Spiders that don't have book lungs and breathe through trachea include members of the spider families Caponiidae and Symphytognathidae. Most spiders that breathe using only trachea have a single spiracle on the underside of their abdomen. Spiders transport oxygen around their bodies in hemolymph, a blue, blood-like substance.
Although spiders do not have specialized blood cells like red cells in humans, hemocyanin works in a similar way to red blood cells. Hemocyanin binds to oxygen and releases it in areas with low oxygen concentrations, and transports waste carbon dioxide to areas where it can diffuse out into the atmosphere.
Spiders have a single-chambered, tubular heart, arteries and veins, but they do not have capillaries. Spider hearts have valves to keep their hemolymph flowing in the same direction and to prevent it from flowing backward.
When spiders are excessively active, muscle contractions cause hemolymph to move around the body, increasing the transportation of gases. A graduate of Leeds University, Jenny Green completed Master of Arts in English literature in and has been writing about science since Green's work appears in Synonym, Sciencing, and other websites and ezines. Related Articles Role of the Lungs. What Are the Functions of the Spiracles? The Respiratory System of a Butterfly.
One of the reasons bioactive terrariums are beneficial for arachnids in particular is that it helps them to breathe by adding more moisture to the environment and even indicating when the habitat is dry.
The reason humidity levels are so important to respiration for animals like tarantulas is because they breathe through sets of organs called book lungs. This article covers more on what book lungs are and how tarantulas and other arachnids use them to breathe. Tarantulas have two sets of book lungs, for four book lungs in total. Book lungs are stacks of ten to eighty hollow, leafy disks.
The number of hollow disks stacked depends on the species of spider. Spiders, such as tarantulas, in the Mygalomorphae infra-order and Mesothelae suborder, have two pairs of book lungs. Scientists have found that many primitive spider species have the feature of a set of book lungs compared to just one pair.
The book lungs are saturated in light blue haemolymph. Haemolymph is similar to blood for a spider. Then the book lungs or trachea, depending on the spider, filters the oxygen for absorption and releases carbon dioxide into the air through a process called diffusion. Haemolymph is very similar to the hemoglobin that carries iron-rich nutrients. In the case of spiders, hemocyanin, which is a protein-rich respiratory pigment, carries oxygen and carbon dioxide within haemolymph instead.
Haemolymph is a light blue color due to the copper atoms it carries as well. The tracheae are long tubes that start at small holes on the underside of the exoskeleton and extend through the body of the spider providing oxygen to internal organs.
Air is absorbed through the skin or very small trachea holes located on the underside of the spider's abdomen. It is a common belief of arachnologists and entomologists that the trachea is a new feature that was integrated with genetic adaptation. Some species with this trachea feature include wolf spiders, orb spiders, and daddy longlegs. The spider must move to allow the book lungs to work.
The movement of a spider provides the necessary energy for air to be pushed in and out of the book lungs or trachea. However, spiders require less oxygen than people do. Therefore they can go hours to even days without breathing. This is why they can stay so still in their web waiting for their next meal or why you can capture a spider in a jar without holes and they can be still alive days later.
So be careful the next time you choose to capture a spider specimen. It may still be alive when you open the jar days later. Although the respiratory system of a spider is much simpler compared to mammals, the inner workings of a spider are amazing. They are very resilient creatures, so don't underestimate the survival rate of spiders.
They are equipped to survive the toughest of times and circumstances.
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