Anatomy of finfish and shellfish

Unit 13- Mollusca

13.3.11. Economic Importance of Cephalopods
Cephalopods are of use to man in various ways.
As food
Squids, cuttle-fish and devil-fish are popular articles of the human diet in the Oriental and the Mediter¬ranean countries. In China, Japan, India and Italy, they are sold in the markets for food. Sepia is abundant in the European waters; particularly in the Mediterranean Sea, where large quantities are used as food, either cooked or dried in open air. Small squids like Loligo, sometimes swim in large schools and are netted in great quantities. They are split, sun-dried and preserved for later use. The Red Indians, dwelling along the Pacific Coast in Canada and Alaska, are, said to use the devil-fish (Octopus) on many occasions In the Mediterranean and Oriental countries, South America and the South Pacific, boiled octopus is a much better known and more frequently eaten dish than boiled lobster.

Fig. 9- Octopus- The devil - fish

The pearly Nautilus (Nautilus poinpillus) is much prized as food by Pacific islanders.
Cephalopods are also an important source of food for other animals. Squids are gregarious and swim in vast numbers pursued by marine mammals and large fish which feed upon them. The giant squids (Architeuthis) of cold depths of Newfoundland and elsewhere are pelagic, spending their life swimming at various depths and eaten by sperm whales.
As bait
Squids make an excellent bait for marine fishes, especially for cod and are used by tons for this purpose in the United States. The cod, fishermen of the North Atlantic are well aware of the relation between the squids and the cod and express it by the laconic "Plenty squids, plenty cod". Small octopods are captured and used as bait by the line fishermen of Palk Bay, for their flesh is firm, not easily pulled off the hook, and of a tempting odour to fish sought after.
In arts and medicine
A rather odd and unexpected use for fossil cephalopods is found among the Red Indians of Montana and Wyoming. Their medicine men collect specimens of beautifully preserved fossil ammonoids from Cretaceous Strata, and keep them as' medicine". The internal calcareous shell of Sepia is the "cattle-bone" of the commercial world. It is used for various purpose, such as a medicine, a dentifrice, fine polishing agent, lime-supplying food for cage-birds like canaries, an agricultural fertilizer and for taking casts in metal work The cuttle-bones are collected on the Indian sea¬coasts, during monsoon, when they are drifted ashore in huge numbers.
The contents of the ink-sac of the cuttle-fish provide a rich brown pigment, called "Sepia", used by the artists. The original "India ink" was obtained from the ink of a cuttle-fish, Sepia cul'rara; today a certain brown finish of photographs is termed as sepia finish.
The shell of Nauzilus is also much used in the arts, and for many other useful purposes. It is a pretty object often thrown ashore during monsoon storms on the Indian coasts.
As predators
The cephalopods are all predaceous and carnivorous molluscs, devouring great numbers of fish, crusta¬ceans and other molluscs, and often are very destructive to the fisheries. Crabs are the favourite food of the octopods, but they also feed upon the bivalves, the organic debris of the sea bottom, and occasionally the fish. The giant squids (Archi¬teuthis princeps) of North Atlantic are the largest invertebrate animals with the body length of 15 meters excluding the arms. They are known to engage in battles with whales and devour their tongues by their sharp beaks.
In literature
The giant squids and octopuses have played a somewhat exaggerated role in popular literature. During the days of small sailing vessels, many sailors' tales were current describing the horrors of encounters with them. One such story pictures a huge squid dragging a small ship beneath the waves, after which it would 'grab the helpless sailors in its cruel, snake-like arms and crush them to death. But no authentic report of such an event is known to exist.