Family: Mimetidae (pirate or cannibal spiders)
(animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra >
Arthropoda > Arachnomorpha > Cheliceriformes > Chelicerata > Euchelicerata
> Arachnida > Araneae
The Mimetidae, with the Scytodidae
(spitting spiders), are the stealth fighters of the spider world. Due to their
araneophagous habit of preying mainly on spiders, they are commonly referred to
as pirate or cannibal spiders. They are harmless to man.
Mimetus sp. from the De Hoop
Nature reserve near Bredasdorp. [image N. Larsen
Mimetids are small spiders (3 to 7 mm long) and are
intermediate between the Aranaeidae and the
Theridiidae in appearance. They are pale
yellow to brown in colour with the cephalic area (head area around the eyes)
dark brown. The abdomen is usually marked with yellow and brown speckles and
variegations. The legs are usually banded. The two anterior legs are long and
slender and the tibia and metatarsus of these anterior legs are armed with
rake-like macrosetae (socketed hairs) that are interspersed with smaller
macrosetae, all situated prolaterally - a diagnostic feature of the family. The
globose abdomen usually has two dorsolateral (on top at the sides) humps and has
isolated, scattered setae.
Prey capture was first described in Britain by W. S.
Bristow in 1958. From his and further Australian research, it appears that they
prey mainly on web-living Araneidae and Theridiidae but also on Agelenidae,
Dictynidae, Linyphiidae, Tetragnathidae and the cursorial Philodromidae,
insects, Lepidopteran larvae, spider eggs and they also steal the prey from the
webs of spiders.
Mimetids can normally be observed at dusk suspended from a
few silk strands at the edge of a spider web. This would not be its own web but
that of another spider as it does not construct a web of its own. At night it
will vibrate the web, mimicking either captured prey or a courting male spider
of the species that occupies the web. The duped spider will rush to investigate
and once within reach, the mimetid will move forward with such stealth that the
movement is barely noticeable. The four anterior legs are stretched over its
prey and it is quickly drawn forward, its legs pinned down with the spines on
the attackers forelegs. The mimetid then bites the prey in the femur, instantly
immobilizing it. It is not known whether the bite kills or merely paralyzes.
Bristow observed that if the prey is bitten on the body, a vigorous struggle
ensues that requires an additional bite to the legs to subdue it.
While mimetids are ferocious on the attack, they are gentle
during courtship - albeit one of the briefest courtships in the spider world.
The female produces 3 cocoons each suspended from silk thread and each
containing about 8 eggs.
The Mimetidae family includes 12 genera, four of which
occur in the Afrotropical region of which Ero and Mimetus occur in South Africa
each with two species.
Genera indigenous in southern Africa
Ero capensis and Ero lawrencei occur in the Western and
eastern Cape respectively. In Ero, the length of the first pair of
legs is 1.3 (or less) times the length of the fourth pair.
Mimetus cornutus and Mimetus natalensis are both recorded from
Kwazulu Natal, its interesting to note that the Mimetus species
illustrated above was photographed at the de Hoop Nature Reserve near
Bredasdorp illustrating the need for further work on the group. In the genus
Mimetus, the length of the first pair of legs is 1.5 times the length
of the fourth pair of legs.