| * |
HABITAT
Trapdoor spiders dig burrows in the ground with their fangs. The
fangs are mounted on mobile "turrets" that contain poison glands. Each turret
has a comb of spines on its underside. The spider uses the comb to sweep soil into pellets
that it dumps outside.
A hinged lid, or trapdoor, fits neatly in the mouth of the burrow.
Some are thin flaps, but most are thick slabs made of silk and soil. The spider chisels
the edges of the lid with its fangs to get an exact fit. It attaches it with a silk hinge
and covers the top with plant debris.
The result is a perfectly camouflaged retreat. It
provides protection against the weather and most predators and is an ideal lair from which
to pounce.
Above: When in danger, the trapdoor
spider adopts a threat Posture and displays its fangs.
ENEMIES
Despite their well-defended homes, trapdoor spiders are vulnerable
to spider-hunting wasps. The wasp can flip back the trapdoor, dive in, and paralyze the
spider with a sting. Some spiders cling to the trapdoors, but the wasp simply slices
through the door with its shearing jaws. The wasp then lays an egg. When it hatches, the
wasp grub eats the spider.
Some spiders strengthen their defenses. Several species
build complex burrows with side chambers and extra doors. An Australian species digs a
Y-shaped burrow with an escape tunnel. |
* |
Trapdoor spiders are masters of
ambush. These killers lurk in their perfectly camouflaged lairs, ready to pounce on any
insects that stray too close.
BREEDING
For the male spider, mating can be hazardous. The female,
which is usually larger, may not recognize him as a suitor. Conditioned by her predatory
instincts, she is likely to regard him as a meal. Females rarely stray far from their
burrows.
The male is guided by a pheromone (a special
chemical attractant) that the female releases and by the distinguishing pattern of silk
around her burrow. Some males perform courtship dances. They drum their legs in a way that
seems to lull the female into a state of receptiveness. Then the male impregnates her with
a drop of sperm from a capsule on the end of his palp (feeler).
The eggs are laid in the burrow, in a cocoon attached to
the silk lining. The hatchlings look like miniature versions of their mother and stay with
her for several weeks.
Above: The trapdoor spider stays half
inside the burrow as it waits for prey to pass by.
|
* |
FOOD & HUNTING
The hunting methods of trapdoor spiders vary according to habitat.
Species living in moist places with plenty of insects can rely on the ambush. At night the
spider lurks at the entrance to its burrow. It puts out its front two pairs of legs, which
have hairs that are sensitive to ground vibrations. When a victim passes by, the spider
lunges forward and strikes.
Some trapdoor spiders live in drier habitats,
where there are fewer insects. These species have better eyesight and longer legs. They
often pursue their quarry for some distance from the burrow.
Some species lay traps for their prey. They stretch
silken trip wires from the burrow or even small twigs wired with silk. At the slightest
twitch, the spider rushes out and plunges its fangs into the victim. The venom kills the
prey in seconds and begins to digest its tissues, making a soup the spider can suck up at
leisure.
KEY FACTS
Length: About 1 in.
Mouthparts: Pair of downward-pointing poison
fangs for piercing, crushing, and digging.
Eyes: 4 pairs of simple eyes.
Breeding season: Summer in temperate regions;
year-round in the tropics.
Eggs: Laid in burrow. Number varies according to
species.
Habit: Stays in burrow by day and ambushes prey
from burrow by night.
Diet: Ground-dwelling insects and other
invertebrates.
Lifespan: Normally 1-2 years. |
* |
Did You Know?
A female trapdoor spider may spend her whole life inside her
burrow, enlarging it as she grows.
Trapdoor spiders can move up to 140 times their own weight.
In arid areas trapdoor spiders often build burrows under a tree to
snare insects attracted to the tree's moisture.
Some Australian trapdoor spiders build walls around burrow
entrances as protection against flooding.
The spider strikes so quickly that it occasionally drags inedible
prey into its burrow by mistake. |
|
