The white Atlantic cadlina is found, dispersed in widely separated populations, on rocky bottoms from the low tide zone to depths of 800 m, ranging from the Arctic to the North Atlantic (Canadian Arctic Archipelago, Spitsbergen, Iceland, Greenland).

Along the North American coast its range reaches as far south as Massachusetts.

[1] Cadlina laevis has a flattened, white, semitransparent, oval mantle.

[5] Minimum recorded depth is 0 m.[5] Maximum recorded depth is 250 m.[5] This nudibranch preys on encrusting slime sponges, such as Halisarca dujardini or, in deeper waters, the sponge Dysidea fragilis.

fifty days, they give small slugs, forgoing the planktonic larval stage.