Carbon Chemist

Tag: spiders

  • Spiders use fireflies as flashing lures to catch more prey

    Spiders use fireflies as flashing lures to catch more prey

    [ad_1]

    An orb-weaver spider wraps up its flashing prey

    Xinhua Fu

    Once orb-weaver spiders ensnare male fireflies in their webs, they turn the doomed insects into bait, using their telltale flashing to lure in more meals.

    Xinhua Fu at Huazhong Agricultural University in China noticed male fireflies (Abscondita terminalis), but no females of the species, often got stuck in the web of an orb-weaver spider (Araneus ventricosus), and he wondered if the male insects were being lured into the trap. Both males and females of this firefly species use flashing signals in courtship, and females’ light shows attract males to their location. So Fu and his colleagues investigated how the spiders might be exploiting this love language.

    In a stretch of farmland in Hubei Province, China, the team ran a series of experiments on 161 different webs, some with and some without spiders. The researchers placed a male firefly – some of which had their bright abdomens blacked out with ink – in each web. They found webs with both a spider and a freely flashing firefly attracted more male fireflies, compared to webs with no spiders present or with only non-flashing fireflies.

    Also, the male fireflies entangled in a spider-occupied web had an unusual flash signal. It looked more like that of females, with one pulse instead of two. But fireflies in an empty web flashed normally.

    This suggests the spiders are manipulating the male fireflies’ signals to mimic those of females, luring in other males searching for mates, says team member Daiqin Li at Hubei University. Precisely how the spider alters its immobilised prey’s signals is still unknown, but the researchers have some ideas.

    “The spider’s venom or the bite itself may lead to changes in the ensnared males’ flashing pattern,” says Li.

    Li is interested in seeing if other firefly-eating spiders use a similar tactic. Other animals may use captured prey as lures by capitalising on different types of signals, he says, such as sounds or the release of pheromones.

    “[The findings] once again demonstrate that spiders are not passive foragers,” says Mariella Herberstein at Macquarie University in Australia. “We are discovering more and more cases of highly complex and selective feeding techniques.”

    Topics:

    [ad_2]

    Source link

  • Male and female spiders pair up to look like a flower

    Male and female spiders pair up to look like a flower

    [ad_1]

    A brown male Thomisus guangxicus spider, centre, and a pale amber female female just below, among Hoya pandurata flowers

    Shi-Mao Wu

    A species of spider found in China may have evolved so that a male-female pair together resembles a flower, helping them blend in with their background.

    “This may be the world’s first case of cooperative mimicry,” says Shi-Mao Wu at Yunnan University, who made the observation with his colleague Jiang-Yun Gao.

    Spiders from the Thomisidae family, also known as crab spiders, are ambush predators that usually live on or near flowers.

    They are known for their great camouflage abilities, which prevent them from being spotted by their prey or predators. Some species can even change their colour to match that of the flower they are sitting on.

    Wu and Gao were in a tropical rainforest in Yunnan province in south-west China when a male crab spider of the Thomisus guangxicus species caught Wu’s attention. The spider was sitting on a flower of Hoya pandurata, an plant that lives on the forest’s ancient tea trees.

    “When I first observed the male spider, I did not observe the female spider,” says Wu. Only when he got closer did he notice that the male spider was lying on the back of a female. “They successfully deceived my eyes,” he says.

    The researchers hypothesise that the smaller and darker male might mimic the pistil – the female organs in the centre of the flower – while the female mimics the fused petals.

    They only match the appearance of the flower when individual spiders of both sexes come together, the researchers say.

    However, Gabriele Greco at the Swedish University of Agricultural Sciences isn’t convinced. “It is very difficult to establish the nature of the behaviour that has been observed,” he says.

    In fact, during mating, it is common in many spider species for the males to stand on top of the females. “The easier explanation could be a simple interaction linked to courtship and mating,” says Greco.

    Topics:

    [ad_2]

    Source link