Darwin's bark spider
Encyclopedia
Darwin's bark spider is an orb-weaver spider
that produces one of the largest known orb webs, web size ranged from 900–28,000 cm2 ,
with anchor lines spanning up to 25 metres (82 ft). The spider was discovered in Madagascar
in the Andasibe-Mantadia National Park
in 2009. The species was named in honour of the naturalist Charles Darwin
, with the description being prepared precisely 150 years after the publication of The Origin of Species
, on 24 November 2009.
Its silk is the toughest
biological material
ever studied, over ten times tougher than a similarly-sized piece of Kevlar
. The average toughness of the fibres is 350 MJ/m3, and some are up to 520 MJ/m3, making the silk twice as tough as any other spider silk known.
The web of Darwin's bark spider is remarkable in that it is not only the longest spanning web ever observed, but is among the largest orb webs ever seen, at an area of up to 2.8 square metres (3.3 sq yd). Nephila komaci
, discovered in 2009, and some other Nephila species also make webs that can exceed 1 m (3.3 ft) across.
According to professor Ingi Agnarsson, director of the Museum of Zoology at the University of Puerto Rico
, the spider's web occupies a unique biological niche: "They build their web with the orb suspended directly above a river or the water body of a lake, a habitat that no other spider can use". This position allows the spiders to catch prey flying over the water, with webs observed containing up to 32 mayflies
at a time. The strong silk and large web are thought to have coevolved at the same time, as the spider adapted to the habitat. Scientists are currently researching how the spider is able to weave such a large web over water along with being able to anchor drag lines on either side of a river.
Like other spiders of the genus, Darwin's bark spider displays extreme sexual dimorphism
, with large females (18 mm) and small males (6 mm).
The spider was described along with a previously undescribed species of fly, which appeared to have a kleptoparasitic
relationship with it. The flies often feed on the spider's catches before the spider wraps them. Occasionally, spiders have been observed to chase away the flies when they land on something that the spider is eating.
Orb-weaver spider
The "typical" orb-weaver spiders are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields and forests...
that produces one of the largest known orb webs, web size ranged from 900–28,000 cm2 ,
with anchor lines spanning up to 25 metres (82 ft). The spider was discovered in Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
in the Andasibe-Mantadia National Park
Andasibe-Mantadia National Park
Andasibe-Mantadia National Park is a 155 square kilometre protected area consisting principally of primary growth forest in Alaotra-Mangoro Region in eastern Madagascar. The park's elevation ranges from 900-1250 meters, with a humid climate. Average annual precipitation is 1700 mm, with rainfall...
in 2009. The species was named in honour of the naturalist Charles Darwin
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
, with the description being prepared precisely 150 years after the publication of The Origin of Species
The Origin of Species
Charles Darwin's On the Origin of Species, published on 24 November 1859, is a work of scientific literature which is considered to be the foundation of evolutionary biology. Its full title was On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the...
, on 24 November 2009.
Its silk is the toughest
Toughness
In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing; Material toughness is defined as the amount of energy per volume that a material can absorb before rupturing...
biological material
Biomaterial
A biomaterial is any matter, surface, or construct that interacts with biological systems. The development of biomaterials, as a science, is about fifty years old. The study of biomaterials is called biomaterials science. It has experienced steady and strong growth over its history, with many...
ever studied, over ten times tougher than a similarly-sized piece of Kevlar
Kevlar
Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...
. The average toughness of the fibres is 350 MJ/m3, and some are up to 520 MJ/m3, making the silk twice as tough as any other spider silk known.
The web of Darwin's bark spider is remarkable in that it is not only the longest spanning web ever observed, but is among the largest orb webs ever seen, at an area of up to 2.8 square metres (3.3 sq yd). Nephila komaci
Nephila komaci
Nephila komaci is a species of golden orb-web spider. It is the largest web-spinning spider known. A few specimens have been found in South Africa and Madagascar.-Discovery:...
, discovered in 2009, and some other Nephila species also make webs that can exceed 1 m (3.3 ft) across.
According to professor Ingi Agnarsson, director of the Museum of Zoology at the University of Puerto Rico
University of Puerto Rico
The University of Puerto Rico is the state university system of Puerto Rico. The system consists of 11 campuses and has approximately 64,511 students and 5,300 faculty members...
, the spider's web occupies a unique biological niche: "They build their web with the orb suspended directly above a river or the water body of a lake, a habitat that no other spider can use". This position allows the spiders to catch prey flying over the water, with webs observed containing up to 32 mayflies
Mayfly
Mayflies are insects which belong to the Order Ephemeroptera . They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies...
at a time. The strong silk and large web are thought to have coevolved at the same time, as the spider adapted to the habitat. Scientists are currently researching how the spider is able to weave such a large web over water along with being able to anchor drag lines on either side of a river.
Like other spiders of the genus, Darwin's bark spider displays extreme sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
, with large females (18 mm) and small males (6 mm).
The spider was described along with a previously undescribed species of fly, which appeared to have a kleptoparasitic
Kleptoparasitism
Kleptoparasitism or cleptoparasitism is a form of feeding in which one animal takes prey or other food from another that has caught, collected, or otherwise prepared the food, including stored food...
relationship with it. The flies often feed on the spider's catches before the spider wraps them. Occasionally, spiders have been observed to chase away the flies when they land on something that the spider is eating.