A very sophisticated creature indeed!
The common cuttlefish is a migratory species and is one of the largest and best-known cuttlefish species. In the spring and summer months, it is time for the cuttlefish to spawn and they stay inshore for this purpose. They can be spotted in Gozo in reasonably shallow water. During the winter and autumn months, they migrate to depths of 100 to 200 meters. They grow to 4 kg in weight and have a mantle length of 49 cm. This is quite large for a cuttlefish, compared to its counterparts in subtropical countries. They are much smaller in size and weight, rarely exceeding 30 cm in mantle length.
European cuttlefish are native to the North Sea, Baltic Sea, and the Mediterranean Sea. There is a subspecies which lives around the coastal waters of South Africa. Cuttlefish live on the seabed, both muddy and sandy bottoms are tolerated as well as brackish water conditions. The modern-day species goes way back to the Miocene Epoche which was 21 million years ago.
The European cuttlefish have many predators including seals, dolphins, sharks, fish, and other cephalopods. To defend themselves from predators, they have some defensive mechanisms which include a siphon they can use to shoot water out of. The thrust of water from the siphon propels them away from danger quickly. Ink is used to distract and disorientate a predator while the cuttlefish swims away. They have a camouflage ability which can help them avoid predators and not be seen.
A study on prey habits:
In 2008 a study revealed that European cuttlefish embryos if exposed to a certain species of prey, such as crabs, will hunt primarily for this prey later in life. Although shrimp is preferred over crab, embryo cuttlefish exposed to crab switched preference and hunted crab more often than the shrimp.
In daylight hours the cuttlefish is inactive. They lay buried below the substrate and stay there until dusk. At night they actively search for prey and will ambush their prey directly from under the substrate. European cuttlefish are carnivorous and sometimes cannibals. Their diet consists of shrimp, crab, small fish, molluscs such as snails and clams. When prey is low and food is scarce they are known to eat other cuttlefish.
The cuttlefish including its mantle is the largest species of cuttlefish and this does not include their arms and head. Inside the mantle, the reproductive organs and digestive tract are found. The internal shell called the cuttlebone is also found there too. Two highly developed eyes and eight arms around the mouth are used to spot, hold and move prey around. Two tentacles quickly capture prey, and a radula is used to rip and tear the prey apart. Cuttlefish are well known for their unmatched camouflaging abilities. This clever ability is possible due to light scattering leucophores, pigmented chromatophore organs, and structurally reflecting iridophores. All of these special characteristics can be located in their skin.
This clever creature has the ability to change the texture appearance of its skin as well as its colour. This is all accomplished even though the cuttlefish is colour-blind. The ability to camouflage in this way is categorized into four main types, they are mottle, stipple, uniform, and disruptive. This is a very complex and complicated character and is found in both adult and juvenile cuttlefish alike. Juvenile cuttlefish learn from a young age the importance of camouflage and survival.
Between the age of 14 – 18 months cuttlefish reach sexual maturity. Male cuttlefish will display a black and white zebra pattern on their mantle to attract females. The females will display a uniform grey mantle indicating to the male she is ready to mate. The breeding season takes place during spring and summer in shallow waters. The number of fertilised eggs can be anywhere from 100 to 1000. Cuttlefish are internal fertilisers, so the female keeps her eggs in the oviduct for 30 to 90 days. Once she has fertilised them, she lays them in seaweed, shells, or other substrates. The choice of the site is important to prevent the eggs from drifting away. To help camouflage them against predators, they receive a coating of ink.
Sepia officinalis is fished in the Mediterranean, Greece and Spain. In some areas the population is very low, almost over-exploited, in others, the numbers are still stable.
The cuttlebones inside the mantle of the cuttlefish are used and sold to the pet bird industry. It is a form of calcium, keeps the bird’s beak trimmed as well as providing entertainment for a caged bird. Although I am sure, a bird would prefer to find its own entertainment outside in the wild and not in a cage!
Cephalopods ink is believed to have beneficial health effects including anti-inflammatory and anti-oxidant activity. Anti-cancer properties and anti-hypertensive possibilities are also being investigated. The food industry recognized it because it has a similar taste to octopus or squid and contains proteins and lipids. Cephalopod ink is used to paint and draw as well as being used in the cosmetic industry. The food industry uses ink to flavour and as a food dye.
Come and see more of these fascinating creatures with us at Dive Smart Gozo.