Tarantulas eat by using their hollow fangs to inject digestive enzymes into prey, liquefying the internal tissues so they can suck up the nutrient-rich fluids.
Tarantulas fascinate pet owners and arachnid enthusiasts alike, but their feeding habits differ wildly from mammals. You won’t see chewing or swallowing of solid chunks. Instead, these spiders rely on a strictly liquid diet derived from solid animals. The process involves ambush tactics, potent venom, and external digestion.
Understanding this biological mechanism helps keepers provide better care. It also clarifies why a tarantula leaves behind a small, dry ball of indigestible material after a meal. This guide breaks down the anatomy, timing, and specific steps of the arachnid dining experience.
The General Mechanics Of Arachnid Digestion
Most people assume spiders bite and swallow. The reality is far more complex and efficient. A tarantula acts as a mobile processing plant. It turns live insects or small vertebrates into a slurry before ingestion occurs. This method allows them to absorb a high volume of nutrients without a heavy internal digestive system.
The spider relies on two main tools: chelicerae and the sucking stomach. The chelicerae are the strong jaws that hold the fangs. The sucking stomach acts like a pump. It creates a vacuum to pull the liquefied food into the gut. Without this pump, the spider would starve even with prey in its mouth.
Tarantula Dietary Spectrum Overview
Different species prefer different meals depending on their size and habitat. This table outlines common prey items and their role in the spider’s nutrition.
| Prey Type | Nutritional Value | Suitability Note |
|---|---|---|
| Crickets | High Protein, Low Fat | Staple for most captive spiders. |
| Dubia Roaches | High Protein, High Calcium | Excellent meat-to-shell ratio. |
| Mealworms | Moderate Fat, Chitin | Burrow quickly; supervise feeding. |
| Superworms | High Fat | Treat only; can bite back. |
| Hornworms | High Moisture, Low Fat | Great for hydration boosts. |
| Pinky Mice | High Calcium, Heavy Fat | Adults only; use sparingly. |
| Fruit Flies | Low Nutrient Density | Strictly for spiderlings (slings). |
| Locusts | Balanced Protein | Popular in regions outside the US. |
Step By Step: How Do Tarantulas Eat?
The feeding event follows a strict biological script. Whether in the wild rain forests of Brazil or a glass enclosure in a bedroom, the steps remain identical. The spider does not rush. It conserves energy until the precise moment striking guarantees success.
Sensing The Vibrations
Tarantulas have poor eyesight compared to jumping spiders. They do not hunt by sight. They rely on mechanoreceptors. These are tiny sensory hairs on their legs called trichobothria. These hairs detect air currents and ground vibrations.
When a cricket walks nearby, the spider feels the footfalls. It can pinpoint the exact location and size of the prey without seeing it. This sensory system is so sensitive it can detect the wing beats of a flying insect.
The Strike And Envenomation
Once the prey is within range, the tarantula lunges. This happens in a fraction of a second. The spider uses its front legs to grab the victim. Simultaneously, it sinks its fangs downward. This is a key difference from true spiders, whose fangs pinch sideways. Tarantula fangs strike vertically, like pickaxes.
Venom flows through the hollow fangs immediately. This venom serves a dual purpose. First, it contains neurotoxins to paralyze the prey. This prevents the insect from injuring the soft abdomen of the spider. Second, the venom begins the chemical breakdown of tissue.
External Digestion Process
This stage answers the question: how do tarantulas eat if their mouths are tiny? They vomit digestive fluids onto and into the prey. These enzymes dissolve muscle, fat, and internal organs. The prey’s body becomes a container for its own soup.
The spider holds the prey with its pedipalps (the smaller appendages near the mouth) and chelicerae. It rotates the “food bolus” slowly. This ensures the enzymes reach every part of the meal. This process takes hours. A large meal might require the spider to sit still with the prey for an entire day.
Filtration And Ingestion
The mouth opening sits behind the fangs. It has hairs that act as a filter. These hairs stop large solid particles from entering the gut. The sucking stomach pumps rhythmically. It draws the nutrient fluid through the mouth and into the midgut.
When the spider finishes, only a small, dry ball remains. Keepers call this a “bolus.” It consists of wings, legs, skull fragments, and hard exoskeleton pieces that the enzymes could not dissolve. Finding these boluses is a clear sign your pet is eating well.
Anatomy Of The Feeding Apparatus
To fully grasp this process, look closely at the mouthparts. The prominent fuzzy appendages are not just legs. The two short limbs near the fangs are pedipalps. In mature males, these double as reproductive organs, but for eating, they function like hands.
