Athena and Arachne
The Myth of Arachne
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Anatomy of Spiders
Jumping Spider vision
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Athena and Arachne
The Myth of Arachne
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Anatomy of Spiders
Jumping Spider vision
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From Spider Silk Leslie Brunetta and Catherine L Craig
Scientists and entrepreneurs have spent millions of dollars trying to copy what spiders accomplish in a budget of dead bugs. (x)Without undergoing major outward bodily change since they first evolved, spiders have nonetheless adapted to a vast array of conditions. (xii)
When spiders use silk as trip lines or webs, they are able to extend their energy, their senses, and even their physical reach without changing the outlines of their anatomy... (xiii)
Spiders that have evolved more recently... have 6 or more different silks at their disposal. Each is produced from a dfifferent type of gland and used for a different purpose. (xiii)
Silk is a protein, a substance made from highly complex molecules... constructed from ... amino acidsd. Different combinations of amino acids give rise to different proteins, each with specific properties (xiii)
Multimodal Communication in Wolf Spiders (Lycosidae) — An Emerging Model for Study
Uetz, Clark, Roberts
...Spiders communicate with each other using a variety of sensory modalities (chemical, vibratory, visual) in multiple contexts (courtship, aggression, social behavior)....The subject of communication in spiders is of growing interest to animal behaviorists and evolutionary biologists for many reasons. Communication is critical for spiders, as they are predatory and potentially cannibalistic and thus positioned uniquely at the intersection of sexual and natural selection. Spiders have a very different sensory world, or "umwelt" than better-studied taxa (such as vertebrates and insects) and perceive their world through substratum vibration (eg, environmental surfaces or the silk strands of webs), chemotactile or olfactory cues (eg, silk-borne or airborne pheromones), and widely varying visual capabilities (ranging from rudimentary light/dark perception to high-resolution visual acuity). Perhaps as a consequence, spiders exhibit a great diversity of communication behaviors. Spiders also have a relatively simple central nervous system (CNS), yet they can integrate sensory input from multiple sources and systems at the same time.
Portia Perceptions: The Umwelt of an Araneophagic Jumping Spider (pdf)
Duane P. Harland and Robert R. Jackson
Spiders are traditionally portrayed as simple, instinct-driven animals (Savory, 1928; Drees, 1952; Bristowe, 1958). Small brain size is perhaps the most compelling reason for expecting so little flexibility from our eight-legged neighbors. Fitting comfortably on the head of a pin, a spider brain seems to vanish into insignificance. Common sense tells us that compared with large-brained mammals, spiders have so little to work with that they must be restricted to a circumscribed set of rigid behaviors, flexibility being a luxury afforded only to those with much larger central nervous systems......Web-building spiders have only rudimentary eyesight (M. F. Land, 1985a), and so use the information provided by web signals as a primary source of sensory information (Masters et al., 1986; Foelix, 1996). Hence the web itself can be thought of as an integral part of a typical web-builder’s sensory system (Witt, 1975)...
It is really their unique, complex eyes that set this family of spiders [Portia] apart from all others. Among spiders (many of which have very poor vision), salticids have eyes that are by far the most specialized for resolving fine spatial detail... As do all salticids, Portia trails a line of silk, called a dragline, behind it as it walks...
Umwelt, Biology, and Bio-Politics: A Foray into Uexküll's World (from humanimalia.org)
in Jakob von Uexküll. A Foray into the World of Animals and Humans, with A Theory of Meaning
Minneapolis: University of Minnesota Press, 2010. 248 pp. $25.00.
