Zooplankton of the Great Lakes
Brachionus
Site created by: Benjamin
Coyle |
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Classification:
Kingdom:
Animalia
Phylum: Rotifera
Class: Eurotatoria
(Sub Class: Monogononta)
Super order: Pseudotrocha
Order: Ploimida
Family: Brachionidae
Genus: Brachionus
Species: 24 child taxa (sub/forms) |
Distribution
and Habitat:
Brachionus species are highly plastic and can survive highly variable
environmental changes both seasonally and annually. Tolerant of cold,
salinity, changes in ionic composition and desiccation, species under the
genus Brachionus have a cosmopolitan distribution
as they have been found on all continents (Fontaneto
et. al, 2006; Alcantara-Rodriguez et.al, 2012). Species
of brachionous such as B. plicatilis (and
others) can be considered euryhaline and tolerate wide salinity
fluctuations by means of osmoregulation (Lowe et. al, 2005).
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Anatomy:
Brachionous spp
retain general rotifer body plans. Brachionous are
loricate, footed rotifers. At the posterior end of the body is an opening in
the lorica for a foot. This foot is divided, and
sometimes coiled. Some spp have a foot that is
completely retractile where others are not. Figure 1: Generalized Brachionous anatomy
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Species
Morphology:
Morphologies
of Brachionous spp are
highly contrasting. Species may have lorica with
distinct spines whereas some spines are no longer present. Within a single
species there can exist two different morphotypes
(Figure 2). B. plicatilis can be found in the small (s) morph or the
large (L). They differ in their lorica
length: 130 to 340 µm (average 239 µm) for the L-type and 100 to 210 µm
(average 160 µm) for the S-type. With these differences also come differences
in weight, shape of spines and optimal growth temperatures (L-type rotifers
have a wider temperature range while S-type rotifers have a higher
temperature resistance) (Morretti 1999).
Figure 2: Morphologies of Brachionous species. B. quadridentatus (A1 & A2) and B. calyciflorus anuraeiformis (B1 & B2) exhibiting variable posterior spine morphologies. (Photos via Plewka 2016) |
Life
history:
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Feeding
Ecology:
Brachionous spp
are filter feeders, ingesting bacteria, algae, yeast and protozoa. Studies
have found that some brachionous spp such as Brachionus quadridentatus and Brachionus plicatilis, tend to investigate their food and have the
ability to select particles on the basis of size. Using microplastics,
researchers were able to show that B. quadridentatus
actively selects for food 3 and 5 µm and B. plicatilis
selects for smaller particles (Heerkloß and Hlawa 1995).
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Works Cited:
Alcantara-Rodriguez JA., Ciros-Perez J., Ortega-Mayagoitia
E., Serrania-Soto CR., Piedra-Ibarra
E. 2012. Local adaptation in populations of a Brachionus
group plicatilis cryptic species inhabiting three
deep crater lakes in Central Mexico.
Freshwater Biology, 57:728–740.
Fontaneto D., De Smet
WH., Ricci C. 2006. Rotifers in saltwater environments, re-evaluation of an
inconspicuous taxon. Journal of Marine
Biology Association of the United Kingdom, 86:623–656.
Heerkloß, R., Hlawa,
S. 1995. Feeding biology of two brachionid
rotifers: Brachionus quadridentatus
and Brachionus plicatilis.
Hydrobiologia
313:219. Jersabek CD., Segers
H, Dingmann BJ. 2003. The Frank J. Myers Rotifera collection. The whole collection in digital
images. The Academy of Natural Sciences of Philadelphia, Special
Publications. Lowe CD., Kemp SJ., Montagnes DSJ. 2005. An interdisciplinary approach to
assess the functional diversity of free-living microscopic eukaryotes. Aquatic Microbial Ecology, 41,67–77 Morretti,
Alessandro. Manual on hatchery production of seabass and gilthead seabream.
Vol. 1. Food & Agriculture Org., 1999. Nogrady, T., Wallace RL., Snell TW. 1993. Guides to the
identification of the microinvertebrates of the continental
waters of the world. Vol. 4. The Hague: SPB Academic Publishing. Rotifera. Vol.l. Pp. 47-93 in
H.J.F. Dumont (ed.). Plewka, M. 2016 Rotifer Images. Digital
image. Pling Factory. N.p.,
n.d. Web. 24 Oct. 2016.
<http://www.plingfactory.de/Science/Atlas/KennkartenTiere/Rotifers/01RotEng/E-TL/Genus/Brachionus.html>. |
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