The Mutant Giant Squids left tar on the surface of Jamaican waters as a part of their digestive system, and Elsie Chapman and Mendel Craven were called to investigate them. They soon deduced that the tar was a form of external digestive system, but the Squids quickly coated them in their tar and dragged them under. They were soon rescued by the rest of H.E.A.T., and the Squids attacked them. H.E.A.T. rushed into the lower decks and were able to shut the door, but a Squid was able to tear it off. The largest one nearly caught Niko Tatopoulos, but was killed by Godzilla. Several Mutant Giant Squids retaliated by working together to drag Godzilla down. This did not have the desired effect due Godzilla's amphibious nature. After surfacing, Godzilla terminated the remaining Squids, which prompted their predator, Crustaceous Rex to the surface due to a limited food supply.
- The Mutant Giant Squids can spit tar that entraps prey and slowly digests them alive.
- The Mutant Giant Squids are adapted to live underwater.
- The Mutant Giant Squids have the strength to hold humans and bring small ships underwater.