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In most species the spiracles can be opened and closed in an efficient manner to admit air while reducing water loss. In various species, this is done by a wide range of mechanisms, such as elastic closure, and closer muscles surrounding the spiracle or kinking the tube. In some the muscle relaxes to open the spiracle, in others to close it.
Spiders, like most arthropods, have an open circulatory system, i.e., they do not have true blood, or the veins which transport it. Rather, their bodies are filled with haemolymph , which is pumped through arteries by a heart into spaces called sinuses surrounding their internal organs .
The trachea were originally connected to the surroundings through a pair of openings called spiracles, but in the majority of spiders this pair of spiracles has fused into a single one in the middle, and moved backwards close to the spinnerets. [13] Spiders that have tracheae generally have higher metabolic rates and better water conservation. [17]
Perhaps the most famous group of spiders that construct funnel-shaped webs is the Australian funnel-web spiders. There are 36 of them and some are dangerous as they produce a fast-acting and ...
A book lung is a type of respiration organ used for atmospheric gas-exchange that is present in many arachnids, such as scorpions and spiders. Each of these organs is located inside an open, ventral-abdominal, air-filled cavity (atrium) and connects with its surroundings through a small opening for the purpose of respiration.
When a spider bites, the two parts of the chelicerae come together like a folding knife, and when making a threat display or actually preparing to bite, the spider will open the angle of the fangs with the basal portion of the chelicerae and also open the angle of the basal portion with the cephalothorax. [2]
The spiracles can be opened and closed in an efficient manner to reduce water loss. This is done by contracting closer muscles surrounding the spiracle. In order to open, the muscle relaxes. The closer muscle is controlled by the central nervous system but can also react to localized chemical stimuli. Several aquatic insects have similar or ...
The “classic” Sydney funnel-web spider, Atrax robustus, is found from the Central Coast to the Sydney Basin; the Southern Sydney funnel-web, ...