Overview

The Goliath birdeater (Theraphosa blondi) is one of the largest spiders in the world by mass and legspan. It belongs to the tarantula family and is best known for its impressive size and ground-dwelling habits. Observers gave it the descriptive common name after reports of individuals eating small birds; this behavior is opportunistic rather than a routine diet item. For general background on tarantulas see tarantula.

Physical characteristics

Adults have a heavy, robust body and dense covering of hairs. Typical maximum measurements reported for large specimens include a leg span up to 28 cm (around 11 in), a body length approaching 12 cm, and weights that can exceed 150 g in the heaviest individuals. They possess large chelicerae and pronounced fangs, but these serve primarily to subdue prey. The body hairs include specialized barbed hairs that the spider can release as a defensive measure; contact with these hairs can irritate skin and eyes.

Habitat and behavior

Goliath birdeaters inhabit lowland rainforest regions of northern South America and are typically associated with moist, often swampy terrain where they excavate or occupy burrows. They are mostly nocturnal ambush predators, spending daylight hours in retreats and emerging at night to hunt. Their burrows may be lined with silk and are used for shelter, molting, and raising young. See regional habitat notes at northern South America and burrow ecology references at burrows and swampy habitat sources.

Diet and predation

Goliath birdeaters are opportunistic feeders capable of taking a wide variety of prey. Typical items include:

  • Insects and other large arthropods
  • Lizards, frogs, and other small amphibians
  • Small mammals such as rodents and sometimes bats
  • Occasionally small birds, which inspired the name — reports include prey as small as a hummingbird and other small birds
  • Other small vertebrates such as snakes when encountered

They kill prey primarily with mechanical force from their chelicerae and by applying venom. The venom is generally considered mild to humans and produces localized pain and swelling rather than systemic toxicity; for more on venom see venom.

Reproduction and lifespan

Females produce egg sacs containing on the order of 100–200 eggs; incubation lasts a number of weeks to a few months before spiderlings emerge. Females exhibit maternal behaviors such as guarding the egg sac and sometimes carrying young on their dorsum for a period after hatching. Sexual cannibalism and male mortality after mating have been reported in the wild and in captivity. Lifespan differs markedly by sex: females may live for many years, often approaching two decades in favorable conditions, while males typically live only a few years after reaching maturity.

Human interactions and conservation

Goliath birdeaters are not considered dangerously venomous to people, but they can deliver a painful bite and their urticating hairs can cause irritation or eye problems if mishandled. They are sometimes collected for the exotic pet trade and are affected by habitat loss due to deforestation and development in parts of their range. Conservation concerns focus on habitat protection and responsible collection; for practical handling and safety advice consult targeted resources and local guidelines.

For more species-specific information and natural history details, see targeted entries on prey and behavior at insects, rodents, and regional fauna lists at northern South America. Additional reading on defensive structures and anatomy is available via fangs and venom resources.