V originále
Invertebrates are a heterogeneous group and it is much easier to define common features of vertebrates than of invertebrates, which account for about 95% of all animals. It is a small body size that is characteristic of most of them. They typically have a short adult lifespan, suffer from limited thermoregulation and bear large energetic demands for long distance migrations. This hampers the extent of invertebrate travelling and only few invertebrates undertake migrations that compare with those of birds, sea turtles, or fish. It does not seem to be necessary or even possible for small invertebrates to have sensory circuits that allow them to precisely localize celestial orientation cues or to calculate geographical position. Hence, magnetoreception, which is the ability to perceive the magnetic field of the Earth (Geomagnetic field – GMF), would not seem to be vital for most invertebrates. However, findings that animals that do not migrate – for example, Drosophila, the cockroach Periplaneta americana and the nematode Caenorhabditis elegans – can orient themselves according to GMF make us reconsider our intuitive and possibly too anthropocentric views about the ways in which magnetoreception may be useful to animals and what its relative importance is within the hierarchy of other senses. Laboratory and molecular techniques well accessible on invertebrate models may provide answers to the basic questions of magnetoreception: how, where in the body, and why GMF is perceived by animals. The goal of this review is to show what recent discoveries have been made in research into invertebrate magnetoreception since my previous survey (Vácha, 2017) and what future research directions can be expected. My review deals with the difficulties of replicating experiments as well as with the ongoing widening of this field: from a magnetic compass perspective to other cases of general magnetic sensitivity sharing the following common component – the Cryptochrome molecule.