Some deep-sea animals grow far bigger than their shallow-water cousins
Giant squid, giant isopods and colossal squid all belong to groups whose shallow-water relatives stay small, yet in the deep ocean they grow to extraordinary size. Biologists call the pattern deep-sea gigantism, and proposed causes include the cold, near-freezing temperatures, higher pressure, scarce food favoring bigger, more efficient bodies, and fewer predators. No single explanation accounts for every case, and the pattern remains an active area of research.