Due to its abundance, predator-prey interactions, and economic importance as a major fishery resource, The Humboldt squid is an important species as a midlevel carnivore in the food web of the pelagic ocean ecosystem. The interactions that the Humboldt squid engages in everyday life are below!
D.gigas is considered a lifetime predator from its early paralarval stages continuing into adulthood, when the Humboldt exhibits extreme aggression in predation. Being a relatively social species, the Humboldt squid is often found in shoals as large as 1,200 individuals. These shoals surface at night to hunt various types of small fish , shrimp, krill, crustaceans, small squid, and other cephalopods. Dosidicus gigas has also been observed preying upon other D.gigas in the same shoal, a type of cannibalism that is very rare.
It is thought that a main reason for Humboldt squid undergoing diel vertical migrations to oxygen minimum layers in the mesopelagic zone during daytime is to avoid the grips of predators. Organisms that regularly hunt Dosidicus include: tuna, swordfish, sharks, larger fur seals, and especially sperm whales. Larger fish also consume juveniles, and paralarval Humboldts as well.
Many organisms serve as hosts to some type of parasite in their lives, and the Humboldt is no exception. While there are 9-12 parasitic worm species (trematodes, nematodes, and cestodes) that infect the larval Dosidicus gigas (Nigmatullin, et al., 2001), Chromidina elegans infects the juvenile and adult forms of Dosidicus. Chromidina elegans is a ciliate protozoan that lives inside the renal organs of cephalopods. The unofficial term "Endosymbiont" is used to describe the curious relationship between C.elegans and their host, because they seem to provide benefits to hosts in addition to causing damage by feeding off them. It is suggested that the movement of the cilia in Chromidina may assist in the flow of fluid through the renal organs, helping with effective urine removal (mapoflife.org).
D.gigas directly interacts with humans through commercial and recreational fisheries. Over the last few years D.gigas has supported the worlds largest cephalopod fishery with annual landings of nearly 800,000 metric tons (Gaston et al., 2010), and is now the 3rd largest fishery in Mexico (gillylab.edu).
With mantle lengths up to 2 meters long and weighing in at as much as 50 kilograms these notoriously aggressive squid are dangerous enough to pose a threat to humans in close contact. Dosidicus may attack divers when threatened and will continue to put up a fight even after they've been caught, blasting their captors with water and ink.
Some of the same species that prey upon the Humboldt squid are also preyed upon by fisherman in the eastern Pacific. Many recreational and commercial fisheries rely on the use of Dosidicus as an excellent bait to successfully catch many large fish, especially tuna and swordfish.
The appetite of the Humboldt squid puts them into competition with humans for a variety of commercially harvested fish, mollusks, and shrimp. With the recent shift in their range occurring, the Humboldt may begin to affect the fishery stock in the northern pacific leaving less available for the fisherman to harvest.