User:Paecilaema/sandbox

This template is a sandbox = Behavior (diet and reproduction) = This section will remain with the current information found in the Opiliones wiki page

= Anti-predator defenses = Some mammals, amphibians and other arachnids like spiders  and scorpions, have been found to predate on harvestmen. Opiliones display a variety of primary and secondary defenses or mechanisms that include morphological such as body armour, behavioral to chemical. Some of these defenses have been attributed and restricted to specific groups of harvestmen.

Primary Defenses
These are defenses are pre-predator encounter mostly to avoid encountering a potential predator, such as crypsis, aposematism and mimicry.

Crypsis
Particular patterns or color markings in their body reduce detection by predators. This causes an interruption of the leg outline, which can cause a recognition loss of the leg proportions as well as darker colorations and patters that work as a camouflage when they remain motionless. Within this Leiobunum genus there are multiple species with cryptic colorations that change throughout their life stages and their microhabitat shifts to match the new colorations. Many species, have also been able to camouflage their bodies by covering with secretions and debris from the leaf-litter found in their environment. Some hard-bodied harvestmen have epizoic cyanobacteria and liverworts growing on their bodies that suggests potential benefits for camouflage against diurnal predators.

Aposematism and Mimicry
There are harvestmen with elaborate and brightly colored patterns or appendages, that contrast with the body and could play an aposematic role possibly to avoid being attacked by potential predators. This also seems to correlate with their diel habits.

Additional to aposematism, some harvestmen may exhibit mimicry to resemble other species appearance to increase predator evasion. It is suggested that among Gonyleptidae, there are individuals from Uruguay that produce translucid secretions and have orange markings on their carapace that could be playing an aposematic role by mimicking the coloration of glandular emissions of two other quinone-producing species. Mimicry (Mullerian mimicry) occurring between Brazilian harvestmen that resembles others could be explained by convergent evolution. However, this last suggestion remains to be studied more.

Secondary Defenses
Secondary defenses allow for harvestmen to escape and survive from a predator after direct or indirect contact, and include: thanatosis, freezing, bobbing, autotomy, fleeing, stridulation, retaliation and chemical secretions.

Thanatosis
When responding to an attack, some animals simulate an apparent death to avoid either detection or further attack. Arachnids such as spiders practice this mechanism when threatened or even to avoid being eaten by females spiders after mating. It is also commonly observed within Dyspnoi and Laniatores suborders. Many species of these harvestmen often become rigid with legs either retracted or stretched, simulating death. This has been suggested that it operates as a second line of defense when detected by a potential predator in Hoplobunus mexicanus (Stygnopsidae).

Freezing
Freezing is the complete halt and immobility when they presence a threat. This has been documented in the Sclerosomatidae family. It has an increased immediate survival, however it coveys as cost on their foraging behavior by reducing their food and water intake.

Bobbing
To deflect attacks and enhance escape long-legged species, commonly known as daddy long-legs from the Eupnoi suborder, use two types of mechanisms. One is bobbing, for which these particular individuals tremble their bodies and it is suggested that it potentially serves as confusion and deflection of the exact identification and location of their body. This can be a deceiving mechanism to avoid predation from birds and other potential predators when enhanced by an aggregation of individuals all trembling together and suddenly dispersing away from the disturbance. This behavior is also seen by the cellar spider (Pholcidae) when their web is disturbed or during courtship, who are commonly mistaken by daddy long-legs (Opiliones).

Autotomy
Autotomy is a common strategy applied by many animals, for which they voluntarily amputate an appendage to enhance escape and survival when restrained by a predator. Eupnoi individuals, more specifically Sclerosomatid harvestmen commonly use this strategy to escape as a response to being captured. This strategy can be costly because harvestmen do not regenerate their legs. The loss of a leg reduces locomotion, speed, climbing ability, sensory perception, food detection, territoriality  and reproductive success. Overall, individuals with 5 or less legs are slower than individuals with all their legs and that the absence of a single leg can have an effect on their mobility and agility.

Autotomized legs provide a further defense from predators because they can twitch anywhere from 60 seconds to an hour after detachment. This can also potentially serve as deflection from an attack and deceive a predator from attacking the animal. It has been shown to be successful against ants and spiders.

Fleeing
Individuals that are able to detect potential threats, flee rapidly from the attack. This is seen by multiple long-legged species in the Leiobunum clade who either drop and run or drop and remain motionless. This is also seen when disturbing an aggregation of multiple individuals where they all scatter.

Stridulation
Multiple species within the Laniatores and Dyspnoi possess stridulating organs. Many arthropods such as beetles and spiders (Lycosidae) use it as intraspecific communication and has also been shown to be used as a second line of defense when restrained by a predator. More currently, researchers are trying to determine where is the stridulation originated from and if it varies among individuals.

Retaliation
Laniatores are mostly known for having many representative armored harvestmen species. When under attack, will often use their modified morphology as weapons. Many have spines on their pedipalps, on their back legs, or on their body. By pinching with their chelicerae and pedipalps they can induce harm to a potential predator. Also it has proven to increase survival against recluse spiders by injuring them and allowing the harvestman to escape from predation.

Chemical
Harvestmen are well known for being chemically protected and it is the most studied defense mechanism. They exude strongly-odored secretions, from their scent glands called ozopores. These secretions contain multiple volatile compounds that could potentially vary among individuals and be restricted within clades. Multiple studies prove that the chemical secretions act as a shield against predators and is the most effective defense they use by having a strong and unpleasant taste. These secretions have successfully protected the harvestmen against wandering spiders (Ctenidae), wolf spiders (Lycosidae) and Formica exsectoides ants. However, these chemical irritants are not able to prevent four species of harvestmen being predated by the black scorpion Bothriurus bonariensis(Bothriuridae).

Paecilaema (talk) 04:51, 3 March 2018 (UTC)