Symbiosis and Parasitism Lecture Notes

Flashcards covering definitions, ecosystem statistics, and specific examples of symbiosis, mutualism, commensalism, and parasitism in marine environments.

Symbiosis

A close, long-term association between two or more different species of organisms.

Symbionts

The organisms involved in a symbiotic relationship.

Mutualism

A form of symbiosis in which two species associate for their mutual benefit.

Commensalism

An association whereby there is a clear example of benefit to one member whilst not harming the other.

Inquilinism

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

Commensal (individual)

In commensal and inquiline relationships, the partner gaining an advantage.

Host

In commensal and inquiline relationships, the partner that provides the home or advantage to the commensal without being harmed.

Competition interaction notation

$$(-/-)$$

Predation interaction notation

$$(+/-)$$

Mutualism interaction notation

$$(+/+)$$

Commensalism interaction notation

$$(+/0)$$

Parasitism interaction notation

$$(+/-)$$

Number of Higher Animal Taxa (Phyla) in Marine ecosystems

$$32$$

Number of Higher Animal Taxa (Classes) in Marine ecosystems

$$73$$

Number of Higher Animal Taxa (Phyla) in Terrestrial ecosystems

$$12$$

Number of Higher Animal Taxa (Classes) in Terrestrial ecosystems

$$25$$

Number of Higher Animal Taxa (Phyla) in Freshwater ecosystems

$$16$$

Number of Higher Animal Taxa (Classes) in Freshwater ecosystems

$$33$$

Zooxanthellae

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

Zoochlorellae

Algal symbionts characterized as green cells.

Cyanellae

Algal symbionts characterized as blue-green cells.

Cassiopeia sp.

A type of jellyfish that lies upside-down on the seabed exposing oral tentacles containing algae.

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.

Urechis caupo

An Echiurid Worm that creates a U-shaped burrow shared by fish, scale worms, crabs, and shrimp.

Clevelandia ios

A fish species that lives in the U-shaped burrow of Urechis caupo.

Hesporone adventor

A scale worm species that lives in the U-shaped burrow of Urechis caupo.

Scleroplax granulata

A Pinnotherid crab that lives in the U-shaped burrow of Urechis caupo.

Bataeus longidactylus

A long-fingered shrimp that lives in the U-shaped burrow of Urechis caupo.

Diademichthys lineatus

A species of Cling Fish mentioned as an example of commensalism.

Stegopontonia commensalis

A species mentioned as an example of convergent evolution in symbiotic associations.

Carapus sp.

Pearlfish that live inside Sea Cucumbers (Holothurians).

Physalia sp.

Portuguese man-of-war, which associates with the fish Nomeus gronovii.

Nomeus gronovii

A fish that lives among the tentacles of the Portuguese man-of-war (Physalia sp.).

Cryptocentrus lutheri

A Goby Fish that shares a burrow with the Blind Shrimp Alpheus djiboutensis.

Alpheus djiboutensis

A Blind Shrimp that shares a burrow with the Goby Fish Cryptocentrus lutheri.

Lybia tesselata

A crab that carries sea anemones in its front claws (chelopeds) for defense.

Parasitism (Rohde definition)

Close association of two organisms, in which one (the parasite) depends on the other (the host) deriving some benefit from it.

Parasite (Poulin definition)

An organism living in or on another organism, feeding on it, showing some degree of structural adaptation to it, and causing it some harm.

Prevalence

The proportion of infected hosts at a given time.

Prevalence calculation example

If 4 hosts are infected and 6 are uninfected, Prevalence = $0.4$ or $40\%$.

Intensity

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

Mean Intensity

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

Mean Intensity formula example

$$(5 + 4 + 4 + 3) / 4 = 4$$

Abundance

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

Abundance formula example

$$(0 + 0 + 5 + 4 + 0 + 0 + 4 + 3) / 8 = 2$$

Direct Life Cycle

A life cycle that involves only a definitive host and a larval stage without intermediate hosts.

Definitive Host

The host in which the parasite reaches the adult (mature) stage.

First Intermediate Host (L1)

The first host used by a parasite with an indirect life cycle during its larval development.

Cymothoa exigua

A Crustacean Isopod parasite that replaces the tongue of the Spotted Rose Snapper (Lutjanus guttatus).

Lutjanus guttatus

Commonly known as the Spotted Rose Snapper, host to Cymothoa exigua.

Miracidium

The free-living larval stage of a trematode that hatches from the egg and infects the first intermediate host.

Cercariae

The free-living larval stage of a trematode that is released from the first intermediate host (mollusc).

Metacercariae

The parasitic stage of a trematode found in the second intermediate host (invertebrate or vertebrate).

Trematode first intermediate host

Molluscs.

Pseudoterranova decipiens

A member of Ascaridida (Anisakidae) with a life cycle involving seals, fish, and crustaceans.

Chlonorchiasis

An infection from raw fish that can cause jaundice and liver enlargement.

Anisakiasis symptom

Sudden, severe pain resulting from raw fish infection.

Acanthocephala

Commonly known as thorny or spiny-headed worms.

Proboscis with hooks

The anterior attachment organ of an Acanthocephalan parasite.

Sacculina sp.

A genus of Rhizocephala that parasitizes crabs like Carcinus maenas.

Interna (Sacculina)

The root-like system within the host crab that causes extensive damage to the endocrine organs, CNS, and gonads.

Externa (Sacculina)

The reproductive part of the Sacculina parasite that remains outside the host crab's abdomen.

Feminization

The process where a parasite causes a male host to resemble and function as a female, often seen in crab hosts of Sacculina.

Microsporidia

Parasites of Amphipoda (e.g., Gammarus) that can feminize genetic males into phenotypic females.

Vertical transmission

The transmission of parasites from parent to offspring via the gamete (usually maternal).

Nosema granulosis

A microsporidian parasite that infects Gammarus duebeni.

Dictyocoela duebenum

An alternative name for Microsporidium spA, which causes male-to-female conversion.

Gammarus duebeni

An amphipod host frequently used to study feminizing microsporidian parasites.

Paratenic Host

An optional host in a parasite's life cycle where no development occurs, used as a 'bridge' to reach the definitive host.