The ogre-faced spider, from the genus Deinopis, is known for its distinct appearance and behavior. These spiders are nocturnal ambush predators with a highly specialized method of capturing prey. Found in tropical and subtropical regions, they have adapted unique biological tools to thrive in the low-light conditions of the forest understory.
Physical Characteristics and Habitat
Ogre-faced spiders have a long, slender, twig-like body. Their light brown or grey coloration provides camouflage, helping them blend in with low-lying vegetation during the day. Females are larger than males, with some reaching up to 30mm in body length. Their most prominent feature is the two enormous, forward-facing eyes that give them their common name. Despite their intimidating appearance, these spiders are not considered dangerous to humans.
These spiders are primarily found in the humid, tropical, and subtropical forests of Australia, Asia, Africa, and the Americas. They inhabit understory environments, often seen on the foliage of shrubs or palm fronds between one and four feet off the ground. This habitat provides a vantage point from which to spot prey moving on the forest floor.
The Net-Casting Hunter
The ogre-faced spider is a net-casting hunter. Shortly after sunset, the spider constructs a small, rectangular net from a specialized, wool-like cribellate silk. This bluish-white net is not sticky but is designed to entangle prey with its fuzzy texture. The construction process takes about half an hour, and if the net is damaged, the spider will build a new one.
Once the net is complete, the spider assumes an upside-down posture, hanging from a silk scaffold and holding the corners of the net with its front two pairs of legs. It waits for insects like ants, crickets, or other invertebrates to wander below. To improve its aim in the dark, the spider often deposits white fecal spots on the ground to use as targeting guides.
When prey is detected, the spider executes a swift and precise lunge. It stretches the elastic-like net to several times its original size and thrusts it downward to envelop the target. This rapid “casting” motion is a unique method among spiders, allowing it to actively capture prey. The spider then uses its powerful jaws to consume its meal.
Extraordinary Night Vision
The spider’s hunting success is directly linked to its night vision. Its two main posterior median eyes are the largest of any invertebrate relative to body size, with lenses that can measure up to 1.4 mm in diameter. These massive eyes give the spider a wide field of vision and an ability to gather light far surpassing that of nocturnal animals like cats or owls. This allows them to hunt in the near-total darkness of the forest floor.
This powerful vision is the result of a unique physiological process. Each evening, the spider produces a large, light-sensitive membrane within its giant eyes. Because the spider’s eyes lack an iris to control light intake, this membrane is rapidly destroyed by sunlight at dawn. This daily cycle of renewal means the spider grows a new retinal surface every night. During the day, its vision is not functional, restricting it to a nocturnal life.
Reproduction and Lifespan
Mating for ogre-faced spiders occurs in the late summer and early autumn. Following mating, the female constructs a distinctive egg sac. The sac is a tough, round ball, about 10 mm in diameter, with an intricately woven, ochre-brown exterior marked with dark flecks. She carefully camouflages the sac by attaching bits of leaves and twigs, suspending it in low vegetation where it resembles a small, woven purse.
The female guards the egg sac until the spiderlings emerge in the spring. After hatching, the young spiders remain together in a communal web for a short period before dispersing to begin their own solitary lives. The female may produce up to four egg sacs in her lifetime.