Prospekt Depths, Intresting facts

Photo 1. Photo of a four-lined snake, taken on Ilovik Island. The snake has made its way into a blackbir’s nest in an old native, prickly variety of lemon tree and has caught a young bird. Does the lack of food encourage terrestrial snakes to undertake short migratory “trips” across the sea or are other reasons involved? (Photo by Ervin Raguzin)


Recently, the Maritime Police informed us about certain snake species swimming across the relatively narrow sea passage (about 250 – 350 metres) that separates Ilovik Island and Sv. Petar Island. If true, then these swimming snakes have probably caused much consternation among the islan’s residents.


As far as we could tell from photos received of a snake in the marine area of Ilovik Island, the snake in question is a four-lined snake (Elaphe quatuorlineata quattuorlineata /Lacéde, 1789/), an indigenous species, previously known in the Cres-Lošinj archipelago and found on the islands of Ilovik and Sv. Petar (Photo 1).

Commenting on this event, our co-workers who specialise in herpetology pointed out that it is not uncommon for snakes to swim across short distances of sea separating parts of land. In fact, it happens fairly often.

One such event, which has practically become a legend today, occurred in the mid-1950s in the sea area of Kačjak peninsula. A four-lined snake, (called gužvina in the Crikvenica region) decided to swim the 200 metres of sea that separates Punta Kačjak Cape and the small harbour of Bršćanovica on the Crikvenica Riviera. When it swam into a group of bathers the panic was considerable, so much so that the locals still remember and talk about the snake as an extraordinary event.

However, only rarely and occasionally do terrestrial snakes use the sea to swim short distances between two parts of the mainland or between the mainland and nearby islands. On the other hand, venomous sea snakes (which do not live in the Adriatic Sea but rather in the tropical and sub-tropical coastal waters of the Indian and Pacific oceans) are perfectly adapted to life in an aquatic environment – the sea and in fresh waters connected to the sea. Unlike terrestrial snakes that have a cylindrical body shape, sea snakes have a flattened body which facilitates movement through the sea and aids in propulsion. Interestingly, sea snakes belong to the same kinship circle as the four-lined snake spotted near Crikvenica and in the Ilovik marine area. Namely, these snakes are members of a broader Aesculapian snake group.

As this brief report points out, it is not rare for snakes to swim in the Adriatic and it could happen that while bathing in the sea you might encounter a snake. Although we are not snake experts, we can base our recommendations on how to behave in such a situation on rules of conduct with other types of wild animals: Stay calm and do not panic. Do not approach the snake and do not touch it (because you can’t be sure that it isn’t a venomous snake that has decided to go swimming!). Slowly and calmly move away from the swimming snake.

It goes without saying that most of the encounters between people and snakes in the Adriatic, as the two cases described above testify, involve non-venomous and harmless snakes such as the four-lined snake which is (by the way) a strictly protected species.

Thematic units: sea, fauna

Key words: four-lined snake (gužvina), Elaphe quatuorlineata quattuorlineata, snakes in the Adriatic, marine area of Ilovik and Sv. Petar Islands, Crikvenica Riviera

M.R., I.J. i E.R.