Tarantulas are obligate carnivores, meaning animal-based prey is not just a preference but a biological necessity. They cannot digest plant material, they do not supplement their diet with fruits or vegetation, and every calorie they consume comes from other living creatures. But calling them simply carnivores undersells how specialised and fascinating their feeding biology actually is. The way tarantulas hunt, subdue, and digest prey is unlike almost anything else in the animal kingdom, and understanding it changes how you look at these animals entirely.
What Tarantulas Actually Eat
In the wild, the vast majority of a tarantula’s diet consists of invertebrates, primarily insects. Crickets, grasshoppers, beetles, moths, cockroaches, millipedes, and other arthropods make up the bulk of what most species encounter and consume on a regular basis. Smaller tarantulas and slings eat correspondingly smaller prey, from fruit flies and small crickets to appropriately sized mealworm larvae.
Larger species expand their prey range considerably. The Goliath Birdeater, Theraphosa blondi, one of the largest spiders on Earth by mass, has been documented eating earthworms, frogs, small lizards, and rodents in its South American rainforest habitat. As covered by Britannica, it even occasionally takes small birds, though this is opportunistic rather than typical. Other large tropical genera such as Lasiodora, Pamphobeteus, and Phormictopus are similarly capable of taking vertebrate prey when the opportunity presents itself. Despite the dramatic reputation, however, insects and invertebrates make up the overwhelming majority of what even the largest species eat on a day-to-day basis. Vertebrate prey is occasional and situational, not a dietary staple. Our articles on can tarantulas eat mice and can tarantulas eat earthworms explore both of those specific prey categories in detail.
How Tarantulas Hunt
Tarantulas are primarily ambush predators rather than active pursuit hunters. Most species, particularly terrestrial and fossorial ones, select a position near their burrow entrance or within a webbed retreat and wait for prey to come within range. The silk trip lines many species lay down around their territory serve as an early warning system, transmitting the vibrations of approaching prey directly to the spider through the ground. When something triggers those lines, or when the tarantula’s trichobothria detect the airflow disturbance of a nearby insect, the strike is explosive and precise.
The strike itself is delivered through the chelicerae, the fang-bearing appendages at the front of the spider’s head. Tarantula fangs work in a downward stabbing motion, unlike most other spiders whose fangs work laterally. Once the prey is seized, venom is injected to immobilise it. The venom of most tarantulas acts on the nervous system of invertebrates and small vertebrates, rapidly preventing escape. For a keeper watching their tarantula take a cricket, the whole sequence from detecting movement to subduing prey can happen in a fraction of a second. Our article on can tarantulas be trained has more on the sensory systems that make this level of precision possible.
The Digestion Process: Eating From the Outside In
Here is where tarantula feeding biology becomes genuinely extraordinary. Unlike vertebrates that chew food and digest it internally, tarantulas practice what scientists call extra-oral digestion, meaning the digestive process happens outside the body before any food is ingested. Research published in scientific literature and covered by Nature has characterised this process in detail.
After the prey is immobilised, the tarantula regurgitates digestive fluid from its midgut directly onto and into the carcass. This fluid contains a cocktail of hydrolases, including proteases that break down proteins, lipases that break down fats, and carbohydrases that break down complex carbohydrates. The spider then uses its chelicerae to work this fluid into the prey body, pumping it back and forth in a process sometimes described as refluxing, using the prey’s own body cavity as a kind of external stomach. Over time, the internal tissues of the prey are fully liquefied, and the spider sucks up the resulting nutrient-rich fluid through its fangs. What remains is a dry bolus of indigestible material, primarily the exoskeleton or skin, which the spider discards.
This method of feeding means tarantulas can consume prey considerably larger than what could fit through any internal digestive tract. It also means they extract nutrition with remarkable efficiency, since the digestive enzymes work on the prey’s tissues directly and the spider only ingests material that has already been broken down. The sucking stomach, a muscular internal organ that contracts rhythmically to draw in liquified prey, functions like a biological pump and can expand substantially to accommodate a large meal. A well-fed tarantula will often show a visibly enlarged, rounded abdomen for days after eating.
Tarantulas Cannot Eat Plants
This point is worth being explicit about because the question occasionally comes up. Tarantulas lack the enzymatic machinery to digest plant cell walls, complex carbohydrates like cellulose, or most plant-derived compounds. Their digestive fluid is optimised for breaking down animal proteins, fats, and the structural components of invertebrate prey. Offering fruits, vegetables, or any plant material to a tarantula is pointless at best and potentially harmful at worst. Even feeder insects should be plant-based in their own diet since the tarantula is ultimately consuming whatever nutritional compounds are stored in the prey’s gut and tissues, which is the principle behind gut loading discussed in our article on can tarantulas eat dubia roaches.
Their Role in the Ecosystem
As carnivores, tarantulas occupy an important position in the food webs of the ecosystems where they are found. They are significant predators of insect populations, particularly in tropical and subtropical regions where insect diversity is highest. The Butterfly Pavilion, which conducts ecological research on wild tarantulas, notes that these spiders serve important ecological roles as predators controlling insect populations, as well as prey for other species. Research on burrowing tarantula species in Uruguay even documented individual spiders consuming tens of thousands of beetle pest larvae per hectare per month in grassland habitats, a level of predation that has genuine agricultural relevance.
Tarantulas are themselves prey for a range of predators including birds, lizards, snakes, coatis, and most famously the tarantula hawk wasp, Pepsis sp., which paralyses tarantulas and uses them as living hosts for its larvae. This places tarantulas squarely in the middle of complex food web relationships rather than at either extreme. Burrowing species also contribute to soil aeration in ways comparable to earthworms, making their ecological footprint broader than their diet alone would suggest. See our article on tarantula predators for a full breakdown of what hunts these spiders in the wild.
What This Means for Captive Feeding
Understanding that tarantulas are strict carnivores whose digestion is built entirely around processing animal matter makes it much easier to think clearly about captive feeding. Every meal needs to be an animal-based prey item. The nutritional quality of that prey matters enormously since the tarantula can only work with what the feeder insect contains, which is why gut loading is so important and why dietary variety across multiple feeder species produces better long-term health outcomes than relying on a single insect type. Crickets, dubia roaches, waxworms, hornworms, superworms, and earthworms each bring a different nutritional profile, and rotating between them provides something closer to the dietary diversity a wild tarantula would experience naturally.
Building a feeding routine that reflects your tarantula’s nature as an obligate carnivore is one of the foundations of keeping these animals well. For all the feeders, enclosures, and tools that support good tarantula husbandry from the ground up, our best tarantula products page is a good place to start.