Giant fishing spider

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Giant fishing spider
Giant fishing spider (Ancylometes rufus), male

Giant fishing spider ( Ancylometes rufus ), male

Systematics
Order : Spiders (Araneae)
Subordination : Real spiders (Araneomorphae)
Partial order : Entelegynae
Family : Comb spiders (Ctenidae)
Genre : Ancylometes
Type : Giant fishing spider
Scientific name
Ancylometes rufus
( Walckenaer , 1837)

The giant fishing spider ( Ancylometes rufus ) is a spider belonging to the family of comb spiders (Ctenidae). Like the others of the genus Ancylometes , this species, which is widespread in northern South America , has a remarkable and very aquatic way of life.

features

Detail of a male

The female of the giant fishing spider reaches a body length of 40 to 50 millimeters and the male one of 25 to 30 millimeters. The leg span of the species can be 100 to 200 millimeters. This makes the giant fishing spider one of the largest species of the genus Ancylometes and one of the largest among the real spiders (Araneomorphae). A thick pad of hair covers the entire body and enables the giant fishing spider to move on and under water. At the same time, air can be stored in the coat. The hair can also serve as sensilla (sensory hair). The eight comparatively small and reasonably well developed eyes are arranged in two rows one above the other. As with other spiders, the giant fishing spider also has a noticeable sexual dimorphism (difference between the two sexes).

male

The prosoma (front body) of the male takes up 18.8 millimeters of body length and is 16 millimeters wide. The clypeus , a narrow section between the front pair of eyes and the edge of the carapace (back shield), is 1.5 millimeters wide. In the male, the prosoma has a dark brown basic color and broad, cream-colored to white longitudinal bands on the sides. The legs and the opisthosoma (abdomen) are dark brown on top, but lighter on the ventral side. The femora (thighs) and the patellae (limbs between the femora and tibia (greaves)) have white points on the dorsal side and the femora also have white lines laterally. The existing in the males of many spiders Tibial apophyses ( chitinisterte extensions) to the pedipalpi (converted extremities) are bent in a curved manner in the male of the giant fishing spider on the ventral side and have a black color on on the lateral side. The emboli (components of the bulbi, or male genital organs, which serve to transmit semen) have a wide base and are each flanked by a triangular membrane flap that runs in a semicircle and ends in a thread-like manner under the tip of the pelvis, with the middle part in one wide and wing-like conductor is embedded. Opposite this ladder is a slightly curved, relatively long, hammer-like median apophysis. The chelicerae (jaw claws) are provided with three promarginal and four retromarginal teeth. The promarginal teeth are smaller. The area between the lower row of eyes to the base of the chelicerene is also colored white.

female

The female also has a dark brown basic color. However, this is lighter than the male and it is otherwise drawn with much less contrast. His prosoma is 18.3 millimeters long and 15.2 millimeters wide. The clypeus is 1.1 millimeters long here. Both the prosoma and the opisthosoma are colored uniformly brown. The legs are mottled gray and the chelicerae almost resemble those of the male. However, like that of the legs, their coloring appears washed out by dark or yellow irregular spots. The epigyne (female genital organ) consists of a flat central plate, which is shaped like a trigon, with rounded edges and otherwise no attachment. The openings of the Egipyne are anteriolateral and the copulation ducts are sigmoidal. The copulatory ducts end ventrally in the circular spermatheks (fertilization organs ), which are very close together.

Similar species

Females of the fishing spider ( Ancylometes bogotensis )

Several species similar to the giant fishing spider are in the genus Ancylometes . An example is the fishing spider ( Ancylometes bogotensis ), which is something, however, as other species of the genus smaller than the giant fishing spider. This also has a slightly lighter basic color and the prosoma of the male has a much narrower border. The waterhunting spider does not have any other white color. Like other species of the genus, the giant fishing spider resembles species from the genus of bank hunters ( Dolomedes ) within the family of predatory spiders (Pisauridae), which also belong to the superfamily of the Lycosoidea and have a similar way of life.

Occurrence

Rainforest waters like this one in the Departamento del Caquetá in Colombia form the habitats of the giant fishing spider

The giant fishing spider is found in the Amazon basin and along the Atlantic coast of Brazil and inhabits the rainforests there . According to their way of life, the species, like the others of the same genus, can often be found there near ponds or small streams or on the banks of larger rivers.

Threat and protection

No information is available about possible threats to the population of the giant fishing spider, as the species is not managed by the IUCN .

Way of life

Like the other species of the genus Ancylometes, the giant fishing spider is bound to bodies of water and accordingly spends most of its life there. Likewise, they often stay on the surface of bodies of water and row there. If necessary, for example to catch prey or when encountering predators (predators), the giant fishing spider can also dive completely under water and can stay there for up to an hour thanks to the oxygen stored in its thick hair. In the event of a threat, for example, the spider stays under water longer and finds a hold on the bottom of the water or vegetation.

