04.02.2025 – Blue raft

Today we were able to observe a school of Short-beaked common dolphins (Delphinus delphis). Everyone seemed to be doing what they enjoyed. Some were hunting, others seemed to be in resting mode, while some were curiously checking out who was on the boat. There were lots of small By-the-Wind-sailor (Velella velella) floating on the Atlantic. They look pretty.

The By-the-Wind-sailor is a fascinating marine creature. It belongs to the hydrozoan class. It lives on the surface of the water. They glide across the oceans using their upright sail, which is steered by the wind. By-the-Wind-sailor usually have a deep blue raft. This protects them from UV radiation and helps them to camouflage themselves in the open sea. These animals are not really jellyfish. They are colonies of specialised polyps with different tasks such as reproduction or feeding. They feed mainly on plankton, which they catch with their tentacle-like structures. By-the-Wind-sailor have cnidocytes, but are generally harmless to humans. By-the-Wind-sailor are closely related to the Portuguese man o’ war (Physalia physalis), but have a less painful stinging venom. Their unique locomotion system, characterised by the slanted sail, is a remarkable example of natural adaptation.

By Fatima Kutzschbach

Sightings of the day

Ribeira Brava

13:30 Common dolphins, By-the-Wind-sailor