Atlas of Invertebrate Feed Species: Distinguishing Friend from Foe
American Association of Zoo Veterinarians Conference 2017
Eileen Henderson, DVM, MS; Dalen Agnew, DVM, PhD, DACVP
Diagnostic Center for Population and Animal Health, Michigan State University, Lansing, MI, USA


Parasites are a common finding in zoological collections.2 It can be difficult to distinguish between typical food species and parasites in captive animals, because amphibians, reptiles, birds, and fish are fed various species of worms and insects (e.g., earthworms, fruit flies, crickets). The objective of this study is to create an atlas by which normal food species and parasites can be distinguished. Commonly used invertebrate food items from the diets of captive reptilian, amphibian, avian, and aquatic species were collected from three zoological facilities, fixed in 10% formalin, and processed routinely for histology. Microscopic sections of common invertebrate food items were examined to identify specific characteristics of each organism. Organization of musculature, cuticle composition, and appendages are among the features that can be used to distinguish between parasites and common invertebrate food species.1 For example, earthworms have two layers of musculature (circular and longitudinal), which distinguish them from many parasitic nematode species. The features identified during this study can be used to evaluate the gastrointestinal contents of captive and wild reptiles, amphibians, fish, and birds submitted for necropsy.


The authors would like to thank the Potter Park Zoo, Detroit Zoo, and John G. Shedd Aquarium for donating invertebrate specimens for comparison.

Literature Cited

1.  Gardiner CH, Poynton SL. An Atlas of Metazoan Parasites in Animal Tissues. Washington, DC: Armed Forces Institute of Pathology; 1999.

2.  Panayotova-Pencheva MS. Parasites in captive animals: a review of studies in some European zoos. Der Zoologische Garten. 2013;82(1):60–71.


Speaker Information
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Eileen Henderson, DVM, MS
Diagnostic Center for Population and Animal Health
Michigan State University
Lansing, MI, USA

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