Huntsman Spider: Apex Predator in a Microhabitat

Under cover of darkness, a predator slowly emerges from the shadows to stalk an unsuspecting night-time forager. The forager senses an eerie presence and makes a run for it. The speed of the scuttling prey, however, is no match for the agile predator. The chase ends in seconds with the prey in a firm grip, and a fatal bite is delivered. Just as the predator begins to eat its prize catch, a human flicks on a switch. In an instant, a bright light fills every corner of the predator’s tiled habitat. The predator, seemingly annoyed with the human, slowly drags her prey behind the safe cover of a toilet bowl. Through my time living in the Nilgiris, nightly visits to the loo were suspiciously similar to hunting sequences from 90s nature documentaries. The only subtle differences were that a huntsman spider (Heteropoda venatoria) played the role of predator instead of a big cat, and the background score of calling peacocks was replaced by a quartet of chirping crickets. On most nights, I would see the spider chomping down on a sizeable serving of cockroach. Other nights, I would wonder

One of the most conspicuous features of the huntsman in my bathroom was her speed. Huntsman species like H. venatoria can move at speeds of over 1m/s-1! Quite impressive when you consider that an animal no larger than your cell phone is moving as fast as most humans walk. Their speed allows them to chase down and hunt a wide array of prey with relative ease. Between regular cockroach dinners, my housemate preys on a house gecko, crickets that I have had trouble catching, and the odd moth. This last group of flying prey got me briefly wondering, “How does a ground-dwelling huntsman catch a flying moth?” For starters, you soon realise that these spiders are not strictly ground-dwelling. They regularly scale walls and run across them with little regard for the laws of gravity. In addition to their vertical prowess, research has shown that Heteropoda venatoria possesses another secret weapon — an irresistible moustache. A study conducted by Shichang Zhang et al. found that the white moustache-like stripe on the head of H. venatoria has reflective properties that attract nocturnal prey, particularly moths.

While most encounters between huntsman spiders and humans tend to be in urban settings, these spiders live in a diverse range of habitats across the tropics and warm temperate regions of the world. The common name “huntsman” applies to the entire Sparassidae family, which comprises nearly 1,400 species of spiders. This diverse and widely distributed group of hunters also comes in various sizes and colours to match their microhabitats and ecological niches. The genus Gnathopalystes, for instance, are huntsman spiders that live and hunt on plants. Their vibrant green colour lets them blend in with the hues of their leafy abodes. Spiders in the genus Pandercetes live on tree trunks and take camouflage to surreal levels. These spiders have evolved in morphology and behaviour (staying perfectly still) to merge seamlessly with the barks of trees. Their colours and textures often resemble a patch of lichen growing on a tree trunk, earning this genus the common name, lichen huntsman. In Australia and New Zealand, the species Delena cancerides has found strength in numbers. Colonies of up to 300 spiders work together to capture prey and care for their young.

Like most spider families, a reliable way to identify this huntsman family is by looking at their characteristic eye arrangement — this is possible even for an enthusiast with a macro lens.

Deep in the caves of Laos, however, lives a huntsman (Sinopoda scurion) that adds refreshing diversity to the question, “How many eyes does a spider have?” S. scurion has none! In its cave habitat, where there is no natural light and vision is of little use, this species of huntsman evolved to have no eyes. Images of this spider’s head seem like somebody went a bit too far with the “red-eye removal” feature on an otherwise ordinary picture of a huntsman. However, where it lacks eyes, the cave-dweller makes up with sharp tactile senses, painting a picture of the world around it through vibratory cues. The acutely sensitive hair on its legs and body detect slight movements on the ground. Each strand connects to nerves that relay information. A central nervous bundle then makes sense of these relays in multiple ways — the direction of the vibration, the potential size of the object causing it, and a wealth of other information.

Whether they are seemingly unfavourable environments like a pitch-black cave or unnatural spaces like a tiled bathroom, evolution finds a way to create ecosystems and weave in the complexities of life. After many months of watching the huntsman in my room act as an apex predator, I watched her lifeless body being carried away by an army of ants. Outside my room, parasitoid wasps like Tachypompilus sp. would regularly paralyse huntsman spiders and use the spiders’ large bodies as edible nurseries for hungry young wasps. Huntsman spiders are voracious hunters and, if wasps are to be believed, a sumptuous meal for hatchlings. Waiting to be met in the comfort of our own homes; they are predators of some, prey for others, and storytellers of the delicate balance of life.