What Is a Group of Squid Called? Fascinating Marine Facts

4 minutes read

When multiple squid are observed together in the ocean, scientists refer to that collection as a shoal, and less commonly as a squad. Both terms describe aggregations of squid swimming together in a coordinated way, but shoal is the formal ecological term used in marine biology.

Why Do Squid Form Shoals?

Squid shoaling is not random; it has important adaptive value. Grouping provides several survival benefits:

• Predator avoidance: A large cluster of individuals can confuse or deter predators. Predators may find it more difficult to single out and target one squid in a tightly packed group.
• Foraging efficiency: Some squid species hunt cooperatively or in close proximity, increasing their chances of capturing prey. Observations of large shoals of Humboldt squid (Dosidicus gigas) show feeding frenzies that appear highly coordinated.

Coordination and Communication Within a Shoal

Squid are capable of sophisticated communication that helps maintain shoal cohesion and coordinate group behavior. They achieve this through changes in skin coloration, body patterns, and in some species, bioluminescence:

• Chromatophores and visual displays: Squid skin contains pigment cells called chromatophores that expand and contract rapidly, creating dynamic patterns and flashes of color. These changes can serve multiple purposes — camouflage, predator warning, social signaling, and coordination within a shoal.
• Bioluminescent signaling: In deep water, species like Humboldt squid use bioluminescent organs (photophores) to illuminate their bodies. This “backlighting” enhances the visibility of skin pattern changes even in darkness, allowing individuals to communicate and coordinate action within a group.
• Complex signalling sequences: Research suggests that some squid use patterned light and dark changes in sequences that resemble rudimentary communication or coded messages.

The ability to change color and pattern is extremely fast and flexible, enabling squid to adapt their appearance in real time, whether communicating with conspecifics or blending into their environment.

How Shoaling Benefits Squid Beyond Protection

In addition to safety in numbers, shoaling has broader implications for squid biology and marine ecosystems:

• Social interactions: Shoaling facilitates mating and social dynamics. Some reef squid species form tight social groups where individuals interact frequently, a behavior distinct from solitary lifestyles seen in other cephalopods.
• Sensory coordination: Studies indicate squid rely on multiple sensory inputs — including vision, mechanosensory cues, and possibly polarized light detection — to maintain alignment and respond to threats rapidly while in groups.
• Ecological role: As both predators and prey, squid shoals influence food web dynamics. Large aggregations can impact prey populations, and because many larger animals (e.g., sharks, dolphins, sea birds) feed on squid, the presence of shoals affects predator foraging success and distribution.

Shoal vs. School: A Note on Terminology

In marine ecology, shoaling and schooling describe group movement patterns:

• Shoaling refers to any aggregation of individuals of the same species, not necessarily moving in perfect unison.
• Schooling is a more synchronized form of shoaling, where individuals swim in coordinated directions and formations.

Many squid shoals may exhibit schooling behavior under certain conditions, especially when highly coordinated movement is advantageous (e.g., during rapid escape responses or collective foraging).

A Closer Look at Notable Shoaling Species

Humboldt squid (also called jumbo squid) regularly form large shoals of hundreds to over a thousand individuals and demonstrate complex color signaling patterns that vary with social context.

Reef and bigfin reef squid show shoaling and social behaviors closer to coastal environments, with individuals often maintaining proximity to one another and coordinating movements even in shallower waters.

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References

National Geographic. “Squid Facts.” https://www.nationalgeographic.com/animals/invertebrates/facts/squids

Wikipedia. “Humboldt squid.” https://en.wikipedia.org/wiki/Humboldt_squid

Smithsonian Magazine. “Humboldt Squid Glow to Communicate in the Dark.” https://www.smithsonianmag.com/science-nature/humboldt-squid-glow-communicate-dark-180974576

EcoWatch. “Squid Communication.” https://www.ecowatch.com/squid-communication-2645581892.html

National Geographic. “Camouflaged communication: the secret signals of squid.” https://www.nationalgeographic.com/science/article/camouflaged-communication-the-secret-signals-of-squid

Wikipedia. “Bigfin reef squid.” https://en.wikipedia.org/wiki/Bigfin_reef_squid

Journal of Experimental Biology. “Multiple sensory modalities used by squid in shoal coordination.” https://journals.biologists.com/jeb/article/219/18/2870/15425/Multiple-sensory-modalities-used-by-squid-in

Nautilus. “The light magic of squid.” https://nautil.us/the-light-magic-of-squid-238169