In terms of communication, Gnasthenomus petersii has been compared to songbirds, bats, elephants, dolphins, whales, as well as humans. On this point, Chomsky (2012) believes that the ability to communicate cannot be conflated with the ability to think (an attribute of consciousness). According to him, thinking is an exclusive characteristic of Homo sapiens that started 60,000 years ago, and language is used to express this genetic endowment. We take the view that this apartheid cannot withstand the plethora of anatomical, neurophysiological, and behavioral data that have been used to show that humans are merely an evolutionary species variation (Everett 2016; Herculano-Houzel 2009; Ingle 1973; Schiller and Tehovnik 2015; Vanderwolf 2007), and like all extant animals they have qualities that have made them extremely adaptable (now comfortably occupying most of the planet save Antarctica), an adaptation that—if not checked—could bring about their end, due to accelerated resource depletions because of increased global temperatures and rising sea levels due to man-made CO2 production (Hansen and Lebedeff 1987). Hence, Homo sapiens like all other animals are constrained by evolution, even though they have been able to understand and manipulate the genetic code and create the atomic bomb.

Now onto the electric fish. Such fish have existed for 120 million years (Bell and Grant 1997), which means their electrical strategy has been highly adaptive. An electrical biphasic pulse (composed of an anodal spike followed by a cathodal spike, lasting ~ 400 μs) is emitted spontaneously at rates of 1-100 Hz at the electric discharge organ (located at the tail) of the electric fish (see Fig. 1; Engelmann et al. 2009; Bell et al. 1992b). The pulse produces an electric field between the tail and the head of the fish. If a worm (a conductor) distorts the electric field, current flow is enhanced at the body location of the object (von der Emde 1999, 2010); and if a plastic object (a non-conductor) distorts the electric field, current flow is interrupted at the body location of the object. The fish has electrical cutaneous sensors that can discriminate between these two conditions; electrical signals can also be used to discriminate between near and far objects as well as to assess 3D object shape, including cross-modal object recognition (Schumacher et al. 2015). Such discriminations allow the fishes to hunt at night in the fresh-water rivers of the West and Central African rainforests.

The electric organ discharge serves three functions (Fukutomi and Carlson 2020) as coordinated by the forebrain and cerebellum: (1) electrical communication with conspecifics, (2) electrical detection of others by noting changes in the self-generated electric field, and (3) electrical detection of others by noting the electric field emitted by others. The skin surface of an electric fish contains electrical receptors along with other receptors: visual (the eyes), tactile/vibratory and proprioceptive (at the skin and tendons), and gustatory (at the mouth/snout) (Amey-Özel et al. 2019). All the signals from these senses are integrated by the forebrain.

The electric organ discharge is mediated by a command nucleus located at the base of the medulla. The latency between the neural discharge of the command nucleus and the electric organ discharge is as short as 4 ms (Bell et al. 1983; von der Emde et al. 2000). Once a command is issued, an efference copy signal is relayed to the cerebellum, so that an animal does not confuse its own electrical pulse with that of an external electrical source (Fukutomi and Carlson 2020). The gains of the efference-copy signal are adjusted using a similar computation as evidenced in mammals: namely, simple spike rates are tuned by the presence and absence of complex spikes such that the presence of complex spikes decreases the simple-spike rate, whereas the absence of complex spikes increases the simple-spike rate (Bell, Grant et al. 1997). The events must occur within a restricted temporal window of 30 to 200 ms, so that the sensory input coincides with the complex-spike period.

The command nucleus is innervated by a forebrain nucleus, the precommand nucleus, which typically discharges after the command nucleus but before the electric organ is discharged (see Fig. 2; Bell et al. 1983; von der Emde et al. 2000). Another area that discharges before the onset of the electric organ discharge is the mesencephalic command association nucleus (Fig. 2, MCA). It is noteworthy that many of the synapses at the command nucleus are gap junctions (Elekes and Szabo 1985), which assures that the signals converging onto this nucleus can be incorporated with minimal delays to affect electric organ discharges. Indeed, the latency to evoke an electric organ discharge by electrical stimulation of the percommand nucleus is as short as 4 ms (von der Emde et al. 2000), which is the shortest latency observed between the discharge at the command nucleus and activation of the electric organ.

So, where is the consciousness of the electric fish harbored? All declarative conscious representations are stored outside of the cerebellum in mammals and birds and confined to the telencephalon (Tehovnik, Hasanbegović, Chen 2024). The precommand nucleus is well outside of the telencephalon of the electric fish (TEL, in Fig. 2). Consciousness is predicated on having a well-developed telencephalon and hippocampal formation for the storage of declarative information that can be recalled to facilitate behavioral responses. Given the rich behavioral repertoire of Gnasthenomus petersii [e.g., having 3D object capabilities for near (via electricity) and far objects (via vision); being able to discriminate between living and inanimate matters using capacitance; and being able to communicate electrically with conspecifics, Fukutomi and Carlson 2020; Schumacher et al. 2015; von der Emde 2000] it would be surprising if the experiences of this animal were not stored explicitly, given that this fish can live up to ten years. Where such experiences are contained in the brain of electric fishes is currently not known (but see Gómez et al. 2016 for some clues).

Figure 1: The electroreceptors, the central nervous system, and the electric discharge organ are illustrated for Gnasthenomus petersii. Obtained from Wikipedia in reference to ‘Peters’s elephantnose fish/von der Emde (1999)'.

Figure 2: (a) Sagittal section through the brain of Gnasthenomus petersii. The precommand nucleus (PCN) and the command nucleus (CN) are illustrated. Notice the large cerebellum (VAL/C1-3) and the smaller telencephalon (TEL). (b) Recordings were made from the precommand and command nuclei as command signals were generated at the nuclei before the onset of the electromotor discharge (To) at the electric discharge organ. From figure 1 of von der Emde (2000).