Yellow sac spider
Encyclopedia
Cheiracanthium inclusum, alternately known as the black-footed yellow sac spider or the American yellow sac spider (in order to distinguish it from its Europe
an cousin C. punctorium
), was formerly classified as a true sac spider
(of the family Clubionidae), but now belongs to the long-legged sac spiders (family Miturgidae). It is a rather small pale yellow species that is indigenous to the Americas
and can be found living in the foliage of forests and gardens but also can inhabit human homes. C. inclusum is also one of a handful of spiders found in North America whose bites are generally considered to be medically significant. 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.
The spider relies more on palps, sensory structures just behind the chelicerae on the cephalothorax, to sense its environment.
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.
to humans but rarely produces more than local symptoms. They are believed to produce a high percentage of the spider bites suffered by people, possibly because they wander about when people cannot see well or are asleep, and so they may get squeezed and bite to protect themselves. Bites that occur to farm laborers may occur because spiders hiding in their shelters on leaves may get squeezed.
It has been noted that a large number of bites attributed to the brown recluse spider
may actually be the result of yellow sac spider bites, which possess a cytotoxic venom known to contain several proteolytic enzymes including alkaline phosphatase
, deoxyribonuclease
, esterase
, hyaluronidase
, lipase
, and ribonuclease
. These enzymes can cause localized tissue necrosis
(which may be similar to that caused by a recluse bite), though the symptoms are less severe and do not result in the systemic effects occasionally seen with recluse envenomations.
However, the view that this spider is dangerous to humans has been questioned. A recent study of 20 confirmed yellow sac spider bites revealed no evidence of necrosis; further review of international literature on confirmed bites revealed only a single bite with mild necrotic symptoms.
Although the danger of C. inclusum may be questionable, the spider bite may cause local redness with stinging pain. When it's found immediately wash from the bite site to prevent further venom entering the wound in case of the spider bite. Thoroughly wash the wound with soap and water. Do not use alcohol. Also do not engage in any activity that raises the heart rate. An ice pack may be applied to draw out the venom. Do not squeeze or pick the bite site. It may cause secondary infection or spread the poison to a wider tissue region. If the pain persist for a long period, show it to a doctor for a proper measure.
C. inclusum bites usually occur when the spider is threatened. People might threat C. inclusum without noticing in some incidents. For example, while C. inclusum is hunting during the night time, people may roll over and press the spider accidentally or put on a coat that stayed in the closet over the winter without noticing the spider inside. Also, putting the shoes on while C. inclusum is in there. As the weather cools down, it is more likely for the spider to invade the indoor structures. To prevent the bite from C. inclusum, secure all screens on the windows and doors. Do not stack fire wood near the house. Also, take care of all the house pests such as ants and silverfish that attract spiders.
In March 2011, Mazda
initiated a recall of 65,000 Mazda6 automobiles after webs of this species were found to have clogged fuel system ventilation tubes. It is unclear why the spiders were drawn to build webs inside this particular vehicle, but the problem appeared to be widespread, though rare, across the United States
.
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an cousin C. punctorium
Cheiracanthium punctorium
Cheiracanthium punctorium, one of several species commonly known as the yellow sac spider, is a spider found from central Europe to Central Asia...
), was formerly classified as a true sac spider
Sac spider
The sac spiders of the family Clubionidae have a very confusing taxonomic history. Once this family was a large catch-all taxon for a disparate collection of spiders, similar only in that they had eight eyes arranged in two rows, conical anterior spinnerets that touched and were wandering predators...
(of the family Clubionidae), but now belongs to the long-legged sac spiders (family Miturgidae). It is a rather small pale yellow species that is indigenous to the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
and can be found living in the foliage of forests and gardens but also can inhabit human homes. C. inclusum is also one of a handful of spiders found in North America whose bites are generally considered to be medically significant. 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.
Identification
Like 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 9mm and in males, 4 to 8mm. The leg span however can be up to 1 inch with the front pair of legs being longer than the other 3 pairs. Males tend to have a skinnier body and a larger leg span than females. C. inclusum gets its 2 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. In terms of sensory structures, C. inclusum has 8 similarly sized eyes distributed in 2 parallel horizontal rows. However their eyes are thought to be less important structures due to the absence of light during the spider's nocturnal activity.The spider relies more on palps, sensory structures just behind the chelicerae on the cephalothorax, to sense its environment.
