Tracking the Banana Spider

Welcome to Savannah, America's Most Beautiful City

 

 

 

 

 

 

 

 

 

Untangling a Web...
by David Gignilliat

 

 

 

 

 

 

 

I have never seen as many spiders in my life as I have in the last two years since I moved to Savannah. Specifically, the banana spider. Golden silk orb weavers, as they are also known. Or Nephila clavipes, for the arachnophiles out there.

They are as ubiquitous in downtown Savannah as the moss that hangs over our cobblestone streets. Walk around for a few minutes and youíll see them. Around the periphery of run-down homes and buildings. Near constructions sites for a new square and underground parking garage. On busy Savannah streets. In front of my house. Probably in my head too.

Now, Iím not necessarily afraid of these spiders, but I continue to be impressed (read: slightly afraid) by the size of these creatures and the breadth and complexity of their webs. Having nearly walked into a banana spiderís web recently on a quiet residential section of Liberty Street, I decided to investigate their biology further, with the help of the World Wide Web (pun intended). Maybe Iíd learn something about the behavior of these creatures, or even my own.

These non-poisonous arthropods gets their name from the color of their spider silk, purported to be the strongest silk in the world. Their golden-hued spiral webs alternately shine gloriously bright when in the sunlight (to attract bees) and lurk ominously in the shade (acting as a camouflage to trap unsuspecting insects or humans).

Chameleons by biology, necessity and disposition.
Duly noted.
Banana spiders demonstrate vibrational motion when approached by a predator, oscillating at approximately 40 Hz when its web is plucked. If a predator persists in an attack, the spider will either run to a web-support strand and thus to nearby vegetation, or bail out of the web on a silk line that remains connected to the web.
Shaking like a cell phone on vibrate, they are the ultimate survivors, experienced in both fight and flight. Thank goodness I didnít walk into that web.
The webs of banana spiders are tremendously complex, with a densely-spiraled orb levitating in an array of non-sticky barrier webs. The orbs are renewed nearly daily to maintain stickiness. The female banana spider, the menacing centerpiece of the orb, eats the portion to be replaced and builds new spirals. Positioned adjacent to one face of the main orb is usually a haphazard-looking network of guard-strands suspended a few inches distant across a free-space. This "barrier web" may serve several purposes Ė an early-warning system for prey or predators, a shield against leaves and twigs, a relics of a previous web, or even as a cue for birds to avoid flying into the web.
Their environment might be larger than you think. And if you tear down their web or accidentally saunter through it, the female spider will build it back up within a few days. Well-connected, you may be able to win the battle against the female banana spider, but not the war.
Typically, the male banana spider 1/5 the size of the female spider and is frequently oriented above and perpendicular to the female who hangs upside down. In some species, the female will often eat the male, but this is by no means a common occurrence. In fact, it is often the same males that court the female spider that are eaten. In the species that have been studied, mating occurs while the female is fresh from her last molt; this mating generally involves the dominant male which has been with the female for several days prior to the final molt. Later matings may occur while the female is eating (something else).
Hmmmm. The female spider is always the center of attention and is always more ornate and elaborate in its appearance than its male counterpart. Behind (or actually above and perpendicular) every good female spider is a good male spider. Or it could be the other way around. I guess it depends on the perspective. Sometimes she will eat the male, and for really no good reason. Usually, itís the same male sheís been dating. I wonder if she listens to Hall & Oates. ďWatch out boy, sheíll chew you up.Ē She is an effortless multi-tasker, capable of eating and mating at the same time. George Costanza would be proud.
Small male banana spiders are capable of copulating longer than the larger males and are more prodigious in the effectiveness of their fertilization. Both large and small males employ different mating techniques. The large ones cut a hole through the web and mate through that. The small ones visit the female directly. Empirical evidence suggests that small males usually mate at the first attempt, while large males struggle and often need several attempts for successful mating. Often, the presence and stimulation of a second copulating male spider promotes the release of sperm from the first copulating male spider. All copulation does not involve the release of sperm for the male banana spider. Either way, the female spider exhibits no outward preference for either large or small spiders.
Stay in school. Say no to drugs. Donít talk to strangers. Pay attention in biology class. I have nothing of value to add here. Really. Thatís my story and Iím sticking with it.
The mortal enemy of banana spiders in Savannah (in addition to unsuspecting humans and inanimate objects) are Argyrodes, a genus of very small black-and-silver spiders that are known as kleptoparasitic, or parasites via theft. Essentially, they steal the banana spidersí prey and starve it to death. According to a few websites, banana spiders have been known to have an almost manic (and irrational, if you ask me) fear of another one of Savannahís favorite sons, the palmetto. The cockroach's fast movements and large, dark shape cause some of these spiders to run from or ignore a perfectly delectable meal.
Finally, the banana spider reveals a weakness. A bug that doesnít like bugs. That doesnít make any sense. Of course it doesnít. Of course, things are not always what they seem, Öespecially when the scenery is moving fast.

Point is, Iíll be sure to carry a palmetto in my messenger bag at all times.

Capitalists have tried to use banana spiders for business purposes, attempting to make clothing and fishing lines from their silken threads. Ultimately, however, the thread-harvesting techniques have never been commercially sustainable (read:profitable).
The banana spider wins again.

Moral of the story. Lay off the threads man. Donít get eaten. If youíre not the lead spider, the web never changes. Stay away from cockroaches.
Pick your mates wisely.

Or just keep it simple and try to enjoy the tangled web they/we weave.

Questions, comments email editor@savannahbest.com

References:
http://frank.itlab.us/nephila_mating/nephila_competition.pdf
http://en.wikipedia.org/wiki/Banana_spider

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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