Spiders are arthropods, and they breathe air. They have eight legs and their chelicerae with fangs, inject venom. Spiders are a well-known order of arachnids and found across all continents, except Antarctica. Spiders have their colonies across all habitats, except air and sea. There are over 48,000 species of spiders, but the debate still rages about their classification!
So, are spiders, insects, mammals or reptiles? Spiders are arachnids. They belong to the group called Araneae, They are not insects, mammals or reptiles. Everyone usually gets confused because the term arachnids is not known to everyone. Whenever we see some organism we usually like to throw them under these three categories however there are many other categories.
Spider’s body consists of two tagmata, cephalothorax and abdomen, joined together at cylindrical pedicel. This body structure is very different compared to all other insects. Spiders don’t have antennas. They have a central nervous system, unlike other insects. They don’t need external muscles on their legs since these extends thro’ hydraulic pressure as per requirement.
Their abdomen has a modified appendage called the spinnerets, which produces silk thro’ around six types of glands. Spiders of varying forms are in existence over millions of years. The method and type of web they weave vary with the species, and the quality of silk thread their spinnerets produced.
Bagheerakiplingi is the only form of a spider, which is an herbivore. All the other species are carnivores. Predators of spiders vary between insects, including spiders, lizards, and birds. They trap their prey in their web, using sticky bolas to engulf them or chasing them. They cannot digest solid particles. So they secrete an enzyme to liquefy their food before the same gets ingested. They also grind their food with their pedipalps, since arachnids don’t have mandibles for this function. Spiders identify their prey thro’ sense of vibration and even with the help of acute vision.
Males conduct various rituals before their courtship with larger female spiders. This helps them not to get eaten during and after mating. Females weave silk egg cases to store hundreds of eggs inside. Some spiders carry these cases with them, take care of them till they get hatched, and also feeds the young ones. Some varieties of spiders are social creatures, where they build colonies together, where nearly 50,000 spiders reside. They hunt their prey together and share the food which they have acquired. Usually, spiders live for around two years.
Venoms of few species of spiders are poisonous to humans. Researchers are working on the possibility of using spider venom in medicine. The quality of silk fiber produced by spiders was much more durable, elastic and light compared to synthetic yarns. Spiders’ silk genes are being widely used in mammals and plants to improve their silk-producing quality. The various behavior and traits of spiders are reflected in mythology, art, and scriptures down the ages in terms of their cruelty, patience, and creativity. Fear of spiders is known as arachnophobia.
Sense Organs
Eyes:Spiders have four pairs of eyes in the front end of cephalothorax. The front two eyes are capable of identifying images and focusing then in their retina. These eyes can move, compared to the other two, which are still and used to reflect light. The visual capacity of jumping spiders is many times more potent than most of the other insects.
Other senses: Spiders, in addition to the sense of sight, also are endowed with sense touch and smell. Depending upon the species, these senses get modified as per their requirement. For web-building spiders, all these other sensors are more important than sight, while for a hunting spider, vision is of paramount importance.
Locomotion
Spiders have elaborate legs with eight distinct parts. The coxa is the closest part attached to the cephalothorax. This coxa hinges with the rest of the elongated leg parts with a short trochanter. Next comes the long femur, which is attached to their knee cap patella. This gets connected to the tibia, and the foot or tarsus gets connected to tibia thro’ metatarsus. The tarsus ends with claws, made up of two or three points.
The entire leg gets activated thro’ hydraulic from cephalothorax. Hence, if this part of the spider gets effected, the legs of the spider become immobile. Some hunting spiders can jump up to fifty times their size, due to their developed hydraulic system. Hunting spiders have multiple tufts of fine hairs called scapulae. These are used effectively to walk across slippery glass or ceilings.
Silk Production
Spiders usually have three spinnerets, which emit silk. Each spinneret has multiple spigots, which has one silk gland at its end. The glands secrete a protein substance that hardens into tensile silk due to the process of being drawn out thro’ the spinnerets. This silk is primarily used to build the web to snare the insect who comes within proximity. The young ones use these silk to move up and down. While the female uses the silk to weave a case around its eggs for protection.
Reproduction And Life Cycle
Female spiders reproduce sexually, and fertilization is internal but indirect. Males spin a web and insert its sperm during copulation. This encased sperm travels through a syringe-like structure called palpal bulbs into the openings in the underside of the female’s abdomen. Males decides to impregnate a female, who are of the same species and are ready to reproduce, thro’ the sense of smell.
Spider’s courtship and mating is a ritual, which is not common among other insects. Females lay around 3,000 eggs in a silken sac. The eggs undergo the various larvae stage inside and hatch as young spiderlings. These young spiders can travel long distance thro’ using the smooth thread, called ballooning.
Size
Smallest species of spiders are as little as 0.35mm while the gigantic spiders are 90mm with their leg spans to about 250mm.
Coloration
There are three classes of pigments found in spiders – ommochromes, bilins, and guanine. Melanins, carotenoids, and pterins are absent in spiders, which are generally present in all animals. The pigments in the spider lead to brown, white, green coloration. Fine hairs and scales reflect light to bring out the silvery appearance.
Some Important Facts
- Though spiders are poisonous, they are not very harmful to humans, except for a few species.