Distribution
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.Life cycle
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 lying 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 that produce multiple egg masses build a second egg sac about two weeks after the juvenile spiders disperse. Males tend to mature faster (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. They over-winter mostly as adults or sub-adults.Behavior
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
Ballooning (spider)
Ballooning is a term used for the mechanical kiting that many spiders, especially small species, as well as certain mites and some caterpillars use to disperse through the air. Many small spiders use gossamer or especially fine silk to lift themselves off a surface or use the silk as an anchor in...
through the air.
Human impact
The bite of these spiders is believed to be venomousSpider bite
A spider bite is an injury resulting from the bites of spiders or other closely related arachnids.Spiders are active hunters and rely heavily on their bites to paralyze and kill their prey before consuming it. They also bite in self defense...
to humans but rarely produces more than local symptoms. They are believed to produce a high percentage of the spider bites suffered by people, possibly because they wander about when people cannot see well or are asleep, and so they may get squeezed and bite to protect themselves. Bites that occur to farm laborers may occur because spiders hiding in their shelters on leaves may get squeezed.
It has been noted that a large number of bites attributed to the brown recluse spider
Brown recluse spider
The brown recluse spider or violin spider, Loxosceles reclusa, is a member of the family Sicariidae . The spider has a venomous bite....
may actually be the result of yellow sac spider bites, which possess a cytotoxic venom known to contain several proteolytic enzymes including alkaline phosphatase
Alkaline phosphatase
Alkaline phosphatase is a hydrolase enzyme responsible for removing phosphate groups from many types of molecules, including nucleotides, proteins, and alkaloids. The process of removing the phosphate group is called dephosphorylation...
, deoxyribonuclease
Deoxyribonuclease
A deoxyribonuclease is any enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone. Thus, deoxyribonucleases are one type of nuclease...
, esterase
Esterase
An esterase is a hydrolase enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis.A wide range of different esterases exist that differ in their substrate specificity, their protein structure, and their biological function.- EC classification/list...
, hyaluronidase
Hyaluronidase
The hyaluronidases are a family of enzymes that degrade hyaluronic acid.In humans, there are six associated genes, including HYAL1, HYAL2, HYAL3, and PH-20/SPAM1.-Use as a drug:...
, lipase
Lipase
A lipase is an enzyme that catalyzes the formation or cleavage of fats . Lipases are a subclass of the esterases.Lipases perform essential roles in the digestion, transport and processing of dietary lipids in most, if not all, living organisms...
, and ribonuclease
Ribonuclease
Ribonuclease is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within the EC 2.7 and 3.1 classes of enzymes.-Function:All organisms studied contain...
. These enzymes can cause localized tissue necrosis
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
(which may be similar to that caused by a recluse bite), though the symptoms are less severe and do not result in the systemic effects occasionally seen with recluse envenomations.
However, the view that this spider is dangerous to humans has been questioned. A recent study of 20 confirmed yellow sac spider bites revealed no evidence of necrosis; further review of international literature on confirmed bites revealed only a single bite with mild necrotic symptoms.
Although the danger of C. inclusum may be questionable, the spider bite may cause local redness with stinging pain. When it's found immediately wash from the bite site to prevent further venom entering the wound in case of the spider bite. Thoroughly wash the wound with soap and water. Do not use alcohol. Also do not engage in any activity that raises the heart rate. An ice pack may be applied to draw out the venom. Do not squeeze or pick the bite site. It may cause secondary infection or spread the poison to a wider tissue region. If the pain persist for a long period, show it to a doctor for a proper measure.
C. inclusum bites usually occur when the spider is threatened. People might threat C. inclusum without noticing in some incidents. For example, while C. inclusum is hunting during the night time, people may roll over and press the spider accidentally or put on a coat that stayed in the closet over the winter without noticing the spider inside. Also, putting the shoes on while C. inclusum is in there. As the weather cools down, it is more likely for the spider to invade the indoor structures. To prevent the bite from C. inclusum, secure all screens on the windows and doors. Do not stack fire wood near the house. Also, take care of all the house pests such as ants and silverfish that attract spiders.
In March 2011, Mazda
Mazda
is a Japanese automotive manufacturer based in Fuchū, Aki District, Hiroshima Prefecture, Japan.In 2007, Mazda produced almost 1.3 million vehicles for global sales...
initiated a recall of 65,000 Mazda6 automobiles after webs of this species were found to have clogged fuel system ventilation tubes. It is unclear why the spiders were drawn to build webs inside this particular vehicle, but the problem appeared to be widespread, though rare, across the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
.
External links
- The Nearctic Spider Database
- Photo
- Pictures of C. inclusum (free for noncommercial use)
- U Arkansas - Arthropod Museum Notes by Jeffrey K. Barnes
