The diet of spiders varies from one species to another.
For example, weaving spiders prefer to feed on some types of insects such as flies, mosquitoes, and moths, while hunting spiders attack larger insects such as locusts, beetles, and cockroaches, and some giant hunter spiders such as spider Huntsman from hunting lizards and frogs, and some spiders are famous for their preference for a certain type of food, such as the white-tailed Lampona spider, which prefers to eat other spiders and rarely looks for another type of food.
Some types of spiders adopt innovative ways to obtain their food, for example, the Kerengga spider convincingly fakes its shape to become similar to the form of ants and lives among them, and takes the appropriate opportunity to devour what it can of them, while the magnificent spider (magnificent spider) known scientifically as Ordgarius magnificus uses another method , where he suspends a liquid drop containing a pheromone that attracts insects such as ants and mites to the drop, and devours them when they approach him, and it is worth noting that spiders prefer to eat their prey alive, but they can eat dead prey only a short time ago.
Spiders do not usually eat plants because their digestive systems cannot digest cellulose, and they cannot eat solid food, however, a recently discovered Central American spider known as Bagheera kiplingi (” Bagheera kiplingi “) that lives on the acacia tree and feeds on nectar, has the capacity to digest sugar, proteins, and fats.
Spiders usually derive water from the prey they feed on, and from the water that is produced as a by-product of the metabolism processes in their bodies, so they do not need to drink water, however some types of spiders need a high level of moisture to be able to live, otherwise they will be exposed to dehydration, and some of these spiders include some Tarantula spiders spend most of their lives inside moist burrows. Males come out only at night when the humidity is high, or during the day during the rainy season.
Funnel-web spiders, which love moisture, spend their time near swimming pools or garden taps. Water is leaking out.
Spiders spread in all types of habitats except for the polar regions, high mountains, and oceans, and some types of spiders are able to live in rocks and coral crevices that are found in tidal areas on the edges of the oceans, and the distribution of spiders depends on many factors, including: geological processes that led to the separation of the continent The ancient giant spiders over millions of years to form the now-known continents, and the separation of the continents led to the separation of some spiders from the rest of their species, as they evolved independently to produce a new type of spider.
Some types of small spiders, and small spiders, are able to move from their original environment to new environments that are long distances from them, and they are related to their silk threads that are picked up by the wind and transported across land and sea.
Orbital spinner, and wolf spider.
Some phenomena such as climate change and sea level rise lead to the isolation of some spiders in areas known as their refuge habitats – such as caves, mountain tops, and islands – and they are unable to return to their natural environment, and over time some of these spiders are exposed to a series of random genetic changes and mutations Which leads to the production of new species that can adapt to new conditions.
Reproduction in spiders
The reproductive process of spiders is summarized in three stages:
The stage of searching for a female spider
Spiders are generally spread over large areas, which makes it difficult for males to find a mature female ready to mate, and in most species, the female facilitates the task of the male and announces her readiness to mate by secreting special pheromones, and when the male smells the pheromone with the chemical sensors that are located on his front legs It follows the smell to reach the female, and females can excrete pheromone directly in the air, or encapsulate the networks that they build, and sometimes males resort to watching immature females during their development stages and mate with them immediately after the end of the last moulting stage.
After finding the female, the male is keen to get rid of the competitors, so the males of the species whose females spin a net coated with pheromones resort to destroying the network so that the other males do not pick up the signal, and then he devote himself to another task which is to convince the female that he is not a predator, nor food, but a male belongs For the species to which she belongs, and that he is willing to mate with her, and therefore begins to flirt with her, and the methods of courtship differ from one type to another, for example, the male spiders flirting with the female’s web by shaking a thread connected to the web in a distinctive way, while the males of the wolf spider and jumping spiders flirt with the female by dancing .
When male spiders sexually mature, they ejaculate semen onto a web they build called the spermatic web, then the tentacles – which are appendages located in the front part of the body – absorb the sperm from the web, and they swell due to the pressure of the fluid, and when mating, the male transfers the sperm from one of the tentacles to the female in The tentacle size is back to normal, except for the fishing spider where the tentacles remain swollen, the male shrinks and hangs from the female’s body and dies within a few hours, and in spiders that are four times the size of the female, the male’s legs flex immediately after mating.
He is attached to the female without movement, his heart stops beating, and he dies.
egg preservation stage
After mating, female spiders weave a solid egg sack in which to lay eggs ranging from one to several hundred depending on the type of spider, then fertilize the eggs from the sperm that she has stored inside her body, and after several weeks the eggs hatch and the young spiders come out, while the females of some types of spiders leave a bag The eggs are in a safe place and go.
The females of many species of spiders guard the eggs from predators until they hatch. An example of this is the female wolf spider who carries the egg sac with her, and when the little spiders are ready she bites the egg sac and comes out and remains hanging on the mother’s back for ten days.
