With a maximum length of 74 cm (mantle length 188 mm) and weight of up to 1.4 kg, the musky octopus is a medium-sized octopus species (on average, they are 40 cm long). It has a narrow head with protruding eyes and relatively short arms, which only extend to two-and-a-half to three times the length of the mantle. It has approximately 120 suckers that stand in a single row on each of its arms, unlike most octopus species. Its arms (tentacles) are connected to one another by a stretchable umbrella-like, thin and transparent membrane (web) along the first third of their length at the base of the head. The movements of the arms and suckers are ‘autonomously’ controlled by countless nerves and ganglia, making them quite independent of control from the brain. The octopus likes to move its tentacles freely in all directions. The sensitive gripping and tasting organs are as dexterous as an elephant’s trunk and as versatile as a Swiss army knife.
Musky octopus and horned octopus are related species
The musky octopus resembles the better-known common octopus (Octopus vulgaris) in its appearance and important anatomical features, however it can clearly be distinguished from the common octopus by its single row of suckers on its tentacles. This is somewhat more difficult with the horned octopus (Eledone cirrhosa), which is closely related to Eledone moschata, as both related species have a grey-brown body colouration with dark brown or black flecks on their back. However, while musky octopuses have very smooth skin, the skin of the horned octopus is noticeably rough and warty. The surest way to distinguish between these animals while fresh, however, is to rely on one’s nose. The musky octopus emits an intense musky odour as it is taken out of the water immediately after it is caught, which is produced by glands in its skin. This is referred to in its scientific name by ‘moschata’, which derives from the Latin word ‘moschatus’ meaning ‘musky fragrance’. In Italy this small octopus species is also known as moscardino, polpo moscato or mughetto due to its distinct aroma. However, it has still not been precisely explained what the smell is for and what biological function it has.
Another difference between the two Eledone species is their lifestyles. While the horned octopus (E. Cirrhosa) is more likely to be found in areas of deeper waters between 180 and 450 m, the musky octopus (E. Moschata) prefers shallower coastal zones with a depth of between 8 and 200 m, with the greatest individual densities found between 50 and 80 metres. The musky octopus is active at dusk and at night and likes to dig into sandy or muddy ground during the day to escape its predators, which include larger squid in addition to conger eels and grouper. This offers little protection against dolphins and sharks, however, who can locate the octopuses hiding in sediment using echolocation or electrical sense organs (‘ampullae of Lorenzini’). On the other hand, these little octopuses are voracious hunters themselves. Thanks to their highly sensitive eyes (‘camera eyes’), their photosensitive skin and their ability to quickly and deceptively change their shape and colour to match their surroundings, they make very successful predators. They cleverly vary their hunting techniques: they can ambush their prey, pursue it or overpower it with a sudden pounce. They are helped in this by their ‘jet engine’, a siphon that can be adjusted to point in any direction, from which they can suddenly eject water in order to attack or to flee. The octopus will eat anything it can catch: crabs and other crustaceans, molluscs, snails and occasionally also small fish such as sardines, anchovies or red mullet. Even animals that are larger than the musky octopus can become its prey. The octopus holds its prey skilfully with its catching arms and then breaks off bite-sized pieces with its hard, beak-like mouth organs or grinds it up with its toothed tongue (‘radula’). Even hard-shelled molluscs and heavily armoured crustaceans are not safe from its sharp beak.
The life of an octopus ends after its first reproduction
Musky octopuses are loners with opportunistic behaviours, who can adapt to extreme living conditions and cope with almost any ecological and climatic conditions without problems. If its preferred prey is scarce, it can also eat eels or cannibalise smaller members of its own species.
Because octopuses do not have any rigid body structures except for their hard ‘parrot beak’, they can change their shape in a very supple and elastic way, which makes it possible for them to pass through very narrow fissures and openings. Like all cephalopods, the musky octopus secretes an inky black liquid when in danger, which is produced and stored in a sac in its body. The animal is more easily able to flee thanks to the cover provided by the ink, because it irritates its attacker and obstructs its vision. The ink is also used in confrontations with rivals during breeding periods.
