Real tube spiders

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Real tube spiders
Red tube spider (Eresus kollari), male

Red tube spider ( Eresus kollari ), male

Systematics
Trunk : Arthropod (arthropoda)
Sub-stem : Jawbearers (Chelicerata)
Class : Arachnids (arachnida)
Order : Spiders (Araneae)
Family : Tube spiders (Eresidae)
Genre : Real tube spiders
Scientific name
Eresus
Walckenaer , 1805

The genus of the real tube spiders ( Eresus ) belongs to the family of the tube spiders (Eresidae) within the order of the spiders . The best-known species of this family belong to this genus, including the red tube spider ( Eresus kollari ), the ring-footed tube spider ( Eresus sandaliatus ) and the Greek tube spider ( Eresus walckenaeri ).

Based on the appearance of the male with black dots on a red background, the real tube spiders are called Ladybird spiders (translated as " ladybird spiders").

features

Microscopic image of the spinning glands of a real tube spider

Like all tube spiders, the real tube spiders have a stocky build and short-legged appearance. Prosoma (front body) and opisthosoma (abdomen) have almost identical dimensions, especially in males. A distinctive feature of the real tube spiders is the strongly pronounced sexual dimorphism (difference between the sexes), the females are usually much larger, but the smaller males have a much more striking color. The largest species of the tube spider family and at the same time the largest spider on the European mainland is the Greek tube spider ( Eresus walckenaeri ), whose females can reach a body length of up to 40 millimeters. In most other species of this genus, the females have a body length of about fifteen to twenty and the males one of about ten millimeters. The coloring of the individual species is formed by the colored setae (chitinized hairs). In the case of many species that are similar to one another and share the same habitats, reliable differentiation is only possible through genital morphological characteristics, but even with these there are often only minor differences.

male

Detail of a male of Eresus solitarius

The males have a red color and two or three pairs of black points on the opisthosoma. As with the ladybirds, this color serves as a warning color and is intended to deter predators to which the males are potentially more exposed due to their active search for females. The legs are colored red or black depending on the species and usually have white drawings in the form of rings. The prosoma is predominantly or partially black in color. The emboli (part of the bulbi or male reproductive organs) each have a sclerotized (made of structural proteins) end tooth. In the males of the Central European species, this is separated from the lamellae by a groove.

female

Female of Eresus hermani

The larger females, on the other hand, are almost uniformly black in color. In some species the prosoma and the chelicerae (jaw claws) have individual orange hairs. The epigyne (female sex organ) of the real tube spider consists of a simple pit with two longitudinal seams. The front part is provided with a cornification, in which the openings of the copulation channels are located and this is either laterally or medially curved. The front part of the vulva consists of a loop of massive copulatory ducts. The degree of sclerosis varies depending on the species. The distal part of the vulva is predominantly occupied by the spermatheks (fertilization organs). These are lobed and turned sideways. The fertilization canals are tiny, directed promediodorsally and located at the base of the spermatheks. The shape of the vulva as well as the lobes and the general structure of the vulva can help in determining the species. Adult females who have not been fertilized for a long period of time experience a further moult, which also changes the shape of the epigyne and vulva. The epigyne is then usually larger and provided with a sharp longitudinal rod as well as wider splits, while the vulva is characterized by narrower loops of the copulation ducts. The so-called pre-epigyne in subadult females can be confused with the fully developed sex organs of an adult female. The pre-Egipyne, however, is smaller, far less sclerotized and only slightly wider than the area delimited by the splits. Both the copular canals and the spermatheks have a small and simple structure.

Species similar to the real tube spiders

The similar species of the genus Stegodyphus , here S. lineatus , which belong to the same family , have similar sexes and no males with a striking coloration.

The species of the real tube spiders can be confused with the distantly similar ones of the genus Stegodyphus , which belongs to the same family. An essential feature is the sexual dimorphism, which does not occur so strongly here (the males of the species of this genus, like the females, are not conspicuously colored). In addition, the fishing nets of the species of the genus Stegodyphus are much more conspicuous than at least some of the real tube spiders.

Occurrence

A male of a tube spider near the Albanian city ​​of Vlora

The species of the real tube spiders are found exclusively in the Old World across Europe , North Africa and Asia . Three of them, the red tube spider ( E. kollari ), E. moravicus and the ring-footed tube spider ( E. sandaliatus ) are also represented in Central Europe . The preferred habitat of many species of the genus are dry and sandy areas, including rocky steppes or south-facing and protected heather slopes.

Threat and protection

Some real tube spiders are threatened due to the decline in their habitats to which they are bound and, especially because of their distinctive character and popularity, the fight for the preservation of the rock steppes they inhabit in Europe is being fought for. In Germany , the red spider ( E. kollari ) and the ring-footed tube spider ( E. sandaliatus ), the only species of the genus found here, are endangered and enjoy special protection.

