Spiders are creatures of intricate behavior and significant ecological roles. Their daily lives involve a diverse array of activities centered around survival, growth, and reproduction. Understanding what these arachnids “do all day” offers a glimpse into their fascinating adaptations and contributions to natural ecosystems.
The Daily Hunt: How Spiders Find Food
Hunting and feeding constitute a substantial portion of a spider’s daily routine, with various species employing distinct strategies to secure their meals. Orb weavers, for instance, construct large, circular webs, primarily at night. They wait in the center or hide nearby with a trip line, sensing vibrations when prey becomes ensnared. Once an insect is caught, the orb weaver quickly immobilizes it with venom and wraps it in silk for later consumption.
In contrast, active hunters like wolf spiders and jumping spiders do not rely on webs to catch prey. Wolf spiders possess excellent eyesight and agility, enabling them to stalk and pursue insects on the ground, often at night. They pounce on prey, holding it with their powerful legs before delivering a venomous bite. Jumping spiders, known for their keen vision, actively stalk their prey and then execute precise leaps to capture it.
Ambush predators, such as trapdoor spiders and crab spiders, employ different tactics. Trapdoor spiders construct burrows with hinged silk-and-soil doors, waiting to lunge out and capture unsuspecting prey that passes by. Crab spiders, on the other hand, often camouflage themselves on flowers, patiently waiting for insects to come within striking distance before grasping them with their legs and delivering a lethal bite.
Growth and Renewal: The Molting Process
Molting, also known as ecdysis, allows spiders to grow larger by shedding their rigid outer exoskeleton. This process happens periodically throughout a spider’s life, more frequently when young and less often as they mature. Before molting, a spider stops feeding and may become less active, often seeking a secluded or protected location.
The molting process involves three main stages: pre-molt, during molt, and post-molt. During pre-molt, the spider’s body reabsorbs some of the old cuticle and begins secreting a new, folded exoskeleton underneath. When ready, the spider increases its internal fluid pressure, causing the old exoskeleton to crack, often around the cephalothorax. The spider then extracts itself from the old shell, a process that can take minutes to days depending on the species.
Immediately after molting, the new exoskeleton is soft and flexible, making the spider vulnerable to injury or predation. Many species hang from a silk thread or remain in a protected silk retreat during this time. The new exoskeleton gradually hardens over several days to a week, during which the spider remains inactive and does not feed. This renewal process is important for growth and can even allow spiders to regenerate lost limbs over successive molts.
Beyond the Hunt: Resting, Hiding, and Home Life
Spiders engage in various activities beyond hunting and molting, including resting, hiding, and maintaining their living spaces. Resting is an important behavior for energy conservation, as spiders have efficient metabolisms that allow them to survive for weeks or even months without food. By remaining still, they reduce their energy expenditure significantly. This stillness also serves as a defensive mechanism, making them less noticeable to predators.
Maintaining their “homes” is another important daily task, particularly for web-building species. Orb weavers, for example, are often nocturnal and spend their nights repairing or even entirely rebuilding their circular webs. This ensures the web remains effective for catching prey and can involve consuming old silk to reclaim moisture and nutrients. For species that reside in burrows, like wolf spiders, maintaining the integrity and security of their underground retreats is a continuous effort.
Spiders also spend much time hiding from potential threats. Many hunting spiders, such as wolf spiders, conceal themselves under rocks, leaves, or within burrows during the day to avoid predators. This defensive behavior is just as important as hunting for their survival. These periods of inactivity are not merely downtime but are important for their long-term survival and energy management.
The Next Generation: Reproduction and Rearing Young
Reproduction is an important, albeit periodic, aspect of a spider’s life cycle, encompassing courtship, mating, and the care of offspring. Male spiders often undertake complex courtship rituals to signal their species and intentions to females, often to avoid being mistaken for prey. For instance, male web-building spiders may pluck threads of a female’s web in a rhythmic pattern, while wolf spiders and jumping spiders might perform visual displays involving leg waving or dances.
After successful courtship, mating occurs, where the male transfers sperm to the female, often using specialized appendages called pedipalps. Females can store sperm for extended periods, even up to a year, before laying eggs. Female spiders then construct silk egg sacs, which vary widely in appearance and can contain from a few to thousands of eggs, depending on the species. These sacs provide protection for the developing eggs from predators and environmental hazards.
Parental care among spiders varies significantly. Many female spiders guard their egg sacs, either by hiding them in secure locations, attaching them to objects, or carrying them directly. Wolf spider mothers, for example, carry their egg sacs attached to their spinnerets and, after hatching, the spiderlings may ride on their mother’s back.
While most spiderlings are independent upon emergence, some species exhibit extended maternal care, occasionally even feeding their young. In rare cases, paternal care has also been observed in some solitary species, where males protect egg sacs. Once spiderlings emerge, they disperse, sometimes by “ballooning,” where they release silk threads to be carried by the wind to new locations.