Respiration in spiders
Spiders breathe through an open respiratory system, which contains the heart, which pumps hemolymph (blood and lymph) instead of blood through the arteries to the sinuses that surround the internal organs of spiders. The body through openings on the lower surface of the abdomen, and from there oxygen diffuses to the book lungs filled with hemolymph, and in some types of spiders, the back book lung is partially or completely transformed into a windpipe to which air enters through a pair of openings located on the chest or on the abdomen, or through Through one opening near the spindles, it spreads to the hemolymph or to tissues and organs directly, while the anterior book lung remains the same, and in smaller species of spiders, the book lungs are reduced or disappear completely and are replaced by the bronchi, and very small spiders that live in moist environments breathe. During the exchange of air across the surface of the body, it is worth noting that breathing through the bronchi secures the exchange of oxygen more effectively despite the volume of The heart of the small, and enables spiders to live in very dry environments.
The mechanism of movement when spiders
The synergy between the legs and the hydrostatic pressure from the heart pumping hemolymph enables the spider to move, while the muscles help to fold it inwards; by this simple mechanism the spiders can move in a number of ways.
Spiders walk by keeping one pair of legs on the ground to support them, lifting the other pair into the air, and then returning the ball, but this time alternating the pairs of legs that keep them on the ground and those that lift them up in the air, and spiders can walk on horizontal and vertical surfaces even relatively smooth ones thanks to hair The flour that covers her legs.
Spiders can run at a speed of 53 meters / sec, which is a very large speed when compared to the length of the body, and some spiders are able to jump a distance of up to 25 times their body length, thanks to the sudden change in blood pressure (hemolymph) that occurs due to muscle contraction. Which connects the plates of the head and chest, which reduces the volume of blood in this area, which causes a rush of blood to the eight legs of the spider and forces it to expand quickly, so the spider rises in the air.
Fish-eating spiders or rafts are able to float on the surface of the water thanks to their ability to distribute their body on the water, due to their light weight that does not exceed 1.7 grams, and their legs covered with thick hair, and after they float on the surface of the water it becomes easy for them to use the second and third pair of spiders.
Its legs are for paddling and swimming in the water.
Spider web building mechanism
The spider begins building the web by producing a thread of silk and fixing it on a suitable fulcrum such as a tree branch or something else, and leaving its other end free to be carried by the wind to another fulcrum. The silk is fixed on both ends of the bridge so that it hangs down in the form of a letter V, then another thread of silk is spun down to become a Y-shaped net.
After that, you start spinning several circular threads from the center of the net towards the ends, and then you start spinning spiral threads that extend from the center of the net towards the ends.
After the shape of the net is completed, the spider begins to produce silk threads mixed with a sticky adhesive, and it begins to eat the spiral threads that you have fixed as a reference, and replace them with sticky silk threads, and thus the web becomes composed of non-stick circular threads so that the spider can walk on it, and sticky spiral threads To catch insects, and after the spider has finished its mission, it lies in the center of the net to be able to pick up the vibrations that indicate the fall of prey in its web.
The delicate silkiness during the spinning process thanks to the serrated claws that are located on the tips of its legs.
Hunting with spiders
The methods of spiders catching prey differ from one species to another.
The Bolas spiders resort to forming a ball of sticky silk and attaching it to a thread after saturating it with a chemical that smells similar to the smell of female moths, thus creating a natural trap for male moths that are attracted to the smell.
Pirate spiders use an innovative method to trap other spiders.
They start shaking their nets in a similar way to what happens when an insect gets stuck in the nets, and lies waiting for the spider that comes to devour its prey, only to find itself becoming prey to another spider, some spiders such as African funnel web spiders (The African funnel-web spider) work collectively to hunt their prey, where hundreds and even thousands of spiders live on a single web, which is contrary to what is known about spiders as solitary animals, while spiders of the genus Scytodes catch hunt by spitting a sticky substance or glue on the prey. Lynx spiders that live on trees have adapted to their environment thanks to their agility, which enables them to jump from one trunk to another easily while chasing prey.
Ground hunter spiders are able to catch large and dangerous prey, thanks to their ability to release sticky silk on the prey’s mouth and legs to paralyze its movement before attacking it. Ground spiders are distinguished by the fact that their silk-producing glands are larger than those of other spiders, and they are less invasive. The silk mixed with the glue it produces is less viscous than other silk, yet it is strong and durable, and can withstand 750 times more pressure than industrial glue can withstand.
Trapdoor spiders use a different method to catch prey, they dig holes and cover them with a cover tied with spider silk and lie waiting for their prey, and some spiders hide inside flowers waiting for insects, and jumping spiders are able to hunt their prey efficiently and effectively thanks to their large eyes Which helps it detect the presence of prey even if it is far from it, and also for its ability to jump on prey at the right time a distance that exceeds its body length by 50 times – although the muscles of its legs are not particularly strong – and this is due to its use of hydraulic pressure, as it squeezes a special muscle in Prosoma (head – thorax) body fluids to the legs to expand them.