Musky octopuses grow very rapidly and can put on one to two percent of their body weight per day when they are young. This is a necessity, because octopuses seldom live longer than two years, and usually no more than a few weeks after reproducing. Eledone moschata mostly reproduces during the winter and spring months. The proportion of sexually mature animals in many regions of the Mediterranean is especially high in January and February. In the Southern Adriatic, sexually mature males can be found all year round, mostly from October to May, but the main maturity period of the females is shorter and restricted to the spring. At this time the mantles of the females measure at least nine centimetres, and their oocytes should have reached a length of 15 mm. Like almost all octopuses, musky octopus males use their third right tentacle to fertilise, which is known as the ‘hectocotylus’. This arm is only 85 to 90% as long as the other tentacles and ends in a spoon-shaped flattened tip (ligula) that has a depression on the inside in which a semen capsule (spermatophore) is stored. This structure is also referred to as the hectocotylus, which derives from the Ancient Greek words hekatón (hundred) and kótulos, meaning bowl or saucer. During mating, the male wraps its tentacles around its selected partner, pushes its hectocotylus into the mantle hole and leaves a spermatophore in the female’s fallopian tube. It is often stored there for a time until the oocytes are fully mature, Only when it splits open are the sperm free to fertilise the egg.
Depending on their size, females will produce approximately 400 to 500 eggs, which are some 5 mm thick and 15 mm long. They are attached in clusters of 3 to 10 eggs each to a solid substrate, often in rock crevices, under stones or in large mollusc shells. There they hang on short stalks that are connected to each other at the base. Separate attachment in small groups guarantees a sufficient oxygen supply for the embryos growing in the eggs. Also, the eggs have more space and are not too constricted if they swell up shortly after being laid before the gelatin capsules of the eggshells finally harden. The octopus offspring develop in the eggs in the clutch, which the female watches over, cares for and guards devotedly. They do not go through a typical larval stage and they already look like miniature versions of their parents as soon as they hatch. They are fully independent from day one and can survive by themselves. Because the older animals die soon after their reproducing period, octopuses do not form any close parent-child relationships and cannot transfer any of their learned skills to the next generation. Their offspring must therefore always learn everything again for themselves from scratch.
Wide range of fishing methods
Because octopuses are known as the ‘smartest’ of all the molluscs, with an intelligence level said to be comparable to that of rats, special catching methods are required in order to outwit them. Musky octopuses prefer to live in shallower waters and come closer to the shore during their nightly hunts. However, due to increasing noise, heavy shipping traffic and other disruptive factors, they tend to be driven into deeper waters. In addition, the animals have become relatively rare in areas where they are regularly intensively fished. All of these factors make traditional methods of catching individual octopuses with spears and harpoons significantly more difficult. Nevertheless there continue to be large numbers of hobby divers who hunt these molluscs in this ‘archaic’ way. Harpoon catching requires relatively little technical equipment, but all the more skill and experience, because the octopuses are difficult to find and they also clamp onto the substrate after being hit, meaning additional tools such as a hook are sometimes required in order to prise them off. However, the punctures in the body negatively affect the quality of the octopus. This is not a problem for private consumption of the catch, but it reduces the commercial retail value.
It is simpler, but requires greater technical expenditure, to catch them with traps, which come in many different sizes and designs. A classic method that has probably been in existence for centuries is to use simple clay pots in the shape of a jug, which the octopuses love to hide in. Bait is not required for this method, as the octopuses hide in the pots for protection rather than food. If they like the accommodation offered to them, the traps are occupied soon after they are set. The net or basket traps, that are designed similarly to lobster pots, are based on this principle. They are provided with attractive bait – mostly fresh raw fish – which entices the octopus into the trap. It usually enters from above through a small opening and can then no longer find its way out.
