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Myrmarachne
maxillosa waving
its front legs in mid-air |
Some
Jumping Spiders assume the appearance of an ant by having long and
slender legs and what appears to be a three-part (head-thorax-abdomen)
body of an insect. To add further to the deception, the fore-legs
are often raised in the air like a pair of antennae. |
Some scientists believe
that by mimicking ants, the spiders deceive their ant-models and prey either
on the ants themselves, or on the homopteran bugs "tended" by
the ants. However, it should be noted that the ant-mimicking Jumping Spiders
in Singapore have never been observed to have attacked the ants they imitate.
A more plausible explanation is that by copying the physical appearance
of ants, the ant-mimicking Jumping Spiders are actually buying insurance
for self-protection, since spider-hunting wasps, birds and other spider-predators
generally avoid ants which secrete the distasteful formic acid when attacked.
| There
are two genera of anti-like Jumping Spiders in Singapore. The more
common Mymarachne have a long waist (pedicel) and an elongated
cephalothorax with a constriction dividing the higher cephalic region
and the lower thoraxix part. The jaws of Myrmarachne spider,
especially the males, are enormously enlarged and project in front
making the spider appear to be a soldier ant. |
The
enormous jaws of a male Myrmarachne plantaleoides |
The cephalothorax of
the spiders of the genus Agorius is also divided into distinct "head"
and "thoracic" regions but the division is not as obvious as that
shown in Myrmarachne. The most diagnostic feature of Agorius
spiders is that the first pair of legs are exceedingly long. The third last
segments (patella) of the fore-legs are conspicuously more elongated than
those of other spiders.
 These
Myrmarachne spiders copy different species of "red ants".
Take a closer look and note the differences. Check the following:
- Colour of the "head".
- Colour of the abdomen.
- Constriction, if any, at the abdomen
 
For more about
ant-mimicking Sac Spiders Castianerira and
Apochinomma. |
Here
are a few species of
ant-mimicking Jumping Spiders
found in Singapore...
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