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Field guide training: Arthropods –Part 3
Essential knowledge about spiders, scorpions and mites is particularly important for a field guide. In this blog post you can learn more about these special representatives of the arthropods.
Arachnids – The vigilant hunters
The group of the arachnids comprises the species of spiders, harvestmen, scorpions, pseudoscorpions and mites. The most important species a field guide in Southern Africa should know about are spiders (araneae), scorpions (scorpiones) and mites (acari).
The most obvious characteristic to distinguish insects and arachnids is the number of legs: Insects mostly only have six legs whereas spiders have eight. Furthermore, spiders have two body parts consisting of cephalothorax und abdomen. Their eight eyes are set on the front of their cephalothorax. Their sensory perception occurs through fine hairs which are spread all over the spider’s body and can even sense small vibrations in the air or on the ground.
Most spiders are carnivores, which means that they feed from other animals and are on top of the food chain. To catch their prey, they use different strategies. Many spiders construct nets to catch their prey while others build small tunnels out of spider silk which they hide in to wait for the right moment to attack their prey. Meanwhile scorpions make use of their strong pincers to catch their prey. A totally different strategy is applied by mites: They live from other animals and feed on their blood as parasites. A very well-known species which is known for this behaviour are the ticks (Ixodida).
Many spiders and scorpions are equipped with strong venoms that can be cytotoxic or neurotoxic. A detailed knowledge about the poisonous species in the area of training of a field guide and the adequate behaviour in case a bite or sting occurs can be vital. Therefore, below a few important information and behavioural guidelines are listed regarding spiders and scorpions.
All spiders have poison glands and produce venom. But this does not mean that all spiders are dangerous for humans. Most spiders are not dangerous at all for humans, because their venom is to weak or their cheliceras not strong enough to penetrate the human skin. Here are a few species which humans should be aware of, though:
- Black Button Spider (Latrodectus indistinctus) one of the most dangerous spiders in South Africa
- Sac Spider (Clubionidae) an aggressive spider with a painful bite
- Violin Spider (Laxoscelinae)has a very strong cytotoxic venom
- Six-Eyed Crab Spider (Sicariidae) also have a very string cytotoxic venom
- Small Baboon Spider (Harpactirella lightfooti) their neurotoxin is not very strong, but their bite is painful
- Buthidae (Parabuthus) a scorpion species with a strong neurotoxin that paralyzes the breathing and cardiovascular system.
If a bite of any of the above listed species occurs the person should immediately be medically treated, especially when bitten by a Black Button Spider, Sac Spider, Violin Spider, Six-Eyed Crab Spider or Scorpion.
In contrast to spiders and scorpions, mites are rarely poisonous but are often carrier of diseases, especially ticks. The best protection for tick bites are long sleeved cloth, insect repellant and to check your body for ticks after being the bush.
