Most large squid grip prey with suckers reinforced by rings of chitinous teeth. Mesonychoteuthis adds hooks. Its tentacle clubs carry two rows of hooks, and the arms bear hooks that can swivel, allowing purchase from varied angles. The scars they leave on sperm whales are distinguishable from the circular ring marks a giant squid makes.
Size is the more commonly discussed feature. The best-documented specimen, landed by a New Zealand vessel in 2007 and now held at the Museum of New Zealand Te Papa Tongarewa, weighed roughly 495 kilograms, making it the heaviest cephalopod ever weighed. Mantle length rather than tentacle length is the meaningful measure here, and colossal squid have shorter tentacles than giant squid despite greater mass.
A persistent misreport treats colossal and giant squid as the same animal. They are separate species in different families, and the colossal squid is essentially confined to the Southern Ocean. Much of what is inferred about its diet and growth comes indirectly from beaks recovered in sperm whale and sleeper shark stomachs.