It can reach a maximum length of 250cm and a weight of 540kg. In adults the 'sword' reaches about a third of the total length. Females grow faster and a length of 100cm and 4 kg weight is reached within a year. At this size, scales and teeth disappear. After 5 years females measure 180cm in length and 100kg in weight.

Spawning in the Mediterranean occurs during the months June, July and August. A water temperature of 23°C / 24°C is necessary for successful spawning.

Dolphin Fish grows from a few grams to 2kg in a few weeks. It can grow up to 210cm in length and reach a maximum weight of 40kg at an age of 5 years. It spawns in temperate waters, during the months of June and July in the Mediterranean.

It migrates over immense expanses of ocean waters entering and leaving through the Strait of Gibraltar. This pelagic fish swims at high speed in large schools and rests under floating objects. Large specimen of these species are sometimes caught on tuna/swordfish longlines during the months of April - July.

It is built for sustained speed. Tuna may reach a length of 300cm and a weight of up to 650kg.

The eastern Atlantic population spawns in June in the western Mediterranean and in the Atlantic off the Strait of Gibraltar. During migrations of the eastern Atlantic population some exchange with the western population occurs. The latter spawns in the Gulf of Mexico. The females produce up to 10 million eggs, depending on their size. After spawning the weak adults undertake extensive migrations in search of food, mainly off Norway and Scotland, in the North Sea and Kattegat and occasionally in the Baltic Sea. The largest fish migrate the longest distances but avoid temperatures below 10°C.

The octopus has abandoned the mid-water in favour of a secondary bottom dwelling mode of life. They are generally rather slow moving and often sedentary although they can swim by jet propulsion. They mostly clamber around over the rocks using eight greatly elongated arms, which have two rows of well-developed suckers. They are territorial and they live in dens in which they hide and pounce on passing crustaceans or fish. When threatened it can discharge large quantities of dye containing melanin, a black pigment. This is released from an ink sac forming a cload to confuse predators.

Fertilisation is internal with a pre spawning time of 50 days. The female lays approximately 250,000 eggs. Incubation takes one month during which the female protects the eggs whilst making sure that there is adequate water circulation. Hatching takes place over a period of three weeks.