Risso's Dolphin

Fascinating facts about the Risso's Dolphin

• Risso's dolphins can plunge to almost 600 m (2,000 ft), as deep as a 60-storey building, by emptying their lungs and spinning almost vertically, letting them chase squid that hide in the dark deep layer. This extreme dive lets them exploit a food niche. Their ability to dive repeatedly to these depths underpins their role as deep-water cephalopod predators.
• Risso's dolphin wears a map of battle scars: linear, white-less marks cover most of the body, especially the dorsal and lateral surfaces. These scars result from male-to-male fights and lack of repigmentation, turning each wound into a permanent display that signals fitness and deters further challenges. The scar-laden skin therefore acts as a visual badge in their competitive mating system.
• Risso's dolphins live in tightly knit pods of 10-50 individuals, yet they can swell into "super-pods" of several thousand, the largest recorded being about 4,000 animals in one group. Smaller, stable sub-groups within these gatherings tend to be age- or sex-specific, fostering long-term bonds.
• Since at least 2017, Risso's dolphins have been spotted off Norway's sub-arctic coast, reaching as far north as Bleik's Canyon near Andøya. Regular sightings there suggest the species is expanding its range northward, likely driven by warming waters, shifting prey distributions, or competition with other cetaceans.
• In the Philippines' Tañon Strait, Risso's dolphin sightings have plummeted: a 1999 baseline counted 81 marine-mammal observations over 434 km of transects, while the 2019 survey recorded only 15 sightings along 202.76 km. The drop mirrors a broader decline in cetacean numbers and group sizes, likely tied to intensified boat traffic, illegal fishing, and storm-driven survey limitations, highlighting the strait's deteriorating health for these predators.

Sources

Every fact above was checked against these pages, and kept only where one of them states it.

• Wikipedia
• Mongabay

At a glance

About the Risso's Dolphin

In the dark, mysterious depths of the ocean, the Risso's Dolphin glides with effortless elegance, its scarred and weathered body a testament to a life of curious exploration and social intrigue. As it moves through the waves, its dorsal fin slices the surface with a gentle whoosh, leaving behind a trail of rippling water that belies the complexity of its underwater world. With a reputation for intelligence and playfulness, this enigmatic creature navigates the ocean's twilight zones, its clicks and whistles echoing through the darkness like a haunting melody.

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