Spiders possess fangs, specialized structures fundamental to their survival. These essential tools are primarily used for capturing prey and for self-defense. Fangs are a defining characteristic, enabling spiders to interact with their environment and obtain food.
Anatomy of Spider Fangs
Spider fangs are sharp, pointed appendages located at the end of their chelicerae, which are the spider’s mouthparts. Each chelicera consists of a stout basal segment and a smaller, movable fang at its tip. The fangs are typically hollow or grooved, functioning much like hypodermic needles. This design allows for the efficient delivery of venom.
Almost all spider species possess fangs. Venom glands, which produce the venom, connect to these fangs via a thin duct. These glands can be located within the chelicerae’s basal segment or extend into the spider’s cephalothorax, its fused head and thorax region. Fangs are composed of a bio-composite material, primarily chitin (a carbohydrate also found in insect exoskeletons) and various proteins. Their microscopic structure and curvature contribute to their stiffness and ability to effectively pierce prey.
The orientation of chelicerae and fangs varies among spider groups. Mygalomorph spiders, which include tarantulas, have fangs that are positioned to swing forward and downward, similar to an axe. In contrast, araneomorph spiders, which represent the majority of spider species, have chelicerae that swing towards each other in a pincer-like motion. This difference in orientation impacts how they engage with prey.
How Spiders Utilize Their Fangs
Spiders primarily use their fangs to inject venom into prey, immobilizing or killing it. When biting, a spider squeezes venom from its glands through the hollow fangs into the target. The venom acts rapidly, often containing neurotoxins that affect the prey’s nervous system, leading to paralysis. Some venoms also contain enzymes that begin external digestion, liquefying the prey’s internal tissues before consumption.
Beyond venom injection, fangs also play a role in physically holding and manipulating prey. Some spiders may wrap their prey in silk to further subdue it or make it easier to transport. The amount of venom injected can vary depending on factors such as prey size and how much the prey struggles, showing control over venom delivery.
Fangs also serve a secondary function in defense against predators or perceived threats. While almost all spiders are venomous, only a small number have fangs strong enough or venom potent enough to pose a significant threat to humans. Most spider bites to humans are rare and result in only mild, localized reactions. Serious injuries from spider bites are uncommon and are mainly associated with a few specific types, such as widow spiders and recluse spiders.