Elimination of prey
After spiders catch their prey, they use hooks, a pair of articulated jaws located in front of the mouth to kill and devour the prey. Each jaw consists of a basal part inside which is a sharp claw, which in turn consists of a hollow duct that ends with a small opening.
The claw transfers venom from the poisonous gland through the duct to the body of the prey to paralyze it.
Or kill it so that the spider can eat it without having a chance to resist.
The hook works differently from one species to another. In tarantulas, for example, the claw is used, like an ax, to inject venom into prey, while Araneomorphae spiders aim the two hooks at each other like pincers, then twist to facilitate paralyzed spiders with prey.
Move it to the nest, and sometimes spiders wrap prey with silk threads even before injecting it with venom to make it easier to attack.
Spiders need to liquefy the prey before they can devour it, so they secrete digestive enzymes on it, and some spiders resort to injecting the prey with the digestive material directly, which leads to the liquefaction of the internal parts of the prey and the survival of the external skeleton somewhat intact, then absorbing the liquid material after filtering it through the hair Hooks and mouth, and some types of spiders chew their prey first using serrated appendages found on the hooks, then secrete the digestive fluid on them and start absorbing the tissues of the prey that have turned into a liquid.
digestion of prey
The process of digesting the spider’s prey somewhat begins as soon as the venom is pumped into it, because the venom contains digestive enzymes, while the real digestion begins when the spider injects the prey with hydrolase enzymes that dissolve or liquefy the tissues of the prey, then the spider absorbs the liquid tissue into its intestines, then re-pumps it A second time with more enzymes to the body of the prey, and then re-absorbed, and this process aims to mix and distribute the digestive enzymes and distribute them better, which leads to the destruction of the prey tissues completely, and examples of enzymes hydrolase, protease enzymes, lipase, nuclease, and carbohydrase, These enzymes are able to function without the presence of specialized proteins of the endopeptidase family that break down the intercellular tissue that protects the cells and tissues of prey from being attacked by hydrolase. These proteins include elastase, hyaluronidase, and collagenase.
These proteins also cut the prey proteins into smaller pieces They can be transported to the spider’s gut, where other proteins called exopeptidases break down the peptides by breaking the bonds between amino acids.
After that, the last part of digestion begins, where the various nutrients are transferred inside the cells of the spider’s intestines by the method of cellular drinking or absorption of cellular fluids (pinocytosis), and there these elements are subjected to further destruction.
All spiders resort to biting to protect themselves, especially if they are unable to escape, and some types of tarantulas use another type of defense, which are ultra-fine bristles that cause irritation and sometimes allergic reactions to the attacker, and the golden wheel spider (Carparachne aureoflava) uses a specialized defensive tactic, where it can Escape from the tarantula hunter wasp by turning its body to the side and rolling like a wheel, and it is worth noting that if the wasp manages to catch the spider, it will lay its eggs in its body so that its larvae feed on cobwebs when they hatch.
Web-spinning spiders, scientifically known as N. antipodiana, are able to spread chemicals on the silk threads to deter the workers of ants, which belong to the family Pamela that usually attack spiders, and these chemicals include hypyrrolidone-2, and the alkaloid pyrrolidine, and spiders use as a defense method. It was attacked, and its toxins, which target the muscles and nervous system, paralyze the attacker, and raise the level of sugar in the blood, which leads to damage to body functions.
adapting to the environment
Adaptation for hunting
The methods of hunting spiders for their prey differ from one species to another depending on the environment in which they live, and the type of prey they feed on, as most spiders use nets to catch their prey, while some species choose to hide among plant parts and wait for the prey to approach them to pounce on them and surprise them, while some have adapted Spiders dive underwater to reach their favorite prey despite the fear of other spiders from water, and similarly other spiders adopt various behavioral adaptations to suit the environment in which they live.
Some types of spiders that live in an environment that usually suffers from a scarcity of prey, show a behavioral adaptation in the event that they find a large number of prey, as they deliberately kill prey that exceeds their need, and eat them until they are full, and leave the rest of the prey half consumed or completely intact, and it is worth mentioning This behavior is strange to spiders that live in an environment where food sources are available, as they rarely leave the remains of their prey.
Araneoid sheet web weavers build complex three-dimensional webs, which is a type of adaptation that enables them to catch prey more efficiently, which means increasing their chances of survival and increasing their numbers.
To repel the attacks of mud wasps, it also allows spiders to diversify the forms of webs that they make.
An article published in the “Journal of Animal Ecology” notes that tropical spiders exhibit special adaptations depending on the altitude at which they live, with lowland spiders being social while high-altitude spiders are semi-social. They live in low areas and are large, which means that only social spiders are able to cooperate to hunt them.
Some animals, when exposed to danger, resort to a behavioral adaptation known as autotomy, in which the animal separates part of its body, and a famous example of self-excision is what a lizard does when a predator catches its tail, so it rushes to separate it from its body and flees, spiders also practice the same trick. It gets rid of its leg when it gets stuck somewhere and can’t release it, which is what happens when the leg gets caught in a spider web, or gets trapped in the mouthparts, or when it gets injured.