The fangs fold under the body when not in use. When the spider threatens or eats, they extend. Between the chelicerae lies the oral opening. Inside the body, the digestive tract runs all the way to the spinnerets. The stomach has powerful muscles attached to the inside of the carapace (the top shell). When these muscles contract, the stomach expands, creating the necessary suction.
The Australian Museum details spider structure, noting how the sucking stomach is lined with cuticle to withstand the pressure of pumping. This structural reinforcement is vital because the liquid food is often thick and viscous.
What Do Wild Tarantulas Eat?
Wild tarantulas are opportunistic feeders. They do not discriminate as long as the prey fits their size constraints. Their diet depends heavily on their location. Arboreal (tree-dwelling) species encounter different prey than terrestrial (ground-dwelling) species.
Insects And Arthropods
The bulk of a wild diet consists of beetles, grasshoppers, millipedes, and other spiders. Large centipedes are common prey, though they fight back hard. In deserts, tarantulas may consume scorpions. The tarantula must strike quickly to avoid the scorpion’s sting.
Vertebrate Prey
Despite the name “bird-eater” attached to the Goliath Birdeater (*Theraphosa blondi*), birds are rare treats. However, large tarantulas regularly consume small lizards, frogs, and snakes. Rodents are also on the menu. A mouse provides a massive amount of calories. A single vertebrate meal can sustain a wild female for months.
Scavenging is less common but happens. If a tarantula finds a fresh carcass, it may attempt to feed. However, they prefer live movement to trigger their hunting instinct.
Hydration: Do Tarantulas Drink?
Yes, tarantulas drink water. They cannot survive on food moisture alone, especially in captivity. A tarantula drinks by lowering its mouthparts into a water source and using the same sucking stomach action used for eating.
Dehydration kills spiders faster than starvation. A dehydrated tarantula will have a shriveled abdomen. Its legs may curl underneath its body, a condition often called a “death curl.” Keepers must provide a shallow water dish. Sponges harbor bacteria and should be avoided.
The Fasting Phenomenon: Premolt
New owners often panic when their tarantula stops eating. Refusing food is a standard part of the tarantula life cycle. This period is called premolt. As the spider prepares to grow, it grows a new exoskeleton underneath the old one.
During this time, the spider separates from its old shell. The fangs also soften. If a tarantula tried to eat with soft fangs, it would break them. Therefore, biology dictates a total fast. This fast can last from a few weeks to several months depending on the age of the specimen.
Signs of premolt include:
- A darkening abdomen (the new skin showing through).
- Sluggish behavior.
- Sealing off the burrow entrance with webbing.
- Refusal of food for consecutive feedings.
Do not leave live prey in the enclosure during this time. A cricket can chew on a molting tarantula, causing fatal injuries.
Feeding Captive Tarantulas Correctly
Captive diets mimic the wild but remove the risks. You control the nutrient intake. Gut-loading feeder insects is the best way to ensure health. Gut-loading means feeding the cricket nutritious vegetables (carrots, leafy greens) 24 hours before giving it to the spider.
Variety helps. While crickets are standard, switching to Dubia roaches or mealworms offers different fat and protein levels. Avoid wild-caught insects. Insects from your garden might carry pesticides or parasites that will kill your spider.
Frequency And Sizing Rules
Overfeeding is a common mistake. A tarantula with a massive abdomen is at risk of rupture if it falls. The prey should generally be no larger than the spider’s abdomen. For slings (babies), the prey can be the size of the spider’s body, but pre-killed prey is often safer.
The table below helps determine how often you should offer food based on the spider’s development stage.
| Growth Stage | Feeding Frequency | Recommended Prey Size |
|---|---|---|
| Spiderling (Sling) | Every 2–3 Days | Pinhead crickets or flightless fruit flies. |
| Juvenile | Once Per Week | Small crickets or medium mealworms. |
| Sub-Adult | Every 10–14 Days | Large crickets or Dubia roaches. |
| Adult Female | Every 2–4 Weeks | Adult Dubia roaches, superworms, or occasional pinky. |
| Adult Male | Sporadic | Focuses on mating; eats very little. |
Troubleshooting Feeding Refusals
Sometimes a spider refuses food when not in premolt. Stress is a primary factor. If the enclosure is too bright, too loud, or vibrates from foot traffic, the spider may hunker down. Relocating the enclosure to a quiet corner often solves this.
