Why do cephalopods produce ink? And what's ink made of, anyway?

Cephalopods such as octopuses and squid have been known for their ink since antiquity. But what do we know about the evolution of ink and inking?Cephalopods, the group of molluscs that includes octopuses, cuttlefish, squids, ammonites, nautiluses and belemnites, are a weird bunch. Not only are they strange when anatomically compared to their shelled relatives like bivalves, snails and chitons but their evolution, physiology and behaviour makes them almost as interesting as vertebrates (I ’m kidding, they’re way more interesting).Despite there only being around 700 living species of cephalopods, biologically, they have evolved an array of adaptations that modern science is still only just unpicking. Neurologically, they are head (and shoulders if they had them) above all other invertebrate animals, sometimes called honourary vertebrates for their cognitive ability andpotential conciousness. They are famed for their ability to change colour, shape and size. Many of them are fast growing but short lived. They have adapted to live in the cold depths of the ocean, warm shallows and some species even ‘fly’. In terms of diversity, cephalopods include the egg case making argonauts, shelled nautiluses, venomous blue-ringed octopuses and enigmatic giants like the giant and colossal squid. Their anatomy has widely inspired art and design and research on their nervous system has lead to breakthrou ghs in our understanding of how the neurology of all organisms functions. However, ...
Source: Guardian Unlimited Science - Category: Science Authors: Tags: Biology Fossils Evolution Science Marine life Source Type: news