like other arthropods, spiders coelomates in coelom reduced small areas round reproductive , excretory systems. place largely taken hemocoel, cavity runs of length of body , through blood flows. heart tube in upper part of body, few ostia act non-return valves allowing blood enter heart hemocoel prevent leaving before reaches front end. however, in spiders, occupies upper part of abdomen, , blood discharged hemocoel 1 artery opens @ rear end of abdomen , branching arteries pass through pedicle , open several parts of cephalothorax. hence spiders have open circulatory systems. blood of many spiders have book lungs contains respiratory pigment hemocyanin make oxygen transport more efficient.
spiders have developed several different respiratory anatomies, based on book lungs, tracheal system, or both. mygalomorph , mesothelae spiders have 2 pairs of book lungs filled haemolymph, openings on ventral surface of abdomen allow air enter , diffuse oxygen. case basal araneomorph spiders, family hypochilidae, remaining members of group have anterior pair of book lungs intact while posterior pair of breathing organs partly or modified tracheae, through oxygen diffused haemolymph or directly tissue , organs. trachea system has evolved in small ancestors resist desiccation. trachea connected surroundings through pair of openings called spiracles, in majority of spiders pair of spiracles has fused single 1 in middle, , moved backwards close spinnerets. spiders have tracheae have higher metabolic rates , better water conservation. spiders ectotherms, environmental temperatures affect activity.
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