The animal kingdom is filled with countless wonders and surprises, one of which is a small, vibrant jumping spider species, Siler collingwoodi, that has developed not just one, but two strategies to avoid falling victim to predators.
This colorful creature, known as Siler collingwoodi, uses the trick of camouflaging with plants and adopting an ant’s gait to survive in the wild. It’s a fascinating display of adaptation, according to a study published in the journal iScience.
These spiders mimic ants in the way they move, a survival tactic that researchers have taken an interest in. Ants, unlike many other small creatures, are not a prey of choice for many predators. They have spiny defenses, sharp mandibles, and are unafraid to fight back.
Moreover, many of them are equipped with chemical repellents or venom that make them a less than ideal meal. The fact that Siler collingwoodi, the subject of this study, had already shown ant-like movement intrigued the researchers.
The researchers sought to understand just how convincing this mimicry was, whether the spider could mimic more than one ant species, and how effective this tactic was at warding off predators. In addition to movement, the spider’s brilliant coloration is a crucial part of its defense strategy.
“Unlike typical ant-mimicking spiders that mimic the brown or black body color of ants, S. collingwoodi has brilliant body coloration,” explained study first author Hua Zeng, an ecologist at Peking University.
At first glance, the spider’s bright colors seem to blend well with the surrounding plant life, but the researchers wanted to investigate whether this coloration actually served as camouflage against predators.
The researchers embarked on their investigation by gathering samples of wild ant-mimicking spiders from four geographic locations in southern Hainan, China.
To draw comparisons, they also collected another type of jumping spider that does not mimic ants, as well as five species of ants that were suspected models for the spiders’ mimicry.
Back in the lab, the researchers observed and compared how the ants and spiders moved. They scrutinized the use of individual limbs, their speed, acceleration, and whether the creatures moved in a straight path or followed a more complex route.
Interestingly, they discovered that Siler collingwoodi does not move like other jumping spiders. Instead, it mimics ants by raising its front legs to imitate an ant’s antennae, bobbing its abdomen, and lifting its legs in an ant-like manner. The spider’s gait closely resembled that of three smaller ant species, suggesting a preference for mimicking species similar in size.
“S. collingwoodi is not necessarily a perfect mimic, because its gait and trajectory showed high similarity with multiple ant species,” said Zeng. This trait of mimicking more than one ant species may actually benefit the spiders by allowing them to expand their range if the ant models occupy different habitats.
The team then subjected the spider’s defenses to two predators: a similarly sized jumping spider, Portia labiata, that preys on other spiders and has color vision, and a praying mantis, Gonypeta brunneri, a generalist predator with a monochromatic visual system.
To better understand the role of color camouflage, the experts modeled how the two predators would perceive Siler collingwoodi in contrast to other prey species against two plants that the spiders live on – the red-flowering West Indian jasmine (Ixora chinensis) and the Fukien tea tree (Carmona microphylla).
They found that the ant-mimicking spiders were better camouflaged from both spider and praying mantis predators on the jasmine plant than on the tea tree plant.
When given the choice between the ant-mimicking spider and the other jumping spider, the predatory spider showed a preference for the non-mimic. In 17 trials, the spider initiated five attacks, all of them directed towards the non-mimic. However, the praying mantises didn’t show any bias and launched attacks on both prey species equally.
“We initially thought that both predators would behave similarly in the antipredation experiments, but in fact, the simulated ant locomotion of Siler collingwoodi only worked for the jumping spider predator, while the praying mantis showed indiscriminate attacks on both ants and mimics,” noted study senior author Wei Zhang.
This difference in the behavior of predators could be attributed to the potential risk they face when attempting to eat an ant. Praying mantises are significantly larger than their prey and can safely consume spiny ants without risking serious injury. However, the same can’t be said for the predatory spiders.
“For the spider predator, a random attack on an ant could result in injury, so they are very careful predators and will only attack if they can distinguish Siler collingwoodi from ants with a high degree of certainty,” explained Zhang.
One intriguing discovery the researchers made was that any impairment to a limb negatively impacted the ant-mimicking spiders’ ability to avoid the predatory spider’s attention. It seems that an injury could hinder their ability to accurately mimic ants, making them more vulnerable to attacks.
In conclusion, the researchers found that the Siler collingwoodi’s dual strategy of colorful camouflage and ant mimicry effectively aids in its survival. However, while the mimicry seems to be particularly effective against spider predators, praying mantises appear undeterred.
This fascinating study sheds light on the complex adaptive strategies evolved by small creatures in their struggle for survival.
Mimicry, such as that of Siler collingwoodi, is a fascinating phenomenon in the animal kingdom, where one species evolves to resemble another, often for protection or some other form of advantage. This tactic can be used to deter predators, lure prey, or achieve other beneficial outcomes. There are several types of mimicry, including Batesian, Müllerian, and aggressive mimicry, among others.
Named after the English naturalist Henry Walter Bates, Batesian mimicry involves a harmless species evolving to imitate the warning signals of a harmful species to ward off predators. A classic example of this is the Viceroy butterfly (Limenitis archippus), which mimics the coloration of the poisonous Monarch butterfly (Danaus plexippus), thereby deterring predators that have learned to avoid the toxic Monarch.
This form of mimicry, named after the German naturalist Fritz Müller, involves two or more harmful species that share common predators evolving to resemble each other. This way, predators quickly learn to avoid all species with a specific warning signal. An example of this type of mimicry can be seen among several species of stinging wasps and bees, which share similar yellow and black banding patterns.
This is a form of mimicry where predators or parasites share similar signals with a harmless species, allowing them to avoid being correctly identified by their prey or hosts. The alligator snapping turtle (Macrochelys temminckii) is a good example of this. The turtle has a tongue that looks like a worm, and it opens its mouth and wiggles its tongue to lure in fish.
This happens within a single species, where some individuals mimic other individuals or parts of their body mimic other parts. For example, some snakes have tail markings that resemble their head, potentially confusing predators.
This is a rare form of mimicry where a deadly prey mimics a less harmful but lesson-teaching species. The idea is that a predator that survives an encounter with the less harmful species will avoid the deadly one.
These mimicry mechanisms, as seen with Siler collingwoodi, are a testament to the remarkable adaptability and survival strategies evolved by species over thousands of years. They highlight the intricate complexities of ecosystems and the delicate balance that exists within the animal kingdom.
Image Credit: Hua Zeng