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Sida Crystallina Taxonomy Kingdom - Animalia Phylum - Arhtropoda Subphylum - Crustacea Class - Branchiopoda Order - Cladocera Family - Sididae Genus - Sida Species – crystallina O.F. Muller 1776 Sida crystalline has three subspecies: Sida crystallina crystalline, Sida crystallina ortiva, and Sida crystallina Americana (Korovchinsky, 1992). Anatomy Sida crystallina is a larger species of the Cladocerans. Females can reach up to 4.0 mm in length and males can reach up to 2.0 mm in length (Korovchinsky, 1992; Balcer et al. 1984). Like others in the Sididae family, S. crystalline have a bivalve, oblong carapace that covers 6 thoracic appendages, a large head without a headshield, and large moveable antenules (Korovchinsky, 1992; Balcer et al. 1984). Similar to other Clodocerans, the first pair of antennae (antennules) have 9 sensory papillae which are used for chemosensory purposes. The second pair of antennae (antennae) are used for swimming (Figure 1; Thorp & Covich 2001; Korovchinsky, 1992). These have setae (>14) arranged in a row on the dorsal branch of the 2^nd antennae (Figure 3; Balcer et al. 1984). Male’s express much larger antennules than females do. S. crystallina is identifiable from other members of the Sida genera by its dorsal antennae being 3 segmented (Figure 3; Pennak, 1978). Another distinguishable characteristic, present within the Sida genera, are their anchoring organs (maxillary gland), used to attach to substrate, that secrete a gelatinous glue (Thorp & Covich 2001). This is visible on the dorsal part of their body behind their blunt head (Figure 1). Distribution Sida crystallina is a plant-associated species found in the litoral part of lakes, reservoirs and rivers (Korovchinsky, 1992). They are a less abundant crustacean in the Laurentian Great Lakes that exhibit a patchy distribution pattern (Cerbin1 et al. 2003). Patches range from low densities to densities reaching 370-5000 organisms m^-3. They have been reported in Lake Superior, Lake Huron, Lake Ontario, and Lake Michigan. Diurnal distribution patterns are not prominent for S. crystallina like most Clodocerans. They are typically consistent with staying along the margin stand of vegetation. Adults are more often found swimming between plants while early instars are more distributed nearer the surface (Fairchild, 1982). Feeding Ecology Sida crystallina are sessile filter feeders (Cerbin1 et al. 2003). However, unlike most plant-associated species they primarily feed on phytoplankton (Fairchild, 1982). S. crystallina has a relatively fast metabolism rate and is comparably higher than other Clodocerans. A study done by Downing and Peters (1980) showed that filtering rates decreased while food concentration increased. An increase in respiration occurs when there is a high abundance of food. This is due most likely by the increased metabolic needs in order support the increased grooming of the filters on the thoracic appendages. Interestingly, this may lead the animal to starvation by not meeting the increased metabolism demands (Thorp & Covich 2001). Feeding for S. crystalline typically takes place during the night. However, they will feed during the day. Fairchild (1982) found that feeding densities increase by one-third at night which is consistent with most plant associated zooplankton. Reproduction Sida crystallina can reproduce sexually and asexually, which is dependent on environmental conditions. However, the primary mode of reproduction is parthenogenetically. The presence of a certain stimuli such as crowding, photoperiod, or food, is when they will switch to sexual reproduction. The reproductive cycle generally begins around March or April, depending on environmental cues. According to Green (1966) egg production seems to be high during the spring and fall months with a low during the summer months. In October the majority of females will transition into producing resting eggs, which will not hatch until the following spring (Green, 1966). This change affects the structure of the population in November and December. At this time the females grow to a large size due to few recruits in the autumn population.	Figure 1 Sida crystallina’s dorsal maxillary gland (A) and its second antennules (B). Figure 2. Post abdominal claw with setae (A). Figure 3. Ventral and dorsal ramus of second antennae with swimming hairs. Dorsal ramus showing 3 segments. Figure 4. Sida crystallina with rostrum (A).
Works Cited: Balcer, M.D., N.L. Korda, and S. I. Dodson. (1984) Zooplankton of the Great Lakes: A Guide to the Identification and Ecology of the Common Crustacean Species. Pp110. University of Wisconsin Pres. Madison, Wisconsin. Cerbin,. S., D. J. Balayla, and W. J. Van de Bund. (2003) Small-scale distribution and diel vertical migration of zooplankton in a shallow lake (Lake Naardermeer, the Netherlands). Hydrobiologia, 491: 111–117. Downing, J. A., and R. H. Peters. (1980) The Effect of Body Size and Food Concentration on the in Situ Filtering Rate of Sida crystallina. Limnology and Oceanography, 25: 883-895. Fairlchild, G. W. (1980) Movement and Microdistribution of Sida crystallina and Other Littoral Microcrustacea. Journal of Ecology, 62: 1341-1352. Green, J. (1966) Seasonal Variation in Egg Production by Cladocera. Journal of Animal Ecology, 35: 77-104. Korovchinsky, N. M. (1992) Guides to the Identification of Microinvertebrates of the Continental Waters of the World 3: Sididae & Holopediidae: (Crustacea: Daphniiformes), pp. 1-5. SPB Academic Publishing. the Hague, the Netherlands. Pennak, R. W. (1978) Fresh-Water Invertebrates of the United States, Second Edition, pp. 365.  John Willey and Sons, New York, New York. Thorp, J. H., and A. P. Covich. (2001) Ecology and Classification of North American Freshwater Invertebrates, pp. 850-872. Second Edition. Academic Press. San Diego, California.