Sunday, May 1, 2011
Tarantula by Dylan Burchett
The tarantula is a massive family of creatures, found in tropical and desert regions of North and South America, Africa, Australia, New Zealand, and parts of Europe and Asia. Over 900 different species have been discovered. Tarantulas are generally divided between terrestrial types that are prone to burrowing, and arboreal types that build shelters high off the ground.
Depending on the species, the body length of tarantulas ranges from 2.5 to 10 cm, with 8–30 cm leg spans.
Form & Function:
Tarantulas feed by biting its prey, often insects, birds, mice, or lizards, with fangs on the ends of its chelicerae and injecting it with a venom that both paralyzes the prey and liquefies its insides. The tarantula then drinks up the liquefied interior of the prey with its mouth, which is located under its chelicerae on the lower front part of its prosoma. The leftovers of the prey are balled up by the tarantula and thrown away. Reproduction begins when the male spider weaves a web on a flat surface and rubs its abdomen on it to release semen. The male spider then absorbs the semen with its pedipalps, where it is kept until it meets a mate. When it does so, the two will perform various signals to confirm that both are receptive and of the same species. If the female is receptive, the male will insert his pedipalps into the female’s opisthosoma to transfer semen. Later, the female will deposit 50-2000 eggs into an egg sac until its young hatch. Tarantulas protect themselves against predators such as the Pompilidae wasp (“tarantula hawks”) with urticating hairs. Urticating hairs are barbed hairs that are designed to irritate predators and are found on the abdomen. The hairs are not grown back, but are replaced with each molt. The hairs can be extremely lethal to small animals, but are not as dangerous to people, though it ranges by person.
Impact on World/Humanity:
Tarantulas have a large impact on humanity because of their place on the food chain. Their presence is often key to the many ecosystems where they are found as both a predator and prey. Also, many people are frightened of spiders, ensuring the animals place in a plethora of taboos. Possibly the most well known taboo is that the bite of a tarantula was to cause a fatal condition called tarantism. The condition could only be cured with a wild form of dancing that we now know as the tarantella. And finally, the tarantula has become extremely popular in the exotic pet trade.
Journal Article Review:
This journal article details the discovery of a new species of tarantula, Coremiocnemis Tropix, in Northern Australia. It is particularly interesting because it gives an in depth look at a specific species of tarantula, and because it shows the steps one must take to confirm and document a new species of animal.