Rotifers of the Great Lakes

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Approximately 275 species of rotifers have been reported for the Great Lakes. This partial list includes most of the planktonic (free-living) species. Great Lakes rotifers, particularly the soft-bodied forms have not been well studied. No data is included for Lake Superior rotifers.

Recent work indicates that rotifers may be important in packaging smaller material (e.g., by eating bacteria and detritus) into a form that is useful to higher organisms (e.g., larger crustacean zooplankton and larval fish). All rotifers have a corona of cilia surrounding their mouth. These cilia move rapidly setting up a current which draws food towards the rotifer mouth. However, they can be selective feeders - filtering out particles of the wrong size and actively rejecting certain particles using cirri. Once food has entered the rotifer mouth, it is ground by the trophi, plate-like structures which serve as teeth. Most species are omnivores, feeding primarily on bacteria and algae, a few are predatory, feeding on smaller rotifers and protozoa.

Rotifers in the Class Monogonata are normally diploid females which reproduce asexually (parthenogenesis). When conditions become poor (e.g., no food, temperature, crowding), these females produce 'mictic' female offspring. Mictic females produce haploid eggs which become males (which are haploid) if unfertilized, or, if a male is available to fertilize the egg (making it diploid again) a resting egg (which can remain dormant until conditions become favorable). Males are smaller than females, in some cases they may resemble the female, but usually they are reduced to a swimming reproductive organ, in many cases little more than a sperm sac with a tuft of cilia. Males generally live only a few hours (to days) dying immediately after reproduction. Rotifers in the Class Digonata are entirely amictic females, they apparently do not produce mictic females, males, or dormant eggs. Instead, the entire rotifer adult can survive extreme conditions by transforming to a resting stage.

Class Monogonata - Order Ploima

Keratella sp.

Family Brachionidae

 

Class Monogonata - Order Flosculariacea

Floscularia conifera in plant

Family Flosculariidae

Conochilus hippocrepis

Family Conochilidae

Filinia longiseta

Family Testudinellidae*

Hexarthra mira - 1 of 4 similar pictures in this collection

Family Hexarthridae

* ITIS separates Testudinellidae into 3 separate families: Filinidae (including Filinia), Testudinellidae (including Testudinella and Pompholyx) and Trochosphaeidae (including Trochosphaera). Stemberger places them all in a single family, and other references variously split them into 2 families.

Class Monogonata - Order Collothecacea

Collotheca ornata

Family Collothecidae

 

Class Digonanta - Order Bdelloida

Philodina inopinata

Family Philodinidae

Based on:

Rotifer Links

Globe icon indicates link to a non-NOAA site.Rotifers by Wim van Egmund

Globe icon indicates link to a non-NOAA site.Rotifers of Cootes Paradise and Hamilton Harbour

Globe icon indicates link to a non-NOAA site.Rotifers and how to find them. by Roy Winsby

Globe icon indicates link to a non-NOAA site.Rotifer Collection Search - The Academy of Natural Sciences, Philadelphia

Globe icon indicates link to a non-NOAA site.The Homepage of Ruediger Rudolf - Cladocera, Rotifers and Protozoa

Globe icon indicates link to a non-NOAA site.Introduction to the Rotifera - Berkley

Globe icon indicates link to a non-NOAA site.Freshwater Rotifers: An Introduction - Micrographia

Globe icon indicates link to a non-NOAA site.Welcome to the Wonderfully Weird World of Rotifers

Globe icon indicates link to a non-NOAA site.Rotifers - Coastal and Marine Biodiversity

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