How The Species Proteus Anguinus Are Adapted To The Extreme Environment: Caves
Chemical communication is acknowledged to be of immense significance in animals especially in cave dwelling species such as Proteus angunius which are blind and therefore unable to use vision to regulate their behaviour. A study was carried out to investigate the significance of chemical communication in the social behaviour of the stygobitic salamander Proteus angunius and the facultative cave inhabitant Euproctus asper. It was found that in relation to social interaction between members of the species Proteus angunius non-sexually active members displayed an attachment to a dwelling spot, and marked it through the use of faecal pellets. These faecal pellets behaved as a guide, attracting conspecifics to reposition their dwelling spot and form steady open groups (Guillaume, O 2002).
It was shown that Proteus angunius could locate their own dwelling spot when it was dislodged. Yet, they favoured a dwelling spot of a conspecific or that had the faecal pellets of a conspecific over their own. When two salamanders were given the option between two control spots they shared the shelter, when given the option between their own dwelling spot or the others, they used each indiscriminately and regularly shared. This data would suggest Proteus angunius employ chemical signals as a medium for inhabiting shared shelters and for social behaviour (Guillaume, O 2000). In contrast the sexually active males of the species Proteus anguinus live separately. Through violent behaviour towards intruders excluding sexually active females, males are able to form territories to allow for procreation. Gregariousness is a common characteristic to both species. It is believed that attraction to conspecifics enlarges the odds of finding a mate and aids in the hunt for food (Guillaume, O 2002). The subterranean Proteus angunius exhibited successive periods of catabolism of lipids and proteins throughout food deprivation. The significant resistance to continuing fasting and the rapid revival from nutritional strain can be explained due to its aptitude in staying in an extended condition of protein sparing and provisional torpor. Proteus angunius had decreased metabolic rates which act as a crucial adaptation to life as a cave dwelling vertebrate where food sources are irregular and in short supply (Hervant, F et al,. 2001). Proteus angunius successively endured twelve hours in a state of anoxia at 12 degrees Celsius.
These conditions did not alter Proteus angunius oxidative condition although liver and muscle antioxidant enzyme activates diminished under eight hours of anoxia, and only revert back to elementary level throughout reoxygenation (Issartel, Julien 2009). An investigative examination of the morphology of the skull in Proteus angunius angunius (the white olm) and Proteus angunius parkelj (the black olm) was carried out. The Proteus angunius parkelj has a noticeably broader cranium, smaller vomers which are located further apart than that of the Proteus angunius angunius. It was found that the Proteus angunius angunius had a more extended skull along with an anteriorly positioned jaw articulation point; this can be deemed as an adaption for enhanced feeding success, and compensation for their absence of sight. Proteus angunius parkelj showed a reverse development of troglomorphic characteristics compared to that of Proteus angunius angunius (Ivanovic, Ana et al,. 2013).
A study between both Proteus angunius angunius and Proteus angunius parkelj was carried out to investigate the difference between the regressed eye of the Proteus angunius angunius and the average fully formed eye structure of Proteus angunius parkelji. In the retina of the Proteus angunius parkelji the primary rods, red receptive cones and a third photoreceptor, which could signify a blue or UV receptive cone were found. Photoreceptors in the regressed eye of the Proteus angunius angunius are comprised of deteriorated outer segments, containing a small number of whorled discs and irregular clusters of membrane. The existence of immunopositive optical pigments suggests the probability that the photoreceptors of Proteus angunius have preserved sensitivity to light (Kos, M 2001). It was shown that the eye and optic uses around five to seventeen percent of the entire energy consumption, which highlights that selection that reduces energy consumption can lead to eye loss. (2015)Living in perpetual darkness brings challenges for Proteus angunius such as environmental perception and orientation.
The olfactive epithelium of Proteus angunius was found to be unusually thick, compared to that of other vertebrates which share the same basic olfactive structure which is pseudo-stratified and composed of basal cells, sensory cells and supporting cells. Proteus angunius was also found to have a fourth cell type. Proteus’ have an extremely well established sense of smell; they could sense about one kilogram of prey in two hundred and fifty centimeters cubed of minimum current water. This low recognition level is most likely an adaptive measure for surviving in the subterranean environment (Dumas, P Chris, B 1998). The reduction or loss or body pigmentation is an adaptive measure employed by Proteus anguinus. The total absence of melanin pigmentation or albinism is regulated by loss-of-function mutations in the oca2 gene.
The reaction of Proteus anguinus and Euproctus asper to living and non-living chironomids in light and in darkness was tested. Prey positioned at a distance of thirty centimetres were detected and found by both species. Proteus anguinus reacted to non-living prey in light quicker and caught live prey in the dark more prompt than Euproctus asper (Uiblein, F 1992). Proteus anguinus is more morphologically suited and adapted to detecting and locating prey in the dark due to their lack of vision and pigmentation which has led to the enhancement of their other senses such as hearing and smell (Borowsky, R 2018).
