Twin-flagged Jumping Spider Mating Ritual

The twin-flagged jumping spider is a common “ant-hunting” species occurring in the southeast of North America and Mexico. The mating behavior of this spider is well-documented, featuring over 22 distinct display movements. These include various ways the spider waves its brightly colored pedipalps that earned the species its name.

Here in this footage, you will see the mating ritual of the twin-flagged jumping spider and the potential role of ants as prey in mediating male-female conflict. Ants offer an abundant resource, but they are also well-defended with their thick exoskeletons. They can bite, sting, and even spray formic acid, and are capable of recruiting nest mates for defense. However, the benefits of preying on ants must outweigh the risks. Although the twin-flagged jumping spider eats a wide variety of prey, it almost never passes up a chance to attack a nearby ant.

In this rendering, you can see the spider holding an ant prey by a specific body segment called the propodeum. The term refers to the first abdominal segment of an insect. It is a key anatomical structure in wasps, bees, and ants because it represents a fusion of body segments, giving a characteristic shape to these insects’ middle region. During development, the propodeum detaches from the abdomen and becomes fused with the last segment of the thorax. The exaggerated propodeal spikes in the major worker caste of Pheidole drogon are notable in light of the twin-flagged jumping spider’s mode of attack. This big-headed ant species is endemic to New Guinea, and constitutes an example of how a defensive adaptation can evolve through the co-option of a structure that originally evolved to overcome a different problem. Research shows
that reinforced muscle attachment points, which initially evolved to support the ants’ unusually large heads, have been co-opted to form spikes. This functional change was possibly driven by pressure from predators using similar hunting tactics as the twin-flagged jumping spider. Another notable feature of the propodeum is a significantly enlarged breathing pore called a “spiracle,” which connects to the respiratory system. The propodeal spiracle provides additional evidence that the segment originated in the abdomen.

In this footage, a pair of males engage in an approach that could lead to aggressive interaction. They appear to be practicing their display movements. The rivals vigilantly assess one another, ready to fend each other off by striking a threat pose, flinging their front legs up. Suddenly, with the arrival of a third individual, the interaction turns into a Mexican standoff. The newcomer confidently charges forward to drive the others away, without even bothering to put up a threat display.

nuptial gift

Practice makes it perfect. Eventually the male encounters a female and starts his courtship display. Here, a male is carrying out a series of ritualistic courtship movements, known as pre-mount tapping, using his forelegs. A male may try pre-mount tapping up to six times before accepting rejection. While the male is fully devoted to his act, the female can be seen holding an ant. This is when this observation gets all the more interesting. Ant hunting is a rare behavior, and whether it plays a part in this spider’s mating ritual is a curious matter. Ants do not offer much as food, but can be found easily and constitute a dependable snack. Males and females must be equally adept at snatching ants. The twin-flagged jumping spider does not offer nuptial gifts. Therefore, it is reasonable to conclude that the female hunted the ant herself, rather than receiving it as a present. Furthermore, ants are embarrassingly poor-quality resources in the context of a nuptial gift. On an interesting note, some argue that females may be using ants like a shield to keep unwanted males at a distance. From the male perspective, a female busy with a prey item might be especially attractive for males in reducing the cannibalism pressure coming from females.

Most jumping spider species don’t prey on ants. However, this behavior has evolved independently multiple times across different continents and in a small fraction of species. The unique combination of ant hunting ability and the mating ritual suggests an evolutionary pathway for this spider species to resolve the challenge of intraspecific predation.