Feeding your tarantula correctly is crucial to their long-term health. Some tarantulas seem to have an insatiable appetite, willingly eating anything you drop into their cage. Understandably this leads to some keepers asking if you can overfeed a tarantula.
Can tarantulas get obese, and if so will it shorten their lifespan or cause other health issues?
In reality, tarantulas are a lot smarter than that.
You cannot overfeed a tarantula, and they are unlikely to get overweight.
Instead, a tarantula that eats well is simply more likely to grow quickly, and a tarantula that has eaten enough food may simply refuse the next meal you offer.
In general, if your tarantula is hungry then feed it. That said, there are some important exclusions to be aware of, as the longer answer to this question is somewhat nuanced.
How Do I Know If My Tarantula Is Hungry?
Some – though not all – tarantulas will change their behavior when they’re hungry. More than likely they will become more visible as they wait patiently for a suitable prey item to pass within reach.
A burrowing tarantula that you haven’t seen in weeks may suddenly be seen sitting at the entrance to their burrow. An arboreal tarantula like a Poecilotheria regalis may also be seen resting uncharacteristically on their cork bark hide. These are often signs a tarantula is on the hunt.
However these signs can be quite subtle, and aren’t necessarily seen in all tarantulas. In reality very few of my tarantulas exhibit signs of “hunger” from one day to the next. Yet when offered food they will still greedily take the feeder insect down.
In truth, the only guaranteed way to tell if a tarantula is hungry is to offer it a suitably-sized prey item and see if it gets eaten. Anything else is largely a shot in the dark, particularly with smaller or shyer specimens.
How Often Should You Feed a Tarantula?
If the only way to tell that your tarantula is hungry is to offer it food, the next obvious question is then how often you should feed your spiders.
There are a lot of variables that can affect this question.
For example, some species grow slower than others, and therefore have comparatively small appetites. Other species may go off their food for weeks or even months at a time in response to environmental factors.
Juveniles attempting to get as large as possible as quickly as possible may eat far more frequently than a mature adult that is just in “maintenance” mode.
Putting this aside though, a good rule of thumb to start with is feeding your tarantulas once every 7 to 10 days.
A longer gap between feeding won’t necessarily cause your tarantula any health issues, but of course a lower food intake may result overall in slower growth.
What is Power Feeding in Tarantulas?
“Power feeding” is the name some hobbyists give the process of feeding tarantulas as much as they will consume, either in terms of frequency or volume.
To give a specific example I had a Poecilotheria regalis in the past that would eat daily if given the opportunity. I fed it at least one prey item every night for weeks on end until it decided it had had enough.
On a smaller scale, while I generally feed most of my tarantulas once every week or so – giving the odd week or two without food every so often – this isn’t the case with every specimen. Many spiderlings and juvenile tarantulas will eat twice a week if given the opportunity.
Feeding twice a week can have a number of benefits for the tarantula owner. Primarily they allow the spiderling to grow into a decent-sized specimen a lot quicker.
Additionally, this can be a handy tool for those keepers who buy “breeding pairs” of tarantulas from suppliers. These “pairs” tend to entail two tarantulas of near-identical size. Seeing as males tend to reach maturity earlier than females, this can lead to the frustrating situation of ending up with a mature male and an immature female.
Modifying feeding schedules can help your females to grow faster, hopefully permitting the two tarantulas to mature at around the same time.
Of course, rather than feeding females twice a week and males once a week, an alternative is to feed females once a week, and males once every two weeks. Or to keep feeding frequency the same, but to deliberately offer larger prey items to your female, and smaller feeders to your males. The end result is essentially the same.
Arguments Against Feeding Your Tarantula Too Much
As a concept, power feeding divides tarantula keepers. Many keepers want their pet to grow at a decent rate and worry about their tarantula getting hungry so feed quite regularly.
Other tarantula keepers, however, maintain that feeding your tarantula too often or too much is bad for their health.
In truth, I have yet to see any scientific evidence that feeding your tarantula more frequently negatively impacts their health. However there are a range of personal observations that some keepers swear by, no matter how lacking these proclamations are in evidence.
That is not to say that overfeeding a tarantula is necessarily good or bad – just be aware the evidence on either side of the divide is more a case of personal opinion than proven fact.
That said, in the interest of balance let’s discuss some of the main concerns shared by some keepers about power feeding tarantulas…
Heavy Abdomens = More Potential Damage
Terrestrial tarantulas are often thickset, and subsequently less “athletic” than arboreal species. Tarantulas like the Chile Rose Hair and Mexican Red Knee are perfect examples of such “chunkier” species.
The abdomen of an “overfed” Mexican Red Knee can reach truly impressive proportions, adding further to its weight.
