Daphnia lumholtzi most notable characteristics are its pointed helmet and large spines. 2 features that make the D. lumholtzi difficult to feed on allowing it to prosper as an aquatic invasive species. It was first introduced in 1990 in Texas and can now be found throughout southeastern USA.
Philip W. Lienesch and Moshe Gophen of the University of Oklahoma’s department of Zoology and Biological Station, are interested if inland silverside (Menidia beryllina) are size-selective predators of D. lumholtzi. By placing 3 various sizes of inland silversides in tanks with various sizes of D. lumholtzi, Lienesch and Gophen were able to determine inland silverside’s feeding habits. Smaller inland silversides preferred smaller D. lumholtzi, while the larger fish ate the large D. lumholtzi. Next Lienesch and Moshe tested their results in Lake Texcoma, comparing D. lumholtzi to native Daphnia, results were similar to labratory experiment, suggesting that when zooplankton is scarce, D. lumholtzi could become a food source for juvenile silversides.
Lienesch, P.W., and M. Gopen. 2005. Size-selective predation by inland silversides on an exotic cladoceran, Daphnia lumholtzi. The Southwestern Naturalist 50, 158-165.