Sarah Griffin

Ecologist's Guide to Parasites

For BIO 361: Biodiversity of Parasites

An introduction to parasite diversity through a focus on thirty species

Parasite: a eukaryotic organism that lives on or in a host, benefitting at its expense

Phylogenetic Tree

Click the image below to be taken to an interactive phylogenetic tree, and click the number corresponding to the parasite species to be taken to its page:

*omitted: Myrmeconema neotropicum (phylum Nematoda) and Chondronema passali (also phylum Nematoda), which have not yet been added to the NCBI taxonomy database

Click links below to be introduced to a number of parasites in the following kingdoms:

PROTISTA

PLANTAE

ANIMALIA

FUNGI

Parasites by Life Cycle

Parasites can have direct (monoxenous) or indirect (heteroxenous) life cycles. Direct life cycles involve parasites that infect a single, definitive host species, and these can take parasitoid, castrator, or directly transmitted parasitic strategies. In indirect life cycles, parasites can have multiple hosts (for example, one or more intermediate hosts followed by the definitive host in/on which sexual reproduction takes place), and strategies include trophic or vector transmission. Additionally, a paratenic host may be involved in an indirect life cycle in which the parasite only uses the paratenic host for transport, not life stage completion. Micropredators feed on multiple hosts without killing them.

Below, parasites are organized in terms of life cycles and parasitic strategies

DIRECT LIFE CYCLE PARASITES

Parasitoid (kills the host)

Massospora cicadina

Castrators (render host incapable of reproduction)

Directly Transmitted Parasites

Trichomonas gallinae
Rafflesia arnoldii
Myrmeconema neotropicum
Cymothoa exigua (fish are currently this species' only known/studied host, though the life cycle is understudied)
Pseudodiplorchis americanus
Mermis nigrescens
Ophiocordyceps unilateralis
Cryphonectria parasitica
Pseudogymnoascus destructans
Chondronema passali
Pinnotheres pisum
Hemileia vastatrix

Divergent Single-Host Strategies

Naegleria fowleri (one host, facultative parasite)
Perkinsus marinus (one host, facultative parasite)
Phoradendron leucarpum (hemiparasitic plant)

An example of a direct life cycle.

http://www.aquaticparasites.org/background.html

Direct life cycles may involve free-living stages or direct transmission of infectious stages through contact between hosts.

https://link.springer.com/chapter/10.1007/978-3-319-99194-8_9

INDIRECT LIFE CYCLES

Trophically Transmitted

Two-Host

Toxoplasma gondii
Leucochloridium paradoxum
Spinochordodes tellinii
Myxobolus cerebralis
Dracunculus medinensis (2-host, plus fish as potential paratenic hosts)

Three-Host

Vector-Transmitted

Above: a trophically transmitted parasite's life cycle.

https://www.researchgate.net/figure/Indirect-life-cycle-where-the-fish-is-an-intermediate-host-The-nematode-eggs-larvae-a_fig3_251325739

Above: A vector-transmitted life cycle.

https://www.sciencedirect.com/science/article/pii/B9780128140437000042

MICROPREDATORS

Petromyzon marinus (ectoparasite that typically feeds on one host before detaching to breed elsewhere)

HEMIPARASITIC PLANTS WITH MULTIPLE HOSTS

Neottia nidus-avis
Nuytsia floribunda (hemiparasitic plant that parasitizes many hosts simultaneously)

Image Sources

Page Header

https://www.news-medical.net/news/20200519/Do-parasites-protect-against-SARS-CoV-2.aspx

Protista

https://www.sciencenews.org/article/malaria-parasites-may-have-their-own-circadian-rhythms

Fungi

https://ecologyfieldnotes.com/2017/02/06/the-walking-undead-zombie-ants-and-the-strange-effects-of-parasitic-fungi-on-ant-behaviour%E2%80%8B/

Plantae https://commons.wikimedia.org/wiki/File:Rafflesia_arnoldii_Bengkulu_02.jpg

Animalia https://www.acsh.org/news/2016/08/04/parasitism-evolved-at-least-223-times-among-animals

References

Poulin R. (2011). The many roads to parasitism: a tale of convergence. Advances in parasitology, 74, 1–40. https://doi.org/10.1016/B978-0-12-385897-9.00001-X