AssetID: 55815480
Headline: Ant attack! Newly discovered spider uses ingenious 'catapult' to catch prey
Caption: **VIDEO AVAILABLE: CONTACT INFO@COVERMG.COM TO RECIEVE** BY MARK WORGAN A newly discovered spider species in the rainforests of northern Queensland, Australia has developed an extraordinary hunting strategy, using a spring-loaded silk trap to capture ants. Researchers say the nocturnal arachnid, nicknamed the "ballista spider", appears to specialise exclusively in hunting the aggressive green tree ant (Oecophylla smaragdina), employing a sophisticated silk mechanism that launches its prey into a waiting web. The discovery has been detailed in a study published in the journal Current Biology. Scientists believe the spider, which has not yet been formally named but belongs to the genus Propostira, may represent one of the most specialised predators known among spiders. The species was first observed by Professor Greg Anderson, a biomedical researcher, spider taxonomist and wildlife photographer. A team from Macquarie University, led by Professor Ajay Narendra and postgraduate researcher Pranav Joshi, spent 10 days and nights studying the spiders in rainforest near Cooktown in far north Queensland. Using high-speed and infrared cameras, they recorded the animal's unusual hunting behaviour in detail. Researchers say it is rare for spiders to prey on ants because of the risks involved. Green tree ants are known for their aggressive behaviour and use of chemical defences. They can rapidly summon large numbers of nestmates through alarm signals, making them potentially dangerous prey for solitary predators. During the day, the ballista spider remains concealed beneath leaves positioned above ant foraging routes. After nightfall, it descends more than half a metre and begins constructing an elaborate trap anchored to nearby vegetation or the forest floor. The spider may spend up to four hours creating the structure, which consists of dozens of tensioned silk strands arranged in a cone-shaped bundle close to the ground. To complete the trap, the spider wraps the silk cone in a finer layer of silk before retreating to a safe distance. When a green tree ant approaches, it reacts aggressively to the structure, biting the cone and inadvertently detaching it from its anchor point. The release triggers the trap, causing the tensioned silk to snap upwards and propel the ant more than 30 centimetres into the spider's web. Researchers found the prey experiences acceleration of more than 1,300 metres per second squared before becoming entangled. Only once the ant is securely trapped does the spider approach and immobilise it with silk. The team suspects the spider may add a chemical lure during the final stage of construction, encouraging the ants to attack the trap and trigger the mechanism themselves. Scientists say the hunting strategy appears unique because the web is designed to catch a single prey species and relies on the prey activating the trap rather than the predator. The spider's silk was analysed by researchers in Germany after samples were collected in Australia and examined using advanced imaging techniques, including scanning electron microscopy. The study found that the trap functions as a biological catapult, storing elastic energy within the silk before releasing it almost instantaneously. Researchers say the mechanism generates an exceptionally high power output, surpassing that of any other known silk-based biological catapult. This is particularly significant because green tree ants possess adhesive pads on their feet, meaning the trap must generate enough force to lift prey weighing several times more than the tension stored in the silk strands alone might suggest. Scientists believe the hunting method evolved as a highly specialised adaptation that enables the spider to capture dangerous prey while avoiding direct confrontation. By launching individual ants away from busy trails and nests, the spider can isolate and subdue them without risking retaliation from large numbers of workers. The researchers say the discovery provides a striking example of how predators can evolve highly specialised strategies to exploit a particular food source, highlighting the remarkable diversity of hunting behaviours found in the natural world. Further studies are expected to investigate whether the spider's apparent use of chemical signals plays a role in attracting its prey and triggering the trap.
Keywords: feature,photo,ants,spider,nature,science
PersonInImage: A ballista spider (Propostira sp.) sets and springs its trap for a green tree ant (Oecophylla smaragdina) to bite the cone of its web and thus spring the catapult-like snare.