Salamander species have evolved a wide variety of defenses against predators. Larval salamanders possess chemical defenses like mucus membranes that deter consumption. They also rely on behaviors to avoid detection by predators. As adults, salamanders have physical defenses such as toxic skin secretions, protruding ribs, and the ability to detach their tails. Some species perform complex behaviors to evade predators, such as rolling down slopes to appear like debris. This diversity of antipredator mechanisms in salamanders has developed in response to selective pressures from predators throughout evolutionary time.

1. Tanner Knox
Rough Draft
Dr. Harmon
10/31/2019
Caudatan Antipredator Mechanisms
Animal species in ecosystems large and small all play a role in the food chain, taking the
place of predator, prey, or both. The nearly 600 species of salamanders within the clade
Caudata consist primarily of insectivorous and carnivorous animals, although they are also a
major prey species for larger predators. Salamanders are preyed upon throughout almost all
the stages of their lifetime. From aquatic larval form until maturity, salamander species are
constantly avoiding and thwarting consumption via predators. Many types of antipredator
mechanisms have evolved among these species, ranging from simple immobility to potent
tetrodotoxin found in the skin of the Rough-skinned newt (Taricha granulosa; Gall et al., 2011).
This wide array of defenses has evolved throughout time as a result of very specific and broad
selective pressures alike. This paper will describe many of the different defense types seen
among several salamander species and explain some of their evolutionary drivers.
Salamander Ecology
Salamander species across the globe vary greatly in size, habitat type, morphology,
defense, etc. Members of the clade Caudata are primarily found within forested or grassland
centered environments. Caudata is composed of ten different salamander families found

2. primarily in temperate regions throughout the northern hemisphere. Different species are
often characterized as partially aquatic, fully aquatic, or terrestrial depending on the reliability
of water for survival after maturity is reached (Kats et al., 1988). Most species lay eggs in some
form of water where larvae will undergo most of development/metamorphosis (Bruce, 1974).
Salamander species will prey on many different types of insects, arachnids, and earthworms.
They are also preyed upon by many different species as well. Various snakes, small/medium
sized rodents, fish, frogs, birds, etc. commonly prey on members of Caudata. The large amount
of diversity seen in species type alone also relates to the large diversity of specialized behaviors
and mechanisms seen providing protection against predators of different forms (Deban &
Marks, 2002).
Larval Defenses
In many species of salamanders, defense has adapted to start at the very beginning
stages of life. In the spotted salamander (Ambystoma maculatum), the larvae have a sulphated
acid mucopolysac- charide membrane around them helping to ward off predators. When these
membranes are experimentally removed and placed into varying groups with or without eggs
with membranes, predators will feed on those with no membrane. Although it is not
understood how this mechanism actually works, it is understood that it is present in order to
deter predator consumption (Ward & Sexton, 1981). This chemical defense is found in many
different species within Caudata promoting the survival of larvae by limiting palatability.
Essentially, predators will avoid consuming these larvae regardless of exhibited (larval)
behaviors.

3. Salamander larvae of any species are often preyed upon by a variety of predators, but
those developing in the presence of aggressive fish species in streams, creeks, and rivers find
themselves especially at risk. Even species such as the Giant Pacific Salamander (Dicampton
tenebrosus) are intensely consumed by cutthroat trout (Oncorhynchus clarki). Unlike the
sported salamander, these larvae are palatable to predators leaving them to rely solely on
behavioral predator avoidance mechanisms. Chemicals emitted by cutthroat trout can be
detected by the giant (pacific) salamander larvae providing cues to find refuge among rock beds
or obstruction. This behavior evasion, often triggered by chemical cues of some kind, is a
mechanism used by many different salamander species during the larval stage (Rundio & Olson,
2003).
Morphological/Physical Adaptations
Physical defenses have developed overtime in many different species of salamanders in
response to predatory pressures. A very common defense, also found in many types of lizards,
is tail autonomy. The nonlethal separation of the tail from the body can allow the salamander
to successfully escape predation as the predator is distracted by the false sensation of a
successful catch. In one study it was found that 17 of 25 individuals of Eurycea bislineata that
exhibited tail autonomy were successful in evading predation via garter snake (Ducey & Brodie,
1983). Noxious or toxic skin secretions have also become an important defense for species such
as the Rough-skinned newt (Taricha granulosa) and the Japanese fire belly newt (Cynops
pyrrhogaster). These secretions can simply make the animal taste vile or cause fatality if
consumed by predators (Brodie, 1977).

4. Some physical adaptations require the pairing of behavioral actions in order to help the
successfully thwart predatory attacks. In onse such species of Asian salamander, (Tylototriton
verrucosus), brightly colored and enlarged granular glands (poisonous) are displayed when the
species experiences a predator. Verrucosus is able to protrude its ribs in such a way that the
orange colored glands provide a warning to potential attackers. This posturing mechanism,
combined with physical adaptation, is used by several other species as well. In some species,
such as Echinotriton andersoni, the extreme protrusion of sharp ribs acts as a secondary
defense if the predator decides to continue with its consumption efforts, ignoring the
poisonous display of granular glands (Brodie et al., 1984).
Behavioral Defenses
Behaviors have similarly evolved in certain salamander species helping them avoid
predation. Simple behaviors such as running, immobility (detection avoidance), and
biting/fighting are common. Other more complex behaviors are also observed, including
posturing, rolling, and vocalization. This rolling and posturing behavior can be seen in the
Mount Lyell salamander (Hydromantes platycephalus), which will effectively coil its tail, tuck in
its limbs, and perform a rolling action in order to dodge predation attempts. Other individuals
of H. platycephalus were observed performing a coiled posture and then rolling among loose
rocks to appear as though they were falling debris. This coiled salamander would roll down the
slope for a distance, unfurl, and remain completely immobile to avoid potential predatory
detection while running (García-París & Deban, 1995).

5. Conclusion
The large diversity of salamander species has produced many spectacular forms of
predation defense from egg to maturity. Observing these behavioral and morphological
adaptations can assist in understanding coevolutionary relationships between predator and
prey as well as provide biologists with more phylogenetic evidence concerning the origins of
many different salamander species. Compiling information about the different modes of
predator defense can allow scientists to classify certain species in terms with their
environmental needs. It can be beneficial for conservationists to use this information while
developing management plans. Understanding the habitat requirements of species within
Caudata can often directly correlate with the type of defense they express.

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