Way of life

Free running female of Eresus moravicus

The real tube spiders, like all tube spiders (Eresidae), create spider webs for the purpose of catching prey , which are made of a net carpet with cribellate (crinkle-like) catch threads on one side and on the other in a five to ten centimeters dug into the ground and which gives the family its name ends, which serves as the spider's abode. These extremely effective nets also make it possible to capture large and well-fortified prey, such as ground beetles . The remaining chitin skeletons of eaten prey animals are deposited not far from the net tubes. The red ( E. kollari ) and the ring-footed tube spider ( E. sandaliatus ) occasionally have a large number of nets from several specimens of the same species, all of which occur close together in the same location.

Phenology and reproduction

Subadult female of the ring-footed tube spider ( E. sandaliatus )

The phenology (period of activity) and the reproductive behavior vary in the different species, but many multiply in summer. The males look for the nets of their own females. Their conspicuous coloring serves to protect them from predators (predators). If they feel threatened, they raise the colored opisthosoma and make trembling movements. In the last resort they can also bite (see chapter “ Toxicity and bite accidents ”). Some time after mating , the mated female creates an egg cocoon , which it holds against the sun during the day to warm it up and deposits in the tube at night. The young spiders themselves remain in the mother's tube after hatching and can be fed from mouth to mouth. Some time after hatching, the mother dies, which has presumably been dissolved from within by digestive enzymes and serves as food for the young animals. These then remain in the web of their former mother over the winter and then become independent in the following spring. During this time, the young spiders can molt up to six. Depending on the species, the male becomes sexually mature in spring or autumn. The females can live to be up to four years old and usually do not leave their living tubes.

Real tube spiders and humans

The real tube spiders gain a certain popularity due to the appearance of the males which is characteristic of spiders, which is why their protective measures are taken to preserve their dwindling habitats precisely because of species of this genus (see chapter " Threat and protection ").

Terrariums

Some species, such as the Greek tube spider ( Eresus walckenaeri ) are occasionally kept as pets in the field of terraristics . Here, too, the males are particularly in demand. For many keepers, the habitual way of life typical of web-building spiders (except for sexually mature males) is often viewed positively, as it enables them to be kept in comparatively small containers. The danger emanating from tube spiders is also not really high (see chapter “ Toxicity and bite accidents ”). It has to be considered that you need a burrowable underground or provide a prefabricated tube so that the spider can set up a safety net according to its way of life.

Toxicity and bite accidents

Threatening male of the red tube spider ( E. kollari )

Bites from some real tube spiders have been reported, but medically relevant consequences do not usually occur. Symptoms mentioned are pain that radiates to the armpit, a feverish feeling and an increased heartbeat. If you bite your finger, the pain reaches your armpit. These symptoms go away after an hour or two. However, a severe headache can last for several days and the bite wound may remain tender for a few days.

Systematics

The genus of the real tube spiders was first described in 1805 by Charles Athanase Walckenaer and received no synonyms or changes. The genus had only one species when it was first described , namely Eresus cinnaberinus . It currently comprises 16 species (21 with subspecies):

As of February 25, 2020

Individual evidence

  1. ↑ a b c d e f M. Řezáč, S. Pekár, J. Johannesen: Taxonomic review and phylogenetic analysis of central European Eresus species (Araneae: Eresidae). In: Zoologica Scripta. Volume 37, No. 3, 2008, pp. 263-287 ( online [accessed February 24, 2020]).
  2. ↑ a b c Eresidae (CL Koch, 1845) in "Spinnen van Noordwest-Europa" , accessed on February 24, 2020.
  3. ↑ a b c d Heiko Bellmann: The cosmos spider guide. Over 400 species in Europe. 2nd Edition. Kosmos Naturführer, Kosmos (Franckh-Kosmos), 2016, ISBN 978-3-440-14895-2 , p. 64.
  4. ↑ Eresus (Walckenaer, 1805) at spiders.hxnetz.de , accessed on March 12, 2020.
  5. ↑ Eresus (Walckenaer, 1805) in the WSC World Spider Catalog , accessed February 24, 2020.

literature

  • M. Řezáč, S. Pekár, J. Johannesen: Taxonomic review and phylogenetic analysis of central European Eresus species (Araneae: Eresidae). In: Zoologica Scripta. Volume 37, No. 3, 2008, pp. 263-287 ( online ).
  • Heiko Bellmann: The cosmos spider guide. Over 400 species in Europe. 2nd Edition. Kosmos Naturführer, Kosmos (Franckh-Kosmos), 2016, ISBN 978-3-440-14895-2 .

Web links

Commons : Real tube spiders ( Eresus )  - Collection of images, videos and audio files