Atlantic white-sided dolphin

Lagenorhynchus acutus

2 - 2.8m

Yellow and grey


Dorsal fin

Atlantic white-sided dolphins are robust and have an abnormally thick tailstock. They have a distinct colour pattern; a dark back and dorsal fin, grey sides and white underbelly. They also have a thin white stripe along their flank, which goes to a yellow-tan colour on the tail stock. They have a slopping head and a tall curved dorsal fin.

Key features: 

  • Slender head and short beak 
  • Tall, dark, falcate dorsal fin 
  • Distinctive yellow, grey and white patterned flanks 
  • Highly energetic and acrobatic 


The Atlantic white-sided dolphin is a fast swimmer revealing only their upper back as they pass through the water. They are also known for their acrobatics, often exhibiting exuberant breaching and tail-slapping displays. They are sociable dolphins that like to hang out with large whales, riding in their bow waves. The are found in groups of 1-15 individuals, but huge aggregations occur in deep offshore waters. 



The range of the Atlantic white-sided dolphin is similar to the white-beaked dolphin; it’s confined to the cool temperate and sub-arctic waters of the North Atlantic especially over the continental shelf and slope.

Study whales and dolphins as an ORCA OceanWatcher

The ORCA OceanWatchers online training course, along with a bespoke app, will enable everyone to collect data about whales, dolphins and porpoises. And it can be collected from anywhere that you can see the sea - whether that’s from your local beach, on holiday at the coast, scanning the seas from a cruise ship, travelling via ferry, or from your own boat.

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