Spiders

[Tshokwane]

Credits to The Silk Road

Six legged Pisaura mirabilis, Nursery web spider.

If a spider is injured on the abdomen (opisthosoma), it usually amounts to a death sentence. Spiders have an open network which means its arteries carry haemolymph, the arthropod equivalent of mammalian blood, out into the tissue spaces where it diffuses past individual cells before being collected back into the heart. There are few, if any, veins in this system and definitely no capillaries. So if there is an injury which causes an opening in the side of the body, this fluid leaks out and the animal dies. Losing a leg or two is a different ball game altogether. At the joints of the legs the spider has sphincters which close off therefore saving the spider from bleeding to death.

*This image is copyright of its original author

Reply