Have you ever seen a spider’s web with an insect wrapped in silk? It’s a creepy but common sight. As you take a closer look, you may wonder why spiders go through the trouble of wrapping their prey.
Spiders have some ingenious reasons for encasing their meal in silk. Let’s unravel the mysteries of this behaviour and see how it benefits spider survival.
Why Do Spiders Wrap Their Prey?
Spiders wrap their prey for several key reasons:
To Store Food For Later
Spiders don’t eat their prey straight away. They often wrap insects in silk and hang them on the web to snack on later. This allows the spider to trap multiple insects before stopping to eat.
Wrapping prey also keeps it fresh longer. The silk acts as a natural refrigerator, slowing down decomposition. This lets the spider enjoy a few meals from one capture.
To Restrict Prey Movement
The wrapping silk prevents insects from wiggling free or fighting back. The tight binding secures the prey firmly, keeping the spider safe from counterattack.
This is especially important for dangerous prey like wasps or bees that could sting the spider. Tight wrapping neutralizes these threats.
To Disarm and Weaken Prey
As spiders wrap an insect, the tight silk “retrains” it. This disarms the prey and prevents it from using its appendages or defences.
The tight binding can weaken or crush the insect as the spider layers more silk. The spider then has an easier time killing and liquidating the prey item.
For Transport Back To The Nest
Some spiders don’t eat their prey directly on the web. They haul it back to a nest or crevice to consume in safety.
Wrapping insects in silk makes them easier to carry. The spider can trek across walls and ceilings with its packaged snack firmly in tow.
To Store For Egg Production
Female spiders also wrap prey to stockpile food for producing eggs. The extra nutrients help them generate more healthy eggs faster.
Plus, stored food fuels female spiders while they protect their egg sacs. Having readily available prey nearby means mother spiders don’t have to leave their eggs.
How Do Spiders Wrap Their Prey?
Spider species have different techniques for encasing prey, but the basic process is similar:
Step 1) Secure The Prey
First, the spider needs to immobilize its prey fully. It does this by:
- Biting venom into the insect to sedate or kill it
- Using silk to tie down appendages so it can’t escape
Step 2) Start Wrapping Base Layers
Next, the spider discharges silk from its spinnerets (silk glands) and begins covering the prey. The initial layers anchor the insect firmly in place.
Step 3) Add Outer Layers
The spider keeps rotating and layering on more silk. This further restricts the prey’s movements and covers any exposed body parts.
Step 4) Suspend Or Stash
Finally, the spider will suspend its wrapped prize in the web or carry it off to stash it somewhere safe. The packaging process is complete!
Spiders are masters at adjusting their wrapping techniques. Some significant variations include:
- Loose wrapping – Some spiders quickly thread around prey to restrain it. No further processing is needed!
- Tight wrapping – Other spiders do a full mummy-style wrap, circling silk over and over until the prey is fully bound.
- Partial wrapping – Spiders like the Black Widow often wrap an insect’s thorax and head. This leaves the tastiest abdomen exposed for easy eating access later.
- Web wrapping – Some spiders grapple and subdue prey first, then haul it to the edge of the web for wrapping. Others do the entire attack and wrapping process in the web’s centres.
Why Are Some Spiders Better At Wrapping Than Others?
All spiders can spin silk from their abdomen, but not all are adept at bundling prey. Some common factors that make certain species superior wrappers include:
Web Structure
Spiders with dense, non-sticky webbing do their wrapping right on the web. But spiders whose webs are meant solely for capturing prey need to haul it to the outskirts before wrapping.
Body Size
Tiny spiders can’t wrangle large prey. Larger spiders have the size and strength advantage of handling bigger insects and securing them in silk.
Venom Potency
Spiders with stronger venom can quickly immobilize insects, making moving easier without interruption. Weaker venom means more effort in keeping prey contained.
Silk Production
Some spiders don’t spin enough silk to do efficient wrapping. Prolific silk producers can encase prey in thick layers faster.
Orb weaver spiders like the Argiopes are champion wrappers, using size, venom and lots of silk to their advantage. Jumping spiders excel at wrapping, too, thanks to potent venom and web versatility.
Meanwhile, ambush and sac spiders with less web presence wrap minimally or not at all. Their recreational wrapping skills just never advanced in the same ways.