Visual communication is used during courtship. Upon contact with each other, the spiders vibrate the web. Males use a rhythmic pattern when vibrating the web during courtship. These spiders also move up and down their silk lines to show a reaction to other creatures. It is likely that there are patterns for this also.
Communication Channels: visual ; tactile
Other Communication Modes: vibrations
Perception Channels: visual ; tactile ; vibrations
This species is plentiful throughout the western hemisphere.
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: no special status
These spiders can bite, but they are not of much harm to humans. Humans can be bothered by the species' spines, which may cause a puncture in skin if touched in the wrong place. So, although they eat insects in orchards, which is beneficial, they become a pest during harvest time.
Negative Impacts: injures humans (bites or stings)
This tiny spider is an interesting species for study and research. Additionally, the fact that G. cancriformis preys on small insects in citrus groves helps farmers to control pests. Since there is clinal variation in these animals in the different areas where they are found, researchers are able to study genetic variation, clines, and adaptations to a specific environments.
Positive Impacts: research and education; controls pest population
In nature, this species preys upon many small insect pests that are present in crops and suburban areas. It helps to control overpopulation of such insects.
Females build webs that they use to capture prey. A female sits facing down in her web, awaiting her prey on the central disk. When a small insect flies into the web, she moves toward it, then snaps the radii on either side of the insect. In order to secure the prey, the spider snaps more of the web around the area, then rushes toward the prey in order to determine its exact location and bite it before carrying it back to the central disk where she feeds.
To carry a prey item back to the central disk, the female either climbs back up the web with her food, or swings down a drag line then climbs up to her resting area. If the prey is smaller than the spider, she will just paralyze it, carry it to her spot, and eat it without wrapping it up. If the prey item is larger than the spider, it requires wrapping before being carried to the central disk.
Sometimes several prey insects become caught in the web at the same time, so that the spider must find and paralyze them all. If it is not necessary to carry them away to eat them, the spider may just feed on them where they are, then come back to them as she pleases.
Gasteracanta cancriformis feeds upon the liquified insides of her prey. Deliquified carcasses are discarded from the web and are easily recognized in their mummified state.
Foods eaten: drosophilids, whiteflies, beetles, moths, other small fly species (none appear to have been rejected).
Animal Foods: body fluids; insects; terrestrial non-insect arthropods
Primary Diet: carnivore (Insectivore )
Gasteracantha cancriformis is found in many parts of the world. It is found across the southern part of the United States from California to Florida, as well as in Central America, Jamaica, and Cuba.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Spiny crablike orb weavers, G. cancriformis, live in woodland edges and shrubby gardens. Many of the studies on this spider have taken place in citrus groves in Florida. They frequently live in trees or around trees in shrubs.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: forest ; rainforest ; scrub forest
Other Habitat Features: suburban ; agricultural
This species of spider does not live very long. In fact, the lifespan only lasts until reproduction, which usually takes place the spring following the winter when they hatched. Females die after producing an egg mass, and males die six days after a complete cycle of sperm induction to the female.
Typical lifespan
Status: wild: 1 (high) years.
Gasteracantha cancriformis showed marked sexual dimorphism in size. Females are 5 to 9 mm in length and 10 to 13 mm in width. Males are 2 to 3 mm long and a small amount shorter in width. Six abdominal spines are present in all morphs, but color and shape show geographic variation. Most individuals have white spots on the underside of the abdomen, but the color of the back and spines may be red, orange or yellow. Also, a small number of spiders have colored legs.
Range length: 2 to 9 mm.
Other Physical Features: ectothermic ; bilateral symmetry ; polymorphic
Sexual Dimorphism: female larger
Crablike spiny orb weavers probably received this common name because of the spines on their backs. These spines may have an anti-predator function. These spiders are also very small, making it hard for a predator to see them and attack them. The spider eggs are often attacked by parasitoid wasps and flies.
Known Predators:
The only known observations of mating behavior occured in a laboratory environment where there was only one female and one male to work with. It is assumed that the mating system in nature is similar to, if not the same as, that observed in the laboratory environment. However, scientists are not sure whether these animals are monogamous or polygamous.
Laboratory studies of mating behavior show that males visit female webs, and use a 4-tap rhythmical-pattern drumming on the silk of the web. After several cautious approaches, males approach females, become strapped down with silk from the female, and copulate. Mating may take 35 minutes or more. After mating, the male remains on the female's web. Mating may occur repeatedly.
While facing down near the center of her web, the female produces an egg sac with 100 to 260 eggs. She deposits the sac on the underside of leaves near the nest, then dies. The eggs must hatch and survive without parental care over the winter, then spiderlings disperse in the spring when they are able to spin webs and produce eggs (females) or fertilize eggs (males) on their own. Both males and females reach maturity within 2 to 5 weeks of age.
Breeding season: Breeding occurs during winter.
Range number of offspring: 100 to 260.
Range age at sexual or reproductive maturity (female): 2 to 5 weeks.
Range age at sexual or reproductive maturity (male): 2 to 5 weeks.
Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External )
All parental care in crablike orb weavers occurs before the young hatch. After the female lays an egg mass, she dies. The eggs are left to hatch and the spiderlings to disperse. In order to protect and feed the young in their egg and larval stages, the female constructs an egg case. In nature, the case is constructed on the bottom and sometimes the top of the leaves on trees where the web is located, but not on limbs or trunks of trees. The case is constructed first from an ovate egg sheet made of loosely woven fine threads which are firmly attached to the lower leaf surface with strong attachment disks. The eggs are distributed upward on the platform in a long, ovate mass. The female covers the egg mass with a loose, spongy, tangled mass of yellow and white threads, fastened with the same type of disks used before. Another covering is made when the female moves along the mass, loosely covering it with several dozen coarse, rigid, dark green threads. These threads form a distinct longitudinal line on the case. The final cover is a net-like canopy, spun over the mass and attached to a leaf. Hatched spiderlings take a few days to learn how to move correctly, and under undisturbed, natural conditions do not disperse from the case for 2 to 5 weeks.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)
Gasteracantha cancriformis[2] (spinybacked orbweaver) is a species of orb-weaver spider (family Araneidae). It is widely distributed in the New World.[1]
The genus name Gasteracantha derives from the Greek words γαστήρ (gaster, "belly") and ἄκανθα (acantha, "thorn"), while the specific epithet cancriformis derives from the Latin words cancer ("crab") and forma ("shape, form, appearance").
Females are 5–9 mm (0.20–0.35 in) long and 10–13 mm (0.39–0.51 in) wide. The six abdominal spine-like projections on the abdomen are characteristic. The carapace, legs, and underside are black with white spots under the abdomen. Variations occur in the colour of the upperside of the abdomen - a white or yellow colour with both featuring black spots. A white upper side can have either red or black spines while a yellow upperside can only have black ones. Like with many other spiders, males are much smaller (2 to 3 mm long) and longer than wide. All morphs have six abdominal spines.[3][4] They are similar to the females in colour, but have a gray abdomen with white spots and the spines are reduced to four or five stubby projections.
This species of spider does not live very long. In fact, the lifespan lasts only until reproduction, which usually takes place in the spring following the winter when they hatched. Females die after producing an egg mass, and males die six days after a complete cycle of sperm induction to the female.
G. cancriformis is native to North America, Central America, the Caribbean and South America.[1] It has been introduced elsewhere, including Hawaii. It prefers living around the edge of woodland and shrubby gardens. Many studies about G. cancriformis are performed in citrus groves in Florida.[1][5]
G. cancriformis is seen to coexist within and on the edges of the colonies of other colonial orb-weaver spiders, mainly Metepeira incrassata. M. incