''Celaenia excavata'', the bird dropping spider of

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

, derives its name from mimicking bird droppings to avoid predators, mainly birds. However, there are other species of spider that resemble bird droppings, for example species of '' Mastophora'' (a

bolas spider A bolas spider is a member of the orb-weaver spider (family Araneidae) that, instead of spinning a typical orb web, hunts by using one or more sticky "capture blobs" on the end of a silk line, known as a "bolas". By swinging the bolas at flying ...

Habitat and appearance

The males are much smaller than the females, about 2.5 mm as opposed to 12 mm. The females have up to 13 egg sacs, with about 200 eggs each, strung together with strong threads. Their

toxic Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

ity is unknown, but may be able to cause mild illness in humans. ''Celaenia excavata'' is found throughout large parts of eastern and southern

and have also been recorded in central Australia; they are also seen in suburban gardens. The egg sacs of the bird-dropping spider are large, marbled brown colored spheres, each about 12 mm in diameter and containing over 200 eggs. Up to 13 sacs are silked together in a group, beneath which the spider may be found awaiting prey.

Hunting

Its diet consists almost exclusively of male moths, which it hunts at night by mimicking the scent of female moths. The bird dropping spider stays motionless on its web during the day, only hunting for prey at night. It hangs down from a single silk thread and releases a

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

which mimics the

sex Sex is the trait that determines whether a sexually reproducing animal or plant produces male or female gametes. Male plants and animals produce smaller mobile gametes (spermatozoa, sperm, pollen), while females produce larger ones (ova, oft ...

smells released by female moths. When a moth comes near, the spider will capture it with its powerful front legs.

References

External links

University of Southern Queensland: Bird dropping spider

{{Taxonbar, from=Q4289148 Araneidae Spiders of Australia Taxa named by Carl Ludwig Koch Spiders described in 1867 Spiders of New Zealand