Invisible to the eye, but not to science: the pygmy sperm whale leaves its mark in the Mediterranean
Mar 30, 2026Revealed by traces of DNA suspended in water
A discovery from the European project LIFE-CONCEPTU MARIS, led by ISPRA
New technologies are revolutionizing marine biology; an unexpected discovery is reshaping our understanding of biodiversity in the Mediterranean Sea. The pygmy sperm whale, or Blainville’s dwarf sperm whale (Kogia breviceps), previously believed to be absent from these waters, has been identified thanks to the analysis of environmental DNA (eDNA)—the collection of genetic traces that organisms leave behind in their environment.
No direct sightings, no underwater footage: the presence of this elusive cetacean has emerged through genetic traces released into the marine environment and collected in simple water samples. This innovative technique opens new perspectives for studying and monitoring hard-to-observe species and confirms the potential of “molecular investigation” as a key tool for exploring still poorly known ecosystems and updating species distribution in the Mediterranean.
The surprising discovery was made by researchers from the University of Milano-Bicocca, in collaboration with ISPRA, the Stazione Zoologica Anton Dohrn, and the University of Valencia. They worked within the European project LIFE-CONCEPTU MARIS, led by ISPRA and recently concluded, whose goal was to monitor cetaceans and sea turtles in the Mediterranean using commercial ferries as platforms for data and sample collection.
Profile of an elusive cetacean
The pygmy sperm whale reaches about 3–3.5 meters in length, inhabits tropical and warm temperate seas, and feeds mainly on squid, which it locates using sophisticated biosonar. Extremely rare to observe in the open sea, it is likely more widespread than it appears: it simply spends most of its life far from the coast and out of human sight.
To detect it, researchers collected seawater samples from commercial ferries in transit. In total, 12 liters of water were collected at each of the 393 sampling points across the central-western Mediterranean.
The water, immediately filtered on board, allowed scientists to capture all suspended biological material containing DNA fragments. In the laboratory, using advanced sequencing techniques, the surprising discovery was made: pygmy sperm whale DNA was found in 10 different samples, corresponding to at least 5 independent presence events. These traces were distributed across a vast area stretching from the Tyrrhenian Sea to the Strait of Gibraltar.