The traps can be pulled up to the surface on a daily basis by means of a headline to collect the catch and restock the trap with bait. In some regions, fish traps are also used for octopuses. The traps have the advantage that the animals are not injured or damaged and are therefore more marketable. Because the octopuses are still alive, animals that are too small can also be released back into the sea unharmed.
However, a particularly productive method is bottom trawling, although it is subject to certain regional and seasonal fluctuations. Because octopuses are solitary animals and do not live in large groups, there is no targeted fishing, the animals usually only end up in nets as a welcome bycatch. This is the reason why catching them requires a good knowledge of the location and sufficient experience, as the habitats of the octopus vary according to region, water depth and the time of year. If the conditions are right however, the towing haul can very frequently include individual animals. A few decades ago, for example, octopus catches of 50 kg per hour were possible in the Northern Adriatic. The proportion of musky octopus was usually between 10 and 50 percent at that time. In the Southern Adriatic off the coast of Montenegro, this octopus species made up a third of the cephalopod biomass. From the 1970s to the beginning of this century, the annual catch quantity in the Adriatic region fluctuated without any clearly discernible trend, but since then fishers, at least on a regional basis, have been complaining of a slow but steady decline in catches. Due to the patchy data available, however, there are many locations where clear evidence of overfishing is lacking, but is likely.
Octopus is a must-have on the Mediterranean menu
The relationship of humans to the musky octopus is of a mainly commercial nature and is shaped by the culinary use of these molluscs. They are not considered quite as tasty as the common octopus (Octopus vulgaris) and their commercial value is also only half as high, but they have great importance for local fisheries almost everywhere in the Mediterranean. Particularly in the Adriatic, as well as on the North African, Spanish, and Portuguese coasts. In Italian gastronomy, it is frequently offered as moscardino muschiato or moscardin rosso, and in other countries is often sold as muscardin, qarnit tal-misk, bou msik or muzgavac. Like all coleoids, musky octopus is a high-quality and protein-rich food that contains plenty of Omega-3 fatty acids and iodine and has a taste reminiscent of veal. Usually only the eight tentacles are consumed, because the head is edible but frequently remains somewhat hard. Preparation of octopus requires a certain level of experience and above all patience, as the dish should not be leathery or tough and rubbery. Octopuses have fine muscle fibres that are embedded in their connective tissues and are positioned on top of each other in several layers. Raw connective tissue collagen is initially quite hard and requires the application of gentle heat for a long period to become soft and tender. If the heat is too strong, the muscle tissue contracts irreversibly and the octopus meat becomes unpleasantly tough. For this reason, octopus should not be cooked in boiling water, but instead simmered over a low heat. A simple rule of thumb for a perfect culinary result is to gently cook the octopus at 90-95°C, with one hour of cooking time per kilogram. Alternatively, it can be slowly stewed on a medium heat in the oven.
Most musky octopus are consumed fresh immediately after they are caught in the restaurants and home kitchens in the regions around where they are caught. This is not just true for the many tourist areas along the coast of the Mediterranean. The number of dishes, preparation variants and recipes that octopus is used for is just as large. It is consumed as spaghetti alla chitarra, polpo alla Luciana or ‘Greek style’, baked in olive oil, marinated or stewed as ragout, sliced into carpaccio or used as an ingredient in paella and seafood salad. The shelf life of fresh musky octopus is comparable to many fish. For whole musky octopuses that are constantly stored in melting ice after being caught, they will be good for 10 days. After that, their culinary qualities will have decreased so much that consumption would no longer be advisable. The decline in quality results mainly from autolytic reactions that destroy the protein of the animals and thus alter numerous biological and physical features. The microbial decay flora that arises is dominated by Pseudomonas species.
However, industrially produced or handcrafted octopus products have recently been developed that offer a high level of finishing and convenience, combined with a longer shelf life. These mostly include deep-frozen products or preserved products, for which there are many variants. Preserves made from tentacles cut into pieces in sunflower or, even better, olive oil, are particularly popular. These often include various additions such as paprika, garlic, chilli, or onion.