Biodiversity of Cyprus by NGO Protection of the Natural Heritage and the Biodiversity of Cyprus: Spiders

Wednesday, 11 October 2023

Ground spiders comprise Gnaphosidae, the seventh largest spider family with over 2,000 described species in over 100 genera distributed worldwide. There are 105 species known to central Europe, and common genera include Gnaphosa, Drassodes, Micaria, Cesonia, Zelotes and many others. They are closely related to Clubionidae. At present, no ground spiders are known to be seriously venomous to humans.

Description

Generally, ground spiders are characterized by having barrel-shaped anterior spinnerets that are one spinneret diameter apart. The main exception to this rule is found in the ant-mimicking genus Micaria. Another characteristic is an indentation in the endites (paired mouthparts anterior and lateral to the labium, or lip). All ground spiders lack a prey-capture web and generally run prey down on the surface. They hunt at night and spend the day in a silken retreat. The genitalia are diverse and are a good model for studying the evolution of genitalia because of their peculiar copulatory mechanism. The thick-walled egg sacs are guarded by the mother until the spiderlings hatch.

Hunting behavior

Ground spiders hunt by active foraging, chasing down and subduing individual prey items. They are adapted to hunting large and potentially dangerous prey, including other spiders, which they subdue by using their silk. When hunting, ground spiders produce thick, gluey silk from their enlarged spinnerets and attempt to use it to entangle their prey in swathing attacks, often applying their webbing to their prey's legs and mouths. By immobilizing potential prey in this manner, ground spiders can subdue proportionally large creatures while reducing risk of injury to themselves from their prey's attempts to fight back. From https://en.wikipedia.org/wiki/Ground_spider

Photo Geri 16/4/2013 by George Konstantinou

Sunday, 11 June 2023

Tropical tent-web spider - Cyrtophora citricola (Forskål, 1775) - Cyprus

Cyrtophora citricola, also known as the tropical tent-web spider, is an orb-weaver spider in the family Araneidae. It is found in Asia, Africa, Australia, Costa Rica, Hispaniola, Colombia, Cyprus and Southern Europe and in 2000, it was discovered in Florida. C. citricola differs from many of its close relatives due its ability to live in a wide variety of environments. In North America and South America, the spider has caused extensive damage to agricultural operations.

C. citricola is in the orb web spider family, but its orb webs are considered atypical. They have a thick silk strand barrier above the orb and a thinner barrier below the orb. This gives the webs a horizontal mesh-like appearance. The spider has developed distinct and specific prey-capturing techniques using its unconventional webs. The prey flies into the upper mesh layer of the web and is deflected into the orb web. The spider then collects and stores the prey in its web. The difference in C. citricola's web silk stems from physiological variations in its spinning apparatuses, as compared to other closely related species. Its webs are non-adhesive and do not require daily respinning.

This spider is one of the few species to exhibit a variable level of sociality. C. citricola can be seen in colonies, which may have arisen due to reduced predation. Within these colonies, each spider has its own web that is linked to other spiders through communal webbing. The spider webs are often built in large matrices next to one another and can span entire trees. The spider usually peacefully coexists with other spiders in the colony. However, at times the spider may have to ward off other spiders in the colony that may try and claim its web.

C. citricola is nocturnal, only performing necessary tasks during the day. During the day, it remains idle and tries to stay out of sight from predators. Most of its foraging and prey capture happen at night.

C. citricola's color and size can vary greatly. Many spiders sport a black and white pattern while others are brown. Males often appear black. Male and female spiders have a sexual dimorphism. The body length in females normally reaches 10 millimetres (0.39 in), while males are only 3 millimetres (0.12 in) long.

From Wikipedia, the free encyclopedia

Photos Agios Sozomenos 19/11/2022 by George Konstantinou