Temperature plays a role. Spiders are ectothermic. If the room is too cold, their metabolism slows down. They digest slower and eat less. Raising the temperature by a few degrees can trigger an appetite. Check the specific requirements for your species, as tropical species have different needs than desert ones.
Another reason is the size of the prey. If a cricket is too large and aggressive, the tarantula might defend itself rather than hunt. If the spider backs away or throws a threat posture (rearing up front legs), remove the prey immediately.
Safety Protocols During Feeding Times
Interaction during feeding requires caution. The spider is in a heightened state of arousal. It strikes at movement. Mistaking a finger for a worm is a painful error for the keeper and dangerous for the spider.
Use long feeding tongs. Never use your hands to drop prey in. Tongs allow precise placement of the food item near the spider without entering the strike zone. If the spider rushes the tongs, you can drop the item and retreat safely.
Urticating Hairs Awareness
New World tarantulas (from the Americas) possess urticating hairs on their abdomens. They kick these hairs when threatened. If you startle the spider while opening the enclosure to feed, it might release a cloud of these irritating bristles. Keep your face away from the opening. Inhalation of hairs causes severe respiratory distress.
Digestion Duration And Metabolic Rates
Digestion speed varies by species and temperature. A heavy meal takes time to process. You might notice the spider’s abdomen swelling hours after eating. This distension is the stomach filling up. It can take several days for the nutrients to fully assimilate and for the abdomen to return to a normal size.
Slow-growing species, like the Grammostola genus (e.g., Brazilian Black), have slower metabolisms. They eat less frequently than fast growers like the Theraphosa or Pterinochilus genera. Adjust your schedule to the individual spider, not just the calendar.
Comparison: How Do Tarantulas Eat Vs True Spiders?
While the mechanism of liquid extraction is similar, the approach differs. Web-building spiders wrap their prey in silk immediately to immobilize it. They wait for the struggle to cease before biting. Tarantulas rarely wrap prey before the bite. They overpower prey with brute strength and heavy fangs.
Tarantulas are primitive spiders (Mygalomorphs). Their fang alignment limits them to striking downward. True spiders (Araneomorphs) possess pincer-like fangs that allow for more dexterity. However, the tarantula’s sheer size allows it to take down prey that would easily escape a common web weaver.
Specific Nutrients For Molting Success
Protein and hydration are the building blocks of a successful molt. The exoskeleton is made of chitin. While spiders synthesize this, they need energy reserves to survive the exhausting molting process. A well-fed spider has a plump, shiny abdomen.
If a spider looks thin (shriveled abdomen) after a molt, wait for the fangs to harden (turn black) before feeding. Offering food too early results in broken fangs, which is a death sentence. Once the fangs are hard, offer a moisture-rich meal like a hornworm to replenish fluids lost during the shell shedding.
For detailed nutritional breakdowns of feeder insects, scientific resources like the Oklahoma State University insect nutrition guide provide data on protein and fat content, helping you choose the right feeder for your pet’s current condition.
Cleaning Up After The Meal
Sanitation prevents mold and mites. Once the spider drops the bolus, remove it. In a humid terrarium, a dead organic ball grows mold within 24 hours. Mites thrive on these leftovers and can infest the spider, covering its mouth and joints.
Use your tongs to search the substrate. Sometimes tarantulas bury their leftovers. Regular spot cleaning keeps the enclosure healthy and reduces the need for full substrate changes. If you smell a foul odor, you likely missed a bolus or a dead feeder insect somewhere in the dirt.
The Role Of Venom Potency
Venom potency correlates with the spider’s origin. Old World tarantulas (Africa, Asia) lack urticating hairs. To compensate, they have potent venom and high speed. Their bite causes severe muscle cramping and pain in humans. New World tarantulas generally have milder venom, relying on their itchy hairs for defense.
Regardless of potency, the venom functions the same way on prey: rapid immobilization and liquefaction. This efficiency ensures the spider spends minimal energy subduing a struggling meal. The less energy spent fighting, the more energy gained from eating.
Winter Fasts And Seasonal Changes
Even in temperature-controlled homes, spiders sense seasonal pressure changes. Many mature tarantulas, especially males, eat significantly less in winter. This is natural. Do not force-feed. Offer food; if rejected, remove it and try again in two weeks. As long as the abdomen remains round and the spider has access to water, a winter fast is no cause for alarm.
Observation is your best tool. Watch the abdomen size. Watch the activity level. These cues tell you more about your tarantula’s hunger than any strict schedule ever could. Respect their biology, and they will thrive.