Black-footed yellow sac spider, American yellow sac spider
Cheiracanthium inclusum, alternately known as the black-footed yellow sac spider or the American yellow sac spider (in order to distinguish it from its European cousin C. punctorium), was formerly classified as a true sac spider (of the family Clubionidae), and then placed in the family Miturgidae, but now belongs to family Cheiracanthiidae. It is a rather small pale yellow species that is indigenous to the Americas. It is often found living in the foliage of forests and gardens but also can inhabit human homes. Despite common beliefs of necrosis, Cheiracanthium bites cause only localized swelling. C. inclusum is closely related to Cheiracanthium mildei, an introduced species native to Europe which is similar in appearance and natural history and can also be found in North American homes.
No
NocturnalNocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal",...
Ca
CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
In
InsectivoresAn insectivore is a carnivorous plant or animal that eats insects. An alternative term is entomophage, which also refers to the human practice of e...
Te
TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Ov
OviparousOviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Ar
ArborealArboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some anima...
Fo
FossorialA fossorial animal is one adapted to digging which lives primarily but not solely, underground. Some examples are badgers, naked mole-rats, clams, ...
Pr
PrecocialPrecocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
Cu
CursorialA cursorial organism is one that is adapted specifically to run. An animal can be considered cursorial if it has the ability to run fast (e.g. chee...
Mo
MonogamyMonogamy is a form of relationship in which both the male and the female has only one partner. This pair may cohabitate in an area or territory for...
So
SolitaryC
starts withLike all spiders, C. inclusum has two body segments: a cephalothorax (fused head and thorax) and an abdomen. In females, the body measures between 5 and 9 mm and in males, 4 to 8 mm. The leg span however can be up to 1 inch (2.5 cm) with the front pair of legs being longer than the other 3 pairs. Males tend to have a narrower body and a larger leg span than females. C. inclusum gets its two common names (yellow sac and black-footed spider) from its appearance. It is a pale yellow-beige colour with dark brown markings on its palps, chelicerae (jaws) and on the ends of its tarsi (feet). There is also often an orange-brown stripe running down the top-centre of its abdomen.C. inclusum has 8 similarly sized eyes, distributed in 2 parallel horizontal rows. However, ocular input is of minor importance, due to the absence of light during the spider's nocturnal activities. The spider relies more on its palps, sensory structures just behind the chelicerae, on the prosoma (cephalothorax), to sense its environment.
C. inclusum are native to the New World (North, Central, and South America; and West Indies). This species has also been introduced to Africa and Réunion. They are most often found in trees and shrubs, but may also find shelter in houses and other human-made structures.
Being nocturnal, C. inclusum feed and mate at night. C. inclusum do not make webs to catch prey; instead, they are active predators, feeding on a variety of arthropods such as insects and other spiders. Prey detection may involve detection of mechanical vibrations of the substrate, and vision seems to play an insignificant role. During the day, they retreat in small silk nests similar to those used for reproduction. A new nest, which may be completely closed, open on one side, or open on both sides, is built every day in under 10 minutes.
C. inclusum are known to disperse easily between trees and shrubs. They do this by excreting a long silk thread that gets carried by the wind and sticks to a nearby structure, forming a scaffold between two structures. Alternatively, the spider may stay attached to the thread and balloon through the air. These spiders are infamous for their vertical traveling attached to a silk string, which they use in order to both catch airborne prey, and keep out of reach of other predators, such as larger spiders, centipedes or ants.
Females of C. inclusum mate only once, and produce their first egg mass about 14 days after mating. Two sets of eggs are usually produced, but this can range anywhere from 1 to 5. Egg masses generally contain 17 to 85 eggs, although as many as 112 eggs have been reported in a single egg mass. Egg laying generally occurs during the months of June and July; during this period, females lay their eggs in small (2 cm) silk tubes and enclose themselves with the eggs, protecting them from predators. Females stay with the eggs and juvenile spiders for about 17 days – until their first complete molt. Females which produce additional egg masses construct a second egg sac about two weeks after the juvenile spiders disperse. Males tend to become sexually mature earlier (119 days on average) than females (134 days on average), but time to maturity can range from 65 to 273 days, depending on a number of factors, such as temperature, humidity and photoperiod. C. inclusum spiders normally over-winter as adults or sub-adults.
