Flexible Spatial Orientation and Navigational Strategies in Chambered Nautilus

Abstract

Nautilus is a remnant of an externally shelled cephalopod lineage that flourished between 450 and 60 million years ago. It is a deep‐water scavenger that lacks the complex brain and behavioural repertoire of its soft‐bodied relatives, the coleoid cephalopods. Nautilus makes repeated, nightly migrations from deep to shallow water along coral reef slopes to forage, thus an ability to navigate to known locations may be selectively advantageous. Alternatively, drifting passively with the current may be sufficient to locate food and mates distributed randomly over a large area. The derived neural structures that support learning and memory in coleoids are absent from the nautilus brain, indicating that substantial differences between learning abilities in nautilus and coleoids are likely. However, our previous work has demonstrated both associative and spatial learning in nautilus. In laboratory experiments, we tested whether Nautilus pompilius could learn to navigate towards a goal location using either visual cues or motor responses. Results indicate that animals relied both on proximate and distant visual cues to orient but did not use egocentric cues, a somewhat surprising finding given that nautilus spends most of its time in near darkness. Animals learned visual information rapidly and in some cases were able to switch to other tactics when salient visual cues were removed or manipulated.

The genetic structure of Nautilus pompilius populations surrounding Australia and the Philippines

“…Despite lacking the lensed eye and vertebrate‐like brain of other cephalopods (including dedicated lobes for learning and memory), N. pompilius has been shown to be capable of both spatial learning and navigational strategy (Crook et al . ; Crook & Basil ). Migration on a small scale is not completely unfeasible, but seems unlikely at the scale investigated in our study.…”

“…It has been hypothesized that this was in each case due to natal philopatry (Kassahn et al 2003;Buresch et al 2006). It has been speculated that this behaviour does not occur in nautiloids (Crook & Basil 2013), but gaps remain in our knowledge of N. pompilius ecology. Despite lacking the lensed eye and vertebrate-like brain of other cephalopods (including dedicated lobes for learning and memory), N. pompilius has been shown to be capable of both spatial learning and navigational strategy (Crook et al 2009;Crook & Basil 2013).…”

Guidelines for the Care and Welfare of Cephalopods in Research –A consensus based on an initiative by CephRes, FELASA and the Boyd Group

“…Nautiluses should have access to vertical space for movements and attachment at a variety of levels, thus meeting their natural habit of daily vertical migrations. 176,177 However, not too many vertical attachments should be added, as nautiluses naturally swim up and down whilst circling around the perimeter of tanks and require space to do so. Adding texture (artificial coral reef) to at least one wall of the tank may make it more attractive to the animal (and may promote egg laying; G. Barord, pers.…”

“…98,100,130,183–186 Rest/sleep-like–activity cycles are documented in S. officinalis , 102 O. vulgaris 101 and Octopus macropus ; 103 nocturnal vertical migration is known to occur in N. pompilius . 29,177 Changes could be an indication that ‘something is wrong’. d) Use of arms and tentacles . The behavioural repertoire of arm movements in cephalopod species is reviewed and described in Borrelli et al.…”

Response and place learning in crayfish spatial behavior

“…Tactile cues would presumably be available in the dark, but may not offer as much information or be as easily remembered as a single turn direction. However, another nocturnal aquatic species, the chambered nautilus, displayed the opposite bias, orienting poorly when required to use egocentric information and much more accurately when visual cues were present (Crook & Basil, 2012). Clearly, additional species must be studied to gain a better understanding of the selective pressures that shape the salience of egocentric and allocentric cues.…”