Hunting behavior and catch of prey

Male with captured frog

The hunting method of the giant fishing spider is identical to that of other species of the genus and thus the waterhunting spider can hunt both on land and in the water. She uses her sense of sight and vibration both on land and on water. This is conveyed to her through the sensilla. Like other comb spiders, it does not create a spider web for catching purposes, but hunts as an ambush hunter and remains largely motionless. As soon as a prey animal comes within range and can be located, it snaps towards it and holds it tight. The hunting method is identical both on land and under water, although the giant fishing spider, like river bank hunters of the genus Dolomedes , can also dive under water to catch prey. In addition to other invertebrates , the prey scheme also includes smaller vertebrates such as reptiles , amphibians (including tadpoles ) including fish of the appropriate size.

Reproduction

The reproductive behavior of the giant fishing spider is identical to the other species of the genus. A sexually mature female lays out spider threads with pheromones , with which it can be found by males. If this is the case, the male carefully approaches the female. After a light touch for the purpose of courtship , the female remains motionless and the male climbs on his partner and ties her up with spider silk. The male has spun the female, who does not offer any resistance, within a few seconds. As is usual with free-hunted spiders, the male now climbs on top of the female and the actual mating act begins as the male alternately introduces his bulbi (male genital organs) into the epigyne (female genital organs) of the female. This process takes less than a minute and the male then moves away from the female, which in the meantime frees itself from the male's web.

The food requirement of the now mated female increases sharply due to the maturing eggs. After about a week, it will make an egg cocoon that contains 100 to 200 eggs. This is comparatively large and is sprinkled with a liquid secreted by the female, which makes the cocoon waterproof and is supposed to protect it from fungal attack. The egg cocoon is then attached to the chelicerae (jaw claws) and carried by the female. Similar to the hunting spiders (Pisauridae), after about a month, shortly before the young animals hatch, a large web is created slightly above the ground and the cocoon is placed in it. As with the predatory spiders, both the cocoon and the young animals, which are around two millimeters in size, are guarded by the female for some time. These are distributed in the web and experience their first molt within two days. After a few more days, the young animals become independent and leave the web. They grow up in a period from ten months to a full year. Overall, a mated female can make up to three cocoons and thus also have the brood care typical of the species of the genus. Females of the species reach a lifespan of two or more years, while males only live 14 to 16 months.

Systematics

The giant fishing spider was renamed more and more, so it was initially counted to the hunting spiders (Pisauridae), but in 1967 together with its genus under Pekka T. Lehtinen, it was added to the comb spiders (Ctenidae). By Rita Delia Schiapelli and Berta S. Gerschman de Pikelin took place in 1970 a renewed conversion to the hunting spiders, then a second time from 2003 Silva Dávila was revised. In the first description of the giant fishing spider carried out in 1837, it was given the name Ctenus rufus by Charles Athanase Walckenaer . The current name Ancylometes rufus has been used since 2003. Meanwhile used synonyms of the species are:

  • Ctenus fuscus Walckenaer , 1837
  • Ctenus giganteus Taczanowski , 1874
  • Leptoctenus tenkatei Hasselt , 1888
  • Lycoctenus brunneus F. O. Pickard-Cambridge , 1897
  • Lycoctenus gigas F. O. Pickard-Cambridge , 1897
  • Lycoctenus demerarensis F. O. Pickard-Cambridge , 1897
  • Ancylometes gigas Simon , 1898
  • Lycoctenus saraensis Beach , 1909
  • Ancylometes vulpes Petrunkevitch , 1910
  • Ctenus tenkatei Petrunkevitch , 1911
  • Lycoctenus paraensis beach , 1916
  • Ancylometes pindareensis de Mello-Leitão , 1921
  • Ctenus juruensis Mello-Leitão , 1922
  • Ctenus striolatus Mello-Leitão , 1922
  • Ctenus xerophilus Mello-Leitão , 1936
  • Lycoctenus titanus Caporiacco , 1947

gallery

  • Rear view of a male

  • Closer view of the male with the captured frog

Individual evidence

  1. ↑ a b c d e f g h Ancylometes rufus (Walckenaer, 1837) from Isopoda (archived) , accessed on March 16, 2020.
  2. ↑ a b c d Ancylometes rufus (Walckenaer, 1837) at the State Museum for Natural History Karlsruhe , accessed on March 16, 2020.
  3. ↑ Ancylometes (Bertkau, 1880) at the State Museum for Natural History Karlsruhe , accessed on March 16, 2020.
  4. ↑ Ancylometes rufus (Walckenaer, 1837) at Global Biodiversity Information Facility , accessed on March 16, 2020.
  5. ↑ Ancylometes (Bertkau, 1880) in the WSC World Spider Catalog , accessed on 16 March 2020th
  6. ↑ Ancylometes rufus (Walckenaer, 1837) in the WSC World Spider Catalog , accessed on March 16, 2020.

literature

Web links

Commons : Giant Fishing Spider  - Collection of images, videos and audio files