Rare Pelagic Tunicate - Helicosalpa virgula

[Davide DB]

On December 30, I took the last dive of the year and ended 2023 on a high note by filming this very special creature swimming under the boat in 10 meters of water. I'm in Tuscany, Italy, in the Mediterranean sea.

Initially I had misidentified it by mistaking it for a Siphonophore but then, thanks to the report of a biologist I found out that it is a very rare salp. Helicosalpa virgula.

Species within the genus Helicosalpa are pelagic tunicates with keg-shaped solitary zooids and aggregate zooids in chains (not whorls). They are also among the most rarely collected salps, with most observations from subtropic and tropic regions. Pictures and videos of live, aggregate helicosalp species in situ is rare.

 

https://www.researchgate.net/publication/341934517_Encounters_with_the_rare_genus_Helicosalpa_Chordata_Thaliacea_Salpida_using_citizen_science_data

 

Sea temperatures are rising. 2023 was terrible for us, and 2024 does not bode well. The temperature at the bottom is 14 degrees Celsius, which is normal for these places, but in the first few meters we still have a small thermocline of a couple of degrees. As a result, the surface water is murky because of sediment brought in by streams and rains, and there is very good visibility at the bottom, typical of the summer months. However, even in not the best visibility, it was worth filming this alien 😄

 

 

 

[Davide DB]

I discovered later that a Norwegian biologist is conducting a citizen science campaign on these critters.

 

[Chris Ross]

Nice job Davide, always fun to find something rare and even better get great footage of it.