Uexküll considers the relationship of spider and fly: the spider does not and cannot "know" the fly in a comprehensive objective sense, and yet the dimensions of the spider's web are attuned in a delicate fashion to the proportions of the fly's body. The trap that the spider sets is sensitive to the fly's perceptual apparatus, moreover, even to the point of crafting its strands in such a manner that they become invisible to the fly's eye. As Agamben comments in a chapter of his work The Open, "The two perceptual worlds of the fly and the spider are absolutely uncommunicating, and yet so perfectly in tune that we might say that the original score of the fly, which we can also call its original image or archetype, acts on that of the spider in such a way that the web the spider weaves can be described as 'fly-like'" (Agamben 42). The circuitry of perception and effect marks turns out to be variegated and flexible enough to knit together the life processes of many beings, even above and beyond their individuated horizons of understanding. To say that the spider wills an innovation in web-making that consciously accommodates the archetype of the fly is to misunderstand its cognitive power; it is something like presuming that the tick wills an especially selective olfactory sense to attune itself to the mammals that pass beneath it. In both cases, there is an operative logic at work, and one that makes fascinatingly rapid adaptations, considering the constantly changing nature of biological forms, as well as the larger dynamic biosphere in which they live. This logic is one that emerges from within the formal life of interdependent organisms, and is meaningful because of that frame, but it gains its holistic sense from a larger and more encompassing principle. That principle, moreover, stands above and beyond human perception which is itself limited and constrained by means of its own Umwelt.
Umwelt: Zilla diodia (arachnophilia.net)
von Uexküll:I would be very astonished if a tailor made a suit that fit me without taking my measurements or first fitting me with it. I would assume that he had obtained my correct measurements from his own body, because all human bodies look alike on the whole. Because of this fact, ready-to-wear suits can fit one; they reproduce the normal proportions of the human body in various sizes. Every tailor's shop, therefore, is a gallery of hollow shapes of the human body.In the case of the spider, however, these prerequisites do not occur — and yet, it is possible for the spider successfully to fit the web to the hollow shape of a fly. It uses this hollow shape not in the fly's interest, but to destroy it. In the spider's Umwelt the web represents a meaning-utilizer of the meaning-carrier 'prey'.
The meaning-utilizer is attuned exactly to the meaning-carrier, so that one can designate the spider's web as an image of the fly.
The spider as tailor reproduces the fly's image without the human tailor's tools. The spider cannot take measurements of its own body to build the web, because its shape differs completely from the fly's shape. Nevertheless, it spins the size of the mesh to accord with the size of the fly's body. It measures the strength of the web's threads to resist the force of the insect in flight. The radial threads of the web are spun tighter than its circular threads, which yield slightly, enclosing the fly and entangling it in their sticky droplets. The radial threads are not sticky; they serve the spider as the shortest route to the captured prey. The fly is then rendered powerless by a web the spider spins around it.
Spiders' webs are mostly to be found in 'runways' of flies.
A special miracle is that the threads of the web are so finely spun that the construction of the fly's eye is too crude to perceive them, and the fly plunges without warning to its own destruction. In an analogous manner and completely without warning, we drink water that contains invisible cholera germs. The web is truly a refined work of art that the spider has painted of the fly.
But stop! That is not what the spider does at all. It weaves its web before it is ever confronted with an actual fly. The web, therefore, cannot represent the physical image of a fly, but rather it is a representation of the archetype of a fly, which does not exist in the physical world.
...
An original program exists both for the fly and the spider. And I would maintain that the fly's original program (or 'archetype') influences the original program of the spider in such a way that the spider's web can be called 'fly-like' (fliegenhaff).
Behind a curtain of natural events, the various programs or archetypes are linked by a comprehensive meaning-plan.
In individual instances, it is enough to trace out the articulation between specific meaning-utilizers and specific meaning-carriers so as to gain an insight into the web of the Umwelts (Umweltgewebe).
Jakob von Uexküll, "The Theory of Meaning," 1982
Anatomical features: one of the smallest Araneidae to be seen in Sicily, its body length is only 3 mm in males and 4.5 mm in females. A peculiarity of this spider is the pattern on the opisthosoma (rear part of the body) consisting of a white spot at the top, bordered by a black outline, two dark lateral spots in the centre and a dark terminal leaf pattern.
Behaviour: A diurnal spider, it builds a very dense orbicular web with 50 spokes, at the centre of which it stops to wait for prey.