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Spiders!

By Bonnie Hamre, About.com Guide

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Spiders, ugh, double ugh. Creepy crawlies, they give me the willies. Shudder.

Now I know that’s not the objective way to look at them, and spider aficionados will praise their qualities and even their beauty. They might roll their eyebrows and look down at me, but every time one appears on-screen during the Survivor episodes, I have to look away.

Nonetheless, they are part of the environment the Castaways are in, and worthy of a closer look. I have no idea what they are, but see these photos of some of the common spiders in Panama:

silvery brown spider

pinkish spider on a leaf

tarantula?

Panama is known for its wide variety of spiders, and scientists come to the country to study them. Books, such as The Spiders of Panama and articles , such as Proceedings of the Royal Society B: Biological Sciences have been written about them.

One of the spiders mentioned in the article is the Argiope argentata: “Many orb-weaving spiders decorate their webs with extra, bright white, ultraviolet light reflecting silk. Previous studies suggest that these decorations increase a spider's foraging efficiency by improving web attractiveness, which is known as the prey-attraction hypothesis. One assumption of this hypothesis is that individuals which decorate their webs at a higher frequency are expected to have a higher growth rate. Using a decoration-building orb-weaving spider, Argiope versicolor, I show a strong positive relationship between the growth rate in terms of weight gain and the frequency of decoration-building, as well as the rate of insect interception. This is the first study to reveal a fitness consequence of decorating behaviour in spiders.”

The book, by Wolfgang Nentwig in collaboration with Bruce Cutler and Stefan Heimer, discusses “The” 1200 species of spider currently known from the area probably represents only about 60 percent of the species diversity existing there, even so it is a lot of species and it comes as know surprise to discover that this work does not attempt to offer identification to species level. The species catalogue lists all 1200 species but the keys only go as far as genera or sometimes only to family. The work is however greatly enhanced in my view by the addition of a largish introduction which supplies loads of interesting information on the Panamanian fauna.

All spiders have certain things in common:

They are arachnids, a group of arthropods that also includes scorpions, harvestmen, mites, and ticks.

They have jointed legs , a hard external or outer skeleton and four pair of legs. They have no wings or antennae, but have enlarged, sharply pointed jaws called fangs (chelicerae).

They are predators, feeding on a wide variety of insects and other soft-bodied invertebrate animals. Spiders attack and subdue their prey by biting with their fangs to inject a poison. As predators, spiders are beneficial.

They spin silk, some to protect their eggs, others to make a parachute and some to make a web.

They are poisonous. Most are either too small or possess poison that is too weak to harm humans. Only a few have bites that are dangerous to humans. However, the bite of these few species can cause serious medical problems and possible death under certain circumstances. Here’s what to do if you get a spider bite . As stated, there are many varieties of spiders in Panama and Latin America.

Panama blonde (psalmpopoeus pulcher) - This arboreal native is said to be less aggressive than other members of its genus. Arboreal, but will burrow some, especially as spiderlings

banana spider

The largest known spider in the world is Goliath bird-eating spider from South America (Surinam, Guyana and French Guinea). Its scientific name is Theraphosa leblondi and it can have a legspan of up to 28 cm (11 ins). It is an aggressive spider and though available in many pet shop should not be kept as a first spider pet. The largest specimen recorded was a male, though females are heavier, they tend to have shorter legs.

The smallest known spider in the world also comes from South America, a fully adult male Patu digua from Colombia measures about 0.37 mm (0.015 in). Welcome to the Octopodal World of Spiders

Brazilian Wandering Spiders are extremely fast, extremely venomous, and extremely aggressive. These large and dangerous true spiders are ranked among the most venomous spiders known to man.