Giant squid may be a bigger part of biomass than people think. I saw some estimates on sperm whale catches of giant squid and they may be eating thousands. There are far more of them than you might think, and they have a 3D living space. Sperm whale may be designed to hunt them.
Besides sperm whales, the other toothed whale species that are bigger than orcas (i.e. beaked whales) are also specialized in eating squid caught at great depths under water, though they eat smaller species than those preferred by sperm whales.
The ancestors of sperm whales were actually more like super sized orcas, which must have eaten vertebrates, either big fish or big marine mammals, but at some point in time some of them specialized into eating squid at great depths and only these survived until now, presumably because at some point there remained less available great vertebrate prey to sustain bigger predators than orcas and white sharks, so the bigger predators specialized in vertebrate prey disappeared both among whales and among sharks.
