Piero Fariselli
In the book 'Goblet of fire' by
JK Rawlings a poor spider has been
used to show the unforgivable curses to the students. Actually, in the
corresponding movie, the creature was not a true spiders but a digital version
of an arthropod normally known as 'whip spiders' or 'tailless whip scorpions'.
These arthropods do really exist in nature, even though they are really
difficult to meet. Scientifically known as Amblypygi, they are not spiders,
they do not produce silk nor have poison glands, but are spider kin. Like
spiders, Amblypygi possess four legs, a pair of palps (which are leg-like
appendages) and chelicerae (the jaws). The palps are modified in raptorial arms
with a spiny basket shape for capturing prey. Young usually have reddish palps
with banded legs, while adults are colored more uniformly.
Phrynus sp. male
This stunning animals are quite
large to be arthropods, reaching a body length of several centimeters (3 or
more). Despite of the fact that they have a terrifying aspect they are
completely harmless for the humans. Of course this is not true for other
smaller animals which can easily become their preys. Among whip spiders typical
dishes we can number crickets, moths, and sometimes small vertebrates like
young lizards an frogs.
The name 'whip spiders' comes
from the fact that their first pair of legs (whip-like) are very long and thin.
Whip spiders are almost blind and have nocturnal habits, they are also frequent
in proximity of caves. For this reason their first long legs, that carry a lot
of receptors, are the most important sensorial organs of these animals and are
used to scan the environment. Typically they walk keeping one of the leg ahead
and the other around their body. Another interesting characteristic is the fact
that they can move laterally in crab-like way. However, when they need are
really fast. The first time I met one, I approached him (probably was a male)
too close and in a eye-blink he suddenly disappeared a meter apart in a rock
cracks.
Phrynus sp.
walking
They mainly live in humid
tropics and subtropics, so that for an European like me it is necessary to go
abroad to find them, looking in cracks and crevices between rocks, under loose
bark, logs, and litter. During the day, it is more difficult to meet them,
since they hide themselves. But of course if you are not well trained or you
are not helped by a local entomologist guide you may waste a lot of time
looking in wrong places!
I was quite fortunate founding
three of them during a night walk in the 'Parque Nacional del Este' in the
Dominican Republic.
Whip spiders are generally
solitary, however it has been reported that a single tree trunk may house many
individuals in different hides. Males change its daily rest location more
frequently than females. This is probably due to the fact that males move to
find new mating opportunities.
Males are quite aggressive and
often perform a ritualized 'dance' when they encounter other males and
concomitantly there are no females around. However, when females are present
the males duel with other males by using their palps and jaws together to
combat, usually until one abandon or fall on the ground.
Phrynus body
The reproductive
behavior is quite similar to that adopted by scorpions. The male deposits a
spermatophore (a packet with the male sperm), guides the female over it during
the mating courtship until she collects the packet. Living in a wonderful
climate with a perennial spring, they also have a never-ending reproductive
season.
The females carry
their eggs (generally from twenty to forty) under their abdomen for several
months, and again similarly to scorpions the newly hatched whip spiders are
carried for other several days on the back of the mother's body. This until the
first molt, when they leave their mother to start their own adventure.