4.2.5. Additional hypotheses
There were a few hypotheses mentioned in the literature that warranted
less attention based on their obvious lack of support or generality.
Koch (1978) proposed that extensive spiraling in scorpion burrows could
reduce the effects of wind-blown debris entering the burrow. This is
logical, but scorpions and other terrestrial animals often clear their
burrows of debris including blown sand, cave-in sand and vegetation
(Shorthouse and Marples, 1980). Spiral burrows produced by marine
organisms may help keep the burrow free of sediment debris. Another
hypothesis, raised for Gyrolithes , suggests that the helical
burrow promotes anchoring of the tracemaker in the burrow in a
high-energy environment (Gingras et al., 2008; see also Laing et al.,
2018). However, the Gyrolithes studied by Moosavizadeh and Knaust
(2021) reflected a low-energy environment. Finally, some male ghost
crabs (Ocypode ) may construct spiral burrows for courtship
(Schober & Christy, 1993; Clayton, 2005). However, only one species has
been shown to construct burrows with more than one spiral: at least some
of the burrows of Ocyopde ceratophthalmus exhibit two spirals
(Parenzan, 1931, in: Eshky, 1985; Fellows, 1966, in: Vannini, 1980).
Some authors have included the hypothesis that helical burrows serve(d)
as domiciles (domichnia) that protect the burrows inhabitants (e.g.,
Laing et al., 2018). We did not consider this hypothesis because it
cannot in itself explain the evolution, benefits, or function of helical
structure above and beyond what the aforementioned hypotheses (e.g.,
antipredator) attempt to explain.