Psalmopoeus cambridgei
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Psalmopoeus cambridgei , young female |
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| Psalmopoeus cambridgei | ||||||||||||
| Pocock , 1895 |
Psalmopoeus cambridgei (sometimes called the Trinidad Green Tarantula ) is a web spider from Trinidad . It belongs to the family of tarantulas (Theraphosidae). It is the largest species in the genus Psalmopoeus . Because of its pattern on the abdomen , which is reminiscent of the chevron in uniforms, it is also called Trinidad Chevron Tarantula in English. This species was described by Reginald Innes Pocock in 1895. The species name was chosen in honor of his friend and colleague Frederick Octavius Pickard-Cambridge . It is an arboreal spider and is found in the northern rainforest area of Trinidad. The species is often kept in terrariums and is easy to breed. Offspring are therefore often offered in pet shops. A bite from this spider is very painful due to the effects of its venom.
Habitat and way of life
The spiders are found in the forests of the northern Northern Range in Trinidad. There are temperatures around 30 ° C all year round. The humidity is very high and only drops slightly to 75% during a dry phase from December to May. It lives in knotholes, in tree crevices or in the spaces between larger folded leaves, which it lines with spider silk to form an approx. 20 centimeter long tube. This species of spider is not picky about the choice of housing. Peter Klaas reports that a large number has already been found in boreholes for a road construction project in Trinidad. During a Canadian expedition in December 2004, a specimen was found as a cultural follower in a crumbling building. In a more natural area there are some specimens on shaded road slopes with a loamy and stony subsoil. They often coexist with other mygalomorphic spiders, such as funnel spiders . Psalmopoeus cambridgei does not dig caves in these places, but instead weaves its living tubes camouflaged in the vegetation close to the surface.
In the evening and night hours, the animals sit in front of the living tubes and wait for prey . They often place their legs parallel to the body's longitudinal axis, very likely to appear smaller and to blend in visually with the ground. In the event of imminent danger or strong vibrations, they very quickly retreat into the protective living tubes. If retreat is not possible, they run very quickly down the tree trunk to disappear into the undergrowth, or they drop and flee quickly into the next hiding place. During the day the animals hide in the living tubes.
Mating is usually peaceful. After successfully mating , the female produces a cocoon that contains between 80 and 150 eggs. Sometimes the female hangs the cocoon on the wall of the living tube with a thread. The larvae are about five millimeters long. This is relatively long compared to the larvae of other tarantula species. The young hatch after about eight months and, given enough food, grow very quickly and reach a leg span of up to four centimeters within two months.
Adult males live a maximum of three years after moulting. Adult females, on the other hand, have a remaining life expectancy of around twelve years.
features
The animals in the wild have a greenish tinge, which the specimens in captivity (terrarium keeping) usually lack. The female becomes six to seven centimeters long (from the biting claws to the spinnerets). With leg spans of up to 15 centimeters, it is the largest species within the genus Psalmopoeus to date . The top of the body and extremities is covered with gray, yellowish hair. The lines on the limbs are made up of lighter, whitish hair. The spiders have a reddish to brownish spot on the top of the tarsi and a stripe of the same color on the metatarsi. The surface of the carapace and the coxa is colored chocolate brown and has a greenish sheen depending on the incidence of light. The long hair on the limbs is colored yellow and the tufts of hair on the underside of the biting claws are blood red in color. There is a dark band on top of the opisthosoma. Transverse strips arise from this band. There are no stinging hairs on the opisthosoma , as is otherwise found in many species of tarantulas on the American double continent. The tarsi and metatarsi are wide and thus enable an arboreal (tree-dwelling) way of life.
The male is smaller. It is similar in color to the female, but is more uniformly brownish in color. It looks very much like the male of Psalmopoeus irminia . The pattern on the opisthosoma shows up mainly shortly after the moult and fades over time.
The young animals have a basic black color. The metatarsi are light brown to reddish in color. On the opisthosoma there is a jagged pattern of light brown to reddish areas. The drawing is reminiscent of the adult stage of the related species Psalmopoeus irminia .
The carapace is a little longer than it is wide. It is a little shorter than the total length of the patella and tibia of the fourth pair of legs. The sternum is oval. It is a lot longer than it is wide.
male
female
Young animal in the second skin
Receptaculum seminis of the female
A wild female in Trinidad
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Poison
The effects of the poison psalmotoxin and the vanillotoxins from Psalmopoeus cambridgei on the human body were investigated. Psalmotoxin I consists of 40 amino acids , including six cysteine residues, which give the peptide a very compact and stable basic structure through three disulfide bridges . Three loops, the N terminus and the C terminus , protrude from this basic structure . In terms of its mode of action, the peptide has similarities with capsaicin , an alkaloid that makes chili peppers and related species so hot. It is speculated whether the poison not only has the function of paralyzing or killing prey, but that the effect on pain receptors also represents a defense against predators (larger mammals and birds; generally vertebrates ). Both psalmotoxin and capsaicin activate the TRPV1 receptors of nerve cells, but they probably use different mechanisms. This would explain why psalmotoxin also works against birds, whereas capsaicin does not trigger any irritation in them.
Web links
Psalmopoeus cambridgei in the World Spider Catalog
Individual evidence
- ↑ a b c R. I. Pocock: On a new and natural grouping of some of the oriental genera of Mygalomorphae, with descriptions of new genera and species. In: Ann. Mag. Nat. Hist. 15, No. 6, 1895, pp. 165-184, Pl. X.
- ↑ a b c S. Müller: Tarantula catch on Trinidad and Tobago (West Indies) . Arachnol. Number 10. 1991. pp. 9-11.
- ↑ a b c d e f Peter Klaas: tarantulas: origin, care, species . Eugen Ulmer Verlag , Stuttgart 2003/2007, ISBN 978-3-8001-4660-4 , pp. 109-110
- ↑ Martin Gamache, & Amanda Gollaway: Excursion to Trinidad: Psalmopoeus cambridgei POCOCK, 1895 in the wild . 'in: ARACHNE 11 (3), 2006: 22-26.
- ↑ Hans Werner Auer, Martin Huber, Armin Bochtler: The genus Tapinauchenius Ausserer, 1871 in portrait . In: Arachne 12, No. 2, 2007, p. 15 & p. 23.
- ↑ Graham M. Nicholson: Spider Venom Peptides . In: Abba J. Kastin (Ed.): Handbook of biologically active peptides . Academic Press, 2006, ISBN 978-0-12-369442-3 , pp. 369-380 ( 376 ), OCLC 71846806 (accessed October 14, 2009).
- ↑ J. Siemens et al .: Spider toxins activate the capsaicin receptor to produce inflammatory pain. In: Nature 444, 2006, pp. 208-212, doi: 10.1038 / nature05285 .