Scytodes thoracica

Scytodes thoracica is a spitting spider, so called because it spits a venomous sticky silken substance over its prey. Its size ranges between 3–6 mm (0.12–0.24 in). The carapace is unusual in sloping upwards towards its rear end, whereas the abdomen slopes downwards.

Scytodes thoracica
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Class:	Arachnida
Order:	Araneae
Infraorder:	Araneomorphae
Family:	Scytodidae
Genus:	Scytodes
Species:	S. thoracica
Binomial name
Scytodes thoracica (Latreille, 1802)
Synonyms
Aranea thoracica Scytodes tigrina Scytodes cameratus Loxoscelis thoracica

It has six eyes instead of the eight spiders usually have. It has a wide distribution, being found in Europe, North Africa, Turkey, temperate Asia to China, Korea and Japan. It has been introduced to North America, Argentina, India, Australia and New Zealand.^[1]

This particular spitting spider features the presence of silk glands in its cephalothorax. Besides the silk glands in its abdomen, the spider also has silk glands connected with its venom glands. In this way the spider has the ability to make venomous silk. Other arachnids may also have silk glands in their cephalothorax, such as the pseudoscorpions.

Hunting tactics

Schematic illustration of an immobilised prey

In contrast to the pseudoscorpions that use the silk from the cephalothorax glands to make nests, the spitting spider uses it to catch prey in a very particular way. It is a very slow hunter as its long and tender legs may suggest. During night, when some insects are less active, Scytodes starts its hunt. The spider sneaks very carefully towards its prey and, from about 10 mm (0.39 in), stops and carefully measures the distance to its prey with one front leg without disturbing it. Then it squeezes the back of its body together and spits two silk threads, in 1/600 s, in a zigzag manner over the victim. The prey is immediately immobilized. When the prey is larger the spider spits several times. It is assumed the spider uses special long hearing hairs located at its legs to locate its prey.^[2]

Habitat

Scytodes thoracica in Essex, England.

Scytodes thoracica is nocturnal and can be found worldwide, particularly in Europe. It prefers warm temperatures and can be found inside houses or underneath stones.^[2] In the UK, its range rarely stretches beyond southern England, with few recorded sightings beyond there.^[3]

Reproduction

The mother makes a nursery web for the emerged spiderlings, and carries her eggs under her belly in a net of silk.^[2]