For readers over 30 years old, IRL means "in real life".
Combfin squids in the family Chtenopterygidae are small, muscular, midwater squids that occupy tropical to subtropical waters probably at depths of 500-1000m during the day and near-surface waters at night. The posterior end of the mantle is broadly rounded. The fins are peculiar: they consist of muscular pillars called fin ribs, connected by thin membranes. The membranes are often torn in captured specimens, giving the fin the appearance of a comb; hence the family name. The fin extends nearly the full length of the mantle.
Every time I have caught Chtenopteryx they have been pretty beaten up. A few years ago, when E/V (Exploration Vessel) Nautilus was conducting ROV operations on Thessaloniki Mud Volcano in the Mediterranean, they recorded video of "a small squid" swimming near the ocean floor at about 1300 m. I finally got to see it recently and it was, as far as I know, the first in-situ observation of Chtenopteryx, probably C. sicula. As you can see from the frame grabs on the Tree of Life and the Nautilus Live video below, this strange squid looks even weirder when it is alive.
When first encountered, chromatophores (tiny pigment sacs) were expanded over the fin ribs, emphasizing these unusual structures. On the dorsal mantle above the digestive gland was a dark oval patch. Also, patterns of chromatophores on the lateral arms are displayed and then fade. The display of these patterns was surprising to cephalopod biologists and the purpose of the displays is unknown. Seeing it near bottom may seem unusual for a midwater squid, but it may just be at the deepest part of its daily vertical migration.
Comments