Encyclopedia of Parasitology

2016 Edition
| Editors: Heinz Mehlhorn

Orientation

Reference work entry
DOI: https://doi.org/10.1007/978-3-662-43978-4_2242

Many parasites which actively invade or attack their hosts perform an ambushing strategy of  host finding, i.e., they await their hosts in their selected microhabitats (e.g., many species of trematode  cercariae, infective nematode larvae, and  ticks). However, other parasites actively approach towards their hosts employing very different types of orientation. Aquatic invasive larvae such as some trematode miracidia and cercariae may reach their hosts by chemo-orientation along gradients of certain host-emitted compounds. In most species, the type of orientation is a chemokinesis (random, undirected changes of the path of swimming in response to an increase or decrease of the stimulus concentration); but chemotaxis (directed movements along the concentration gradient of the stimulus) has also been described ( Host Finding,  Miracidium,  Trematodes,  Cercariae). Terrestrial host-searching parasites such as certain nematode larvae and ticks may orientate along thermal gradients, odorous...

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© Springer-Verlag Berlin Heidelberg 2016