whole sucker is lost. Not sure whether a ring would regenerate in a sucker where just the ring had been lost (anyone know?). Hooks that are lost will go through the whole ontogenetic series too - regrowing as suckers and then transforming into hooks, assuming the remaining lifespan is long enough. Here's a regenerating tentacle club in Onykia robusta (D) and the opposite intact/undamaged club (C). Scale bars = 10mm (from memory).
 

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