Main Characteristics of Arachnids

• There are 110,000 species of arachnids.
• 51,000 are spiders, 50,000 are mites, 6,600 are harvestmen, and 3,500 are scorpions.
• Arachnids always have eight legs. Insects only have six legs.
• Arachnids don't have a good sense of sight, but they do have an excellent sense of touch.
• Arachnids have two body parts: a front and a back section. The head is fused with the front section.
• Insects have three body parts: head, thorax, and abdomen.
• Spider silk is produced as a liquid in the spinnerets. It is excreted through spinnerets and spun into threads outside the body.
• Threads made from spider silk are incredibly strong yet flexible. They can even withstand four to five times more stress than threads made of steel.
• However: Not all spiders create a web from fine threads. Only 2,800 species do that.
• Almost all spiders possess venom glands. These are located in the front section and they deliver the venom through their sharp fangs or pincers into their prey.
• In the USA, the most dangerous spiders are the black widow and the brown recluse spider.
• In Germany, there are only four spiders that can penetrate human skin with their chelicerae: the yellow sac spider, the diving bell spider, the Nosferatu spider, and the garden spider. While their venom does cause pain, it is not lethal.
• Australia is home to the majority of venomous spiders.
• The most dangerous venomous spiders are the Brazilian wandering spider (South America) and the Sydney funnel-web spider (Australia).
• The largest spider is the Goliath bird-eater. It has a wingspan of 11-12 inches (28-30 cm) and can weigh up to 6.2 ounces (175 grams).
• The smallest spider is the web spider Patu digua, which belongs to the family Symphytognathidae. It measures only 0.015 inches (0.37 mm) in length.
• The fastest spider is the Moroccan flic-flac spider. It can run at speeds of up to 3.8 mph (6.12 km/h). In just one second, it can cover a distance that is 100 times its body length.
• Scorpions are also part of the arachnids. Scorpions have two pincers and a venomous stinger on their tail. Out of 3,500 species, around 25 are dangerous to humans.
• Ticks are also arachnids. They belong to the order of mites within the arachnids. They can transmit Lyme disease and tick-borne encephalitis.

Arachnid Family Tree

Species List