It is believed by some keepers that this may increase the chances of your tarantula falling as it tries to climb up the sides of its cage. And if it falls, a heavy abdomen is more likely to split, leading to pain or even death.
This is one reason why many tarantula keepers prefer to keep such tarantulas in lower cages, or to add lots of substrate, so the tarantula is essentially unable to climb vertically.
Studies in rodents have shown that specimens fed less regularly tend to live longer. While I’m not aware of any such studies on tarantulas, naturally some keepers believe this same process applies equally in arachnids.
Without evidence, we can neither confirm nor deny this with any real certainty.
However, just be aware that some keepers believe that overfeeding a tarantula can result in it dying at a younger age than spiders fed less frequently.
Weaker or Infertile Mature Males
Some tarantula keepers blame breeding difficulties on males that have been overfed over an extended period of time. They believe that overfed male tarantulas may mature earlier – and at a smaller overall size. This may lead to difficulties with the mating process.
Furthermore, a few comments have been made about overfed males being infertile or generally being disinterested in mating with a mature female.
Once again, however, bear in mind these are the opinions and observations of a small subset of tarantula keepers and may not reflect the reality.
Greater Chance of Damage From Feeders
A more serious potential issue with power feeding is the potential damage to your tarantula from uneaten feeder insects.
Feeding your tarantula as much as it will eat greatly increases the chances of uneaten feeder insects remaining in the cage. Some uneaten feeder insects such as crickets are able to bite your tarantula so can cause annoyance. Worse, tarantulas can die during a molt when an unnoticed feeder insect nibbles on the helpless spider.
No matter how frequently you opt to feed your tarantula it is essential to remove any uneaten prey soon after feeding to avoid such situations. I also like to keep a simple feeding record for every tarantula in my collection so I can identify upcoming molts, and therefore stop offering prey at the right time.
Uneaten feeder insects may disturb a tarantula that isn’t hungry, causing unnecessary stress. You don’t want your tarantula getting scared out of its hide, for example.
In conclusion, here many issues are blamed on overfeeding tarantulas. After 25+ years of keeping tarantulas I have yet to see any real negative impacts from feeding tarantulas frequently, but then again maybe I’ve just been lucky so far. Or maybe a once-a-week feeding routine doesn’t count as frequent enough to count as “power feeding”.
Do Tarantulas Get Overweight?
Generally tarantulas do not get overweight. Instead they will eat until they’re full, then stop eating.
That said, many captive tarantulas are noticeably “fatter” than tarantulas observed in the wild. This is most commonly a problem in adult tarantulas.
Generally speaking a sling or juvenile that has eaten a lot will simply molt sooner, meaning a faster growth rate.
Why Is My Tarantula Eating So Much?
Tarantulas may willingly eat a lot for a variety of reasons.
Here are some of the more common reasons why some tarantulas have such a healthy appetite:
Fast Growth Rates
Some species of tarantula reach maturity much faster than others. These “fast growing” species naturally tend to eat more than slower-growing species. Eating more means they can become an adult that bit quicker than if they ate less frequently. Examples of fast growing species in my opinion include Poecilotheria regalis and Lasiodora parahybana.
Higher Ambient Temperatures
Being cold blooded, tarantulas tend to respond quite quickly to changes in environmental conditions. In terms of biology, higher temperatures allow chemical reactions in the body to happen quicker. This can include digestion, and subsequently growth.
Warmer temperatures, such as during the hottest months of the year – can have a noticeable impact on the appetite of your pet tarantula.
The reverse is also true, of course, and some tarantulas may go off their food entirely or at least eat far less during the cooler winter months.
Small Food Items
Your tarantula may be eating so much simply because it isn’t fully satisfied after each meal. Imagine if your main meal was just a meager portion. A single grape lets say. How soon after that would you be hungry again?
It may be that an always-hungry tarantula would benefit from larger prey items, or more of them in one sitting. In this way they can enjoy a real “feast” that will keep them going for much longer.
Larger Adult Size
Tarantulas pass through a similar number of molts between birth and maturity. This means that larger tarantula species need to consume much more prey between molts to reach these impressive evential dimensions.
Tarantulas that get big as adults – such as Goliath Birdeaters – therefore often have very large appetites.
Recovering From a Fast
A tarantula that has been refusing food for some time, yet has suddenly found their appetite again, will often try to make up for lost time. An example might be a tarantula that has been in premolt for weeks or even months. When it finally molts, and the exoskeleton hardens up, such a tarantula will often be ravenous. For a few weeks thereafter your tarantula may eat far more than usual to replenish their reserves.
Preparing to Produce Eggs
Lastly a mated female tarantula may well eat far more than normal as she builds up resources for egg production. Generally speaking feeding the spider a generous diet will result in a larger eggsac, and so more baby spiders to add to your collection.
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