Symbiosis and Parasitism

Vocabulary flashcards covering the terminology and concepts of marine symbiotic associations and parasitology based on Professor Alex Ford's lecture.

Symbiosis

A close, long-term association between two or more different species of organisms, which can be random, casual, facultative, or obligatory.

Symbionts

The organisms involved in a symbiotic relationship.

Mutualism

A form of symbiosis in which two species associate for their mutual benefit, represented by the interaction type ($+/+$).

Commensalism

An association whereby there is a clear example of benefit to one member while not harming the other, represented by the interaction type ($+/0$).

Inquilinism

A subdivision of commensalism in which one animal lives in the home of another, or in its digestive tract, without being parasitic.

Zooxanthellae

Algal symbionts classified as brown, yellow, or golden cells.

Zoochlorellae

Algal symbionts classified as green cells.

Cyanellae

Algal symbionts classified as blue-green cells.

Endozoites

Organisms involved in commensal associations that live inside other organisms.

Epizoites

Organisms involved in commensal associations that live on the surface of other organisms.

Parasitism

A close association where one organism, the parasite, depends on and derives benefit from another, the host, typically causing it some harm ($+/-$).

Prevalence

The proportion of infected hosts at a given time; calculated as the number of infected individuals divided by the total number of individuals.

Intensity

The number of parasite individuals of a particular species found in each infected host.

Mean Intensity

The total number of individuals of a particular parasite species in a sample divided by the number of infected individual hosts in that sample.

Abundance

The total number of individuals of a particular parasite species in a sample divided by the total number of individual hosts (both infected and uninfected) in the sample.

Definitive Host

The host in which the parasite reaches the adult stage.

Intermediate Host

A host that harbors the larval stages (e.g., $L1$ or $L2$) of a parasite in an indirect life cycle.

Paratenic Host

A host that serves as a temporary refuge for a larval parasite ($L2$) but is not required for the parasite's development.

Cercariae

The free-living larval stage of trematodes that emerges from the first intermediate host (molluscs).

Miracidium

The free-living stage of trematodes that hatches from the egg to infect the first intermediate host.

Acanthocephala

A group of thorny or spiny-headed worms characterized by a proboscis with hooks used to parasitize hosts like fish.

Externa

The external reproductive part of the parasite Sacculina that becomes visible on the abdomen of the host crab.

Feminization

A process where parasites, such as Microsporidia or Sacculina, convert genetic males into phenotypic females or cause males to resemble and function as females.

Vertical Transmission

The transmission of parasites from parent to offspring via the gamete, typically maternal due to gamete size differences.