Microbial Life > Topics of Interest > Marine Symbiosis

Marine Symbiosis

Created by Sarah Bordenstein, Marine Biological Laboratory

What is Symbiosis?


The term symbiosis is used to describe any permanent or long-lasting association between two or more different species of organisms. In the cases presented below, the term host generally refers to the larger member of the partnership, while the smaller member is known as the symbiont, or symbiote. The host typically provides nourishment and shelter for its symbiont, while benefits to the host vary considerably in each type partnership. These relationships may be classified by the type of association, degree of intimacy, and level of dependence.

Classification of Symbiotic Relationships


Type of associations

Degree of intimacy

Dependence on the symbiosis


Marine Symbiosis


Symbiotic interactions involving microorganisms are essential to the ecology of the marine environment. The collections below illustrate the diversity, depth, and specificity of such relationships.


Pompeii Worm: The Pompeii worm is a deep-sea polychaete that resides in tubes near hydrothermal vents. It is able to survive extreme temperatures by forming a symbiotic relationship with the protective "fleece-like" bacteria on its back.




Squid - Vibrio: The Hawaiian bobtail squid, Euprymna scolopes, houses a colony of luminous Vibrio fischeri in its specialized light organ to serve as anti-predatory defense. The light produced by the symbiotic bacteria is emitted downward, and the squid can manipulate the intensity of the light to match the intensity of down-welling moon and starlight, thus masking its silhouette to evade bottom-dwelling predators.


QPX, Quahog Parasite Unknown




Additional Resources


For additional resources about Marine Sybmiosis, search the Microbial Life collection.