How long can spiders live without food and water?

Spiders certainly don’t look like animals with voracious appetite. Most of them are skinny and look very satisfied with their tiny diet of pus-filled flies and bugs. But then there are bigger species of spiders that prey on animals as large as house mouse and fish, so their appetite isn’t really as small as we’d thought in the first place.

When it comes to food and water scarcity, every animal has one or two ways of dealing with this problem. Some like the ground squirrels save up enough fruits and nuts against the onset of the barren months, while others like lemurs and bats hibernate their time out until the productive periods appear again.

As for spiders, they fast their way out of the difficult situation similar to the adaptation that some polar bears employ during the arid atmosphere of the summer months.

In this article, we are going to be looking at this fasting behaviour in a more in-depth manner. We’ll see how long spiders are able to endure without eating food or drinking water.

How long can spiders live without food?

Some species of spiders can survive several months on end without food while others can barely survive a week. A few species have been observed to fast for longer than 200 to 300 days and even more. When presented with the opportunity to eat however, spiders will not hesitate to trade their fasting for sustenance.

How can spiders live without food?

Spiders are able to survive exceptionally long periods of food scarcity all thanks to some four impressive characteristics that they posses.

  1. A low resting metabolic rate
  2. Ability to further lower their metabolic rate.
  3. Efficient energy management.
  4. Selecting a highly nutritious menu.

1) Low resting metabolic rate

Spiders have a low resting metabolic rate in comparison to other animals. In fact, they have 30% less the resting metabolic rate expected of ectothermic arthropods their size.

In case you’re wondering what resting metabolic rate means, it’s the total amount of calories burnt by the body when completely at rest.

Having a low resting metabolic rate naturally means that the body burns significantly less calories when supporting resting activities like breathing, circulation of blood (or hemolymph in the case of spiders), organ functions and basic neurological functions, than it does when the percentage is high.  

For spiders, having just 70% of the resting metabolic rate expected of arthropods their size means that they naturally expend fewer amount of energy at a much lesser cost than other arthropods.

This natural advantage in energy expenditure helps boosts their fasting potential by a great degree.  

2) Ability to reduce their metabolic rate

Aside from the fact that spiders have a naturally low resting metabolic rate, implying that they expend very little amount of energy at any given time, they also have the ability to thump down this metabolic rate at will, by about 16 percent or so when the need arises, for example, during periods when food resources become scarce. They are also able to increase their metabolic rate when the need arises, to about 6 to 7 percent of the original value.

This incredible feat means that spiders will be able to reduce their energy expenditure to a value even more than their current expense, which would make an extended fasting feat even more possible.

Spiders, during periods of food scarcity (a sole characteristics of their lifestyle), often drop their metabolic rate gradually and at a steady pace, by about 16 percent, over the course of one to two weeks. Then, they maintain this rate and begin to rely more on other adaptations to limit their energy expenditure.

3) Efficient energy management

Spiders are masters of energy management, and it’s written all over their anatomy, physiology and behaviors. Almost everything about them from locomotion, respiration to hemolymph circulation, is designed to be energy efficient.

To get the idea of what we are talking about, lets take a look at the spider’s locomotion and posture as an example.

Spiders are able to use very small amount of muscles on their legs for locomotion and when maintaining a constant posture, they use only a small percentage too.

For the first case, when extending their legs, for locomotion, spiders use hydrostatic pressure (or their body fluid) instead of solely relying on muscles and when achieving a stagnant posture, they maintain a constant hydrostatic pressure instead of using the musculature on their legs.

These means of avoiding muscle usage, helps them conserve a lot of energy since muscles require a lot of energy to be maintained. One effective way that spiders also avoid overworking the little muscles they put into action during locomotion is by their constant posture.

Most spiders are generally sit and wait predators, so they are happy to sit all day and wait for potential preys to fall into their silk traps. This way, they are able to kill two birds with one stone, the first bird is an extra energy expenditure and second is finding nutritious prey free of charge.

Another example to shed light on this matter of energy conservation is their respiratory system. Spiders have a book lung respiratory system, a kind of system that resembles a folded book, which is extremely efficient at exchanging gas with the surroundings.

The unfolds of the book are filled with hemolymph (the spiders blood like fluid) and the folds of the book basically maximize the surface area exposed to air, there by maximizing the amount of gas exchanged with the environment.

All these traits and characteristics enable spiders to be able to conserve the little energy they have so that it may last them for longer durations.

3) Spiders are selective when it comes to food

Having all these peculiarities would of course be a very big waste without having the right source of nutrition, and so spiders have made it an essential to become choosy when selecting menu.

They tend to go for insects with higher nutritional contents and abandon those that look dry. This enables them to stock themselves with so much energy that would last then for however long they desire to fast.

When do spiders fast?

All spiders fast for two occasions:

  1. When faced with limited food resources
  2. When ballooning, which still leads back to the first point of food scarcity.

1) When faced with limited food resources

Generally, spiders as a whole are hypothesized to be food limited in nature, and one cannot help but agree with this hypothesis, i mean, when last did you see the spider living at the corner in your room catch food on its web?

Anyways, all spiders fast when they are hunger stricken and depending on species and age, can fast for periods ranging from a few weeks to about one year.

Often smaller spiders, having smaller energy budget, are able to fast for longer durations than bigger spiders, and adults are suited for longer fasting than spiderlings of the same species.

2) When ballooning

Ballooning in spiders is basically a means of invading new territories. Many spiders, often the light weight ones, extrude pieces of silk form their abdominal region and use it to fly or balloon to new territories in jet stream air.

Whilst on this journey, spiders can fast for as long as the journey extends and without drinking water. Some journeys can last for 25 days on a stretch, and the travelers are known to survive without food and water. This ballooning is the only period when spiders willingly agree to fast.

Do spiders loose weight after fasting?

Yes, spiders can loose up to 1/4 the their total body weight after a relatively long period of fasting. Equally, they can gain close to or even more than this amount when fed consistently in the lab or at home with nutrient rich insects.

Some spiders (especially the smaller species) can die due to starvation, after their fasting threshold is exceeded and food or water is far within reach.

How long can spiders live without water?

Spiders apparently can endure several months without food, but they can’t without water. Almost all spiders need to drink water at least once or twice per month to keep body hydrated and organs functional.

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Cite this Article (APA Format)

Bunu. M. (2020, May 15). How long can spiders live without food and water?. Retrieved from

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