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Cephalopod studies

South Atlantic cruise on "RV Akademik Ioffe" 2009

31 October – 7 November

 

Cephalopod catches

Author: Kat Bolstad  

The dozen or so samples we have conducted so far have been especially rewarding for us “squiddy folk”.  Once the fish team have sorted out their material, we receive the rest of the IKMT catch and begin our cephalopod treasure hunt, watching carefully for the telltale iridescence of cephalopod eyes and digestive glands.  Some of the shrimps have so many anterior sensory structures that they look like squid arms, but we won’t be fooled.  And while it’s fun to look at the diverse crustaceans (krill, mysids, bright red deep-sea shrimp, Alien-esque ‘barrel shrimp’ of the genus Phronima that hollow out barrel-shaped salps and live inside them, round cartoon-like copepods and giant ostracods with mirror-like eyes), they pale in comparison to what we’re really here for.  

 

The ~200 specimens of squid and octopus we have collected to date include 27 species from 13 families, a very nice diversity.  Among these are many weird and wonderful taxa, about half associated with the scattering layer and half belonging to the general mesopelagic zone, with a few bathypelagic species thrown in for good measure.  There are baby argonauts, a family of octopus in which the male matures at a tiny 1–2 cm while the female grows much larger and builds a delicate white shell to brood her eggs.  There are many ‘glass’ squids, family Cranchiidae (same family as the colossal squid, Mesonychoteuthis hamiltoni), including Cranchia scabra, whose mantle is a transparent, perfect sphere, and covered with pointy tubercles that make it look like an inside-out golf ball, and Leachia sp., with its eyes out on stalks longer than its arms.  There are enoploteuthid squids with stunningly beautiful opalescent photophores (light organs) on their eyes, and some with hundreds of blue-green photophores scattered in tiny galaxies over their ventral sides.  There are deep-sea mastigoteuthid squids with long tentacles covered in tiny suckers, tiny brick-red squids of the genus Bathyteuthis (with round fins like little ears), and at least three species of gelatinous octopuses that are completely transparent except for the eyes and shiny, spindle-shaped digestive gland/liver.  We are in heaven.  (If you’re interested, you can find more photos and information on these species on the Tree of Life web project, www.tolweb.org.).

Photo: A.PerezPhoto: A. Perez

Special reports:

Benthic studies
Fish studies
Cephalopod studies

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