Modern writing ink is generally not made from squid. Cephalopods (squid, octopuses, cuttlefish) produce a dark fluid for defense, but this natural substance differs from synthetic writing inks. Their ink serves a different purpose and has a different chemical makeup than engineered writing inks.
Composition of Modern Writing Ink
Modern writing inks are complex mixtures tailored to the writing tool. Ballpoint pen inks are typically oil-based, containing pigments or dyes suspended in an oil solvent. Resins act as binders, helping the color adhere to paper. Lubricants, thickeners, and surfactants are often included to control viscosity, drying time, and flow.
Fountain pen inks are water-based and rely on dyes for color, as solid pigments can clog the pen’s narrow passages. These inks often contain humectants, such as glycerin, to regulate drying speed and prevent the nib from drying out. Surfactants are added to reduce surface tension, promoting better ink flow and preventing feathering. This combination allows modern inks to deliver consistent lines and dry efficiently.
The Biology and Chemistry of Cephalopod Ink
Cephalopod ink is a natural defense mechanism produced by marine animals like squid, octopuses, and cuttlefish. When threatened, they expel a cloud of dark ink to create a smokescreen, allowing escape. It is produced in a specialized ink gland, stored in an ink sac, and dispersed with a jet of water from the siphon.
The dark coloration of cephalopod ink comes mainly from melanin. Beyond melanin, the ink contains a complex mixture of organic and inorganic compounds, including proteins, polysaccharides, and trace elements. Different species produce varied ink colors: octopuses yield black, squid blue-black, and cuttlefish brown.
Real-World Applications and Common Misunderstandings
Cephalopod ink is commonly used in culinary arts, especially in Mediterranean and Japanese cuisines. It is valued for its deep black color and distinct briny, savory flavor, enhancing dishes like pasta, risotto, and seafood. Beyond food, it has been explored for potential in biomedical research due to bioactive compounds.
The misconception that writing ink is made from squid stems from historical uses and visual similarities. The term “sepia,” a reddish-brown color, derives from the Greek name for cuttlefish, whose ink was historically used as a pigment for drawing and painting. While some historical writing inks used natural pigments, including cuttlefish “sepia ink,” modern inks are predominantly synthetic. The dark, fluid appearance of both natural cephalopod ink and many writing inks contributes to this persistent, inaccurate association.