Black Widow spider
Purpose
2
Observation Female widow spider’s purpose is to protect the egg sacs from external bodies. They spin the web during the day time. To catch the prey on their web. To feel the sound vibrations and prey as their eyesight is poor.
Analysis They is aggressive when they are protecting their egg sacs or when they are disturbed. They can live for 90 days without consuming any food. They spin irregular web with the sticky silk, it is as strong as it could hold a mice.
Inferences Nocturnal Their venom has the potential ingredient in medicine which may help the heart attack victims by enhancing blood flow.
Structure Observation The brains , jaws, eyes, stomach and leg attachments are on the upper smaller region. The lower big region contains heart, guts, silk glands and the reproductive parts. They have 8 legs with 7 segments on each leg. The ventral side (bottom) has an hourglass shaped red mark.
Analysis The segments on the leg facilitates movement. The legs taper towards the end so that less surface area is in contact with the sticky web. The web of the black widow is irregular in shape. Constructed of rough silk, it appears disorganized but is actually carefully planned. Black widow spider webs contain three deliberate structural levels: an uppermost labyrinth of sustaining threads, a central area of twisted threads and a lower level of vertical trap weaves. These arachnids are surprisingly clumsy when not in direct contact with the web. When attacked, black widows drop from their webs to feign death.
Inferences Leg attachments on the front balances the weight of the spider. The spider rests on 8 points ! The weight is distributed evenly as the
3
Geometry Observation The spider is bilaterally symmetrical in nature. The female is 30 times heavier than male. The tensile strength of spider silk is comparable to that of steel wire of the same thickness. However, as the density of steel is about six times that of silk, silk is correspondingly stronger than steel wire of the same weight. 8 legs are attached perfectly at angles on the ventral abdomen for locomotion. Position when the spider mates.
Analysis The formation of triangles within the web increases the strength of this web than other cob webs. Geometry of the structure play a great role in the spiders actions. The spider generally hangs upside down
Inferences Weight distribution of the entire body on 8 tips/points of the legs.
4
Growth
5
Mating : The animals most at risk from the black widow's bite are insects—and male black widow spiders. Females sometimes kill and eat their counterparts after mating in a macabre behavior that gave the insect its name. Black widows are solitary year-round except during this violent mating ritual.
Spiders reproduce sexually and fertilization is internal but indirect, in other words the sperm is not inserted into the female's body by the male's genitals but by an intermediate stage. Male spiders do not produce ready-made spermatophores (packages of sperm) but spin small sperm webs on to which they ejaculate and then transfer the sperm to syringe like structures on the tips of their pedipalps . When a male detects signs of a female nearby he checks whether she is of the same species and whether she is ready to mate; for example in species that produce webs or "safety ropes", the male can identify the species and sex of these objects by "smell".
Black Widow Spiders life span stages
Transition 6 Most spiders that hunt actively, rather than relying on webs, have dense tufts of fine hairs between the paired claws at the tips of their legs. These tufts, known as scapulae, consist of bristles whose ends are split into as many as 1,000 branches, and enable spiders with scopulae to walk up vertical glass and upside down on ceilings. It appears that scopulae get their grip from contact with extremely thin layers of water on surfaces These spiders spin large webs in which females suspend a cocoon with hundreds of eggs. Spiderlings disperse soon after they leave their eggs, but the web remains. Black widow spiders also use their webs to ensnare their prey, which consists of flies, mosquitoes, grasshoppers, beetles, and caterpillars. Black widows are comb-footed spiders, which means they have bristles on their hind legs that they use to cover their prey with silk once it has been trapped. To feed, black widows puncture their insect prey with their fangs and administer digestive enzymes to the corpses. By using these enzymes, and their gnashing fangs, the spiders liquefy their prey's bodies and suck up the resulting fluid.
Inter relationship between parts
Male
Female Life
Life 4 months
1 year Predator venomous
Weight 1 gm
Weight 30gms
Size 3mm to 5mm
7
Size 5mm to 13.5mm
1 Chelicera 2 Venom gland 3 Brain 4 Pumping stomach 5 Forward aorta branch 6 Digestive cecum 7 Heart 8 Midgut 9 Malphigian tubules 10 Cloacal chamber 11 Rear aorta 12 Spinneret 13 Silk gland 14 Trachea 15 Ovary (female) 16 Book lung 17 Nerve cord 18 Legs 19 Pedipalp
Proportions Observation
Male and female weight ratio is 1 : 30 Legs are longer for the entire body to spread out in order to distribute weight . Head is very small compared to the body. The spiders have secondary and primary eyes.
8
Colour Observation Not all adult female black widows exhibit the red hourglass on the ventrum or underside of the abdomen — some may have a pair of red spots or have no marking at all. Female black widows often exhibit various red markings on the dorsal or top side of the abdomen, commonly two red spots. Black widow young have at least some sort of marking on their abdomens. Adult male black widows are a quarter the size of the female, and are usually gray or brown rather than black and red; while they may sometimes have an hourglass marking on their ventral abdomen, it is usually yellow or white, not red Red colour is to warn the enemeis .
Inference Red colour spot signifies danger. Nature warns and attacks only if disturbed !
9
Texture An important characteristic of the black widow spider is its comb foot. This row of 10 strong, curved bristles is located upon the hind pair of legs and is used to pitch silk over captured prey Analysis • Spider bite causes swelling, redness, cramps, increasing heart beat etc • Hair gives them great grip on the fine web Inferences • Web-spinning also caused the association of the spider with creation myths as they seem to have the ability to produce their own worlds.