Grace Kioko is Kenya’s veritable spider woman. She is the author of Kenya’s first check list of spiders.
In a recent presentation at Nature Kenya, Kioko revealed the little-known world of Kenya’s 805 species that have been documented to date.
A research scientist in the Zoology department at the National Museums of Kenya, she holds a Master’s degree in Ecology from the University of Chinese Academy of Sciences.
Of the documented 805 species of spiders in Kenya, 300 are “only found in Kenya”. Spider species around the world number 49,713 to date.
Spiders are identified from their eye patterns and you can tell the sexes from the palp. Males support the two palpal bulbs — also known as genital bulbs, borne on the last segment of the front ‘limbs’ to transfer sperm to the female.
Thirty out of the 805 species of Kenya’s spiders known to date are venomous. So you are quite safe except for a painful bite.
Spinning a web
The spider’s trademark is its web. Kioko says that besides the eyes giving away the species of the arachnida, spiders can be identified from the spin of the web — orb, funnel, shaded or mesh — and that they have hunting techniques and food preferences.
Some lay traps, while others spin strong webs and when disturbed, the spider rushes to devour the prey. There are spiders that eat small fish and others that prefer butterflies. Interestingly, some spider species mimic other animals. There is one that morphs into a ladybird and another that looks like an ant.
Pest control
“If spiders disappeared, we would face famine,” said Norman Platnick of New York's American Museum of Natural History, making a case for spider conservation. Platnick was curator emeritus of the division of invertebrate zoology for the American Museum of Natural History (AMNH) in New York, which holds the world's largest spider collection.
He added 158 genera and 2,023 species to the taxonomic database, and helped expand the known world of spiders to 48,000 species. Until 2014, he maintained the World Spider Catalog, a website formerly hosted by the AMNH which tracks arachnology literature, which has a comprehensive list of every species of spider that which has been formally described.
“Spiders are the primary controllers of insects,” continues Kioko. “They eat the pests that would otherwise eat all our crops.” If all farmers appreciated this free pest-control service, it would save them money from buying pesticides which with constant use end up in our digestive system and that of other animals. It would also save the soil from being contaminated from the chemicals.
Spiders can go long periods without food. They can also prey on each other.
Spiders are also of great economic importance other than being natural pest controllers.
Darwin's bark spider, discovered in Madagascar in 2009, produces the largest known orb webs, ranging from 900 to 28,000 square centimetres. Its silk is toughest biological material ever studied.
The people of Madagascar have been weaving a beautiful textile from the golden orb-weaving spiders for centuries.
Weaving textiles
In 2009, some 70 people spent four years collecting golden orb spiders from telephone poles in Madagascar while another dozen workers carefully extracted about 24 metres of silk filament from each of the arachnids. The resulting 3.3m by 1.2m textile is the only large piece of cloth made from natural spider silk existing in the world today.
The fabric was displayed at the American Natural History Museum in New York in 2009.
Threatened
Today, the spiders’ silk is used in medicine for repairing ligaments and tendons. The fibre is also used in bullet-proof vests and manufacturing air-bags for vehicles.
Like all wildlife, spiders face the same challenges such as habitat loss and poisonous pesticides. According to Kioko, six species of spiders in Kenya are threatened.
So next time you see a spider in the kitchen, leave it alone. Let it hunt the mosquito
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