- Some spiders are herbivores, including feeding on pollen and honey.
- When spiders walk, only four legs touch the ground.
- Spiders have blue blood.
- Spider’s muscles can pull in their legs, but a water pump is required to pull out its legs.
- The most deadly spider in the world includes the black widow, funnel web, and brown recluse spiders. The black widow spider’s bite can lead to nerve-related ailments in humans.
- The most poisonous spider in the world today is the Brazilian wandering spider, which lives on the forest floor. Their venom is fatal to humans.
- Spiders have muscles inside their exoskeleton.
- Different spiders can move on different surfaces since their legs are made that way. Some can walk on a slippery surface, while others can crawl on your home ceiling. Those with claws require a hard surface to move.
- Spiders have inspired robots to be made for spacecraft repairs to get undertaken.
- Spider created silk is five times stronger than steel of similar thickness. If you gather their webs as thick as a pencil, you could stop an aircraft in flight. Researchers haven’t been able to replicate their silk, artificially, yet!
- Hummingbirds use sticks and silk from the web to weave their nest.
- Most spiders build their web every day.
- Some males present females with dead flies as gifts.
- In the early days, spider web placed on wounds as dressing helped in healing. Now we know that the silk contains vitamin k.
- A female black widow requires to mate only once. She would continue to lay eggs during her lifetime of two years.
- Spiders have six to eight eyes and are nearsighted. The tiny hairs on their legs are used to smell and feel.
- Many spiders have a string of silk attached to them like rock climbers. They use this to escape from any threat quickly.
- Most female spiders are more significant than their male counterparts.
- A web is sticky since the spiders release droplets of glue-like substances. This gives the web elasticity.
- Spiders don’t feed on human blood, nor are they interested in attacking humans. They bite in the form of attacking with their fang and venom, only if they feel threatened.
- Some spiders eat their web and use the amino acid to produce a new web.
- On average, there are 130 spiders per square meter.
- Some species of spiders can see the light in the UVA and UVB spectrum, which is not visible to the human.
- Most spiders are solitary animals and only be seen together during mating.
- Spiders use indigenous ways to trap their prey.
- They constitute an essential food source for birds, fish, and mammals.
- All spiders spin silk, but all don’t spin a web.
- Cob-webs are abandoned webs by the spider, who weaves new web every day.
- Most spiders are nocturnal since they can’t see well. They feel through vibrations and the fine hair on their legs.
- Most spiders have water-repellant hairs, which helps them from drowning for a short while.
- The enormous spider is the goliath tarantula, which can prey on birds.
- Spiders don’t have compound eyes. All their eyes are simple.
Are Spiders Insects
Technically, spiders are not insects. The reason is as follows:
Taxonomy: As per the classification of all living things, spiders, insects, birds, fish, and humans are all part of the animal kingdom. Here animals breathe, move, and are multi-cellular.
Arthropod: Insects and spiders are both arthropods. These are invertebrates, i.e., the lack of a spinal column. On the outside, they have a hard exoskeleton, which gets made of chitin. To grow, arthropods need to shed its old, hard outer skin. Spiders molt or shed their hard skin ten times during its lifetime. Another critical aspect of arthropods is that they have segmented legs like in spider.
Arachnids: Spiders are arachnids like scorpions, mites, and ticks. However, the difference is that spiders have eight legs, while others have six. Next, insects have bodies, which are in three parts, while spiders only have two. Insects can all fly to some extent, while spiders cannot fly at all. Finally, most insects are herbivores, while spiders are a carnivore.
Are Spiders Mammals
Spiders belong to the family of arachnids, along with scorpions and mites. Arachnids belong to the family of arthropods, which also includes crustaceans like lobsters and shrimps. Spiders have a very thin waist, separated by the pedicel. They get classified into a separate group called the Araneae. This distinguishes them from other animals in this family.
Some species of female spider secretes a milk-like substance at the time of hatching of eggs, and it got observed that the young ones feed on these droplets. They are also seen congregating around the abdomen of the female for feeding on this milk-like secretion. It got tested that this secretion is rich in protein, four times more than cow’s milk!
These female species also show maternal care for their young ones, by caring and feeding them. They are also found to be social living, hunting, and eating together. However, these traits are seen in some species of cockroaches and birds too!
Are Spiders Reptiles
There are some varieties of spiders that live near water, like the diving bell spider or water spider. This variety lives underwater. This variety falls under Argyoneta Aquatica. There are some other varieties of spider which dives inside water for food. The water spiders live in freshwater.
Though these spiders to breathe air, they trap their required quantum of air in its abdomen. They prey on aquatic insects and crustaceans. But their similarities with other reptiles and amphibians end there.
Conclusion
Spiders are not an insect, or a mammal nor a reptile. They belong to a separate group called the Araneae. They exhibit characteristics of each of these animal species but don’t belong to either of them. They existed in nature for millions of years and are an essential element to our ecosystem.
Welcome to my blog. I have been doing pest control for years since my house, garden and pets were always attacked by various kinds of pests and as a result I had to know proper pest control techniques that works. In this blog I share all the tips and tricks that I know and I hope you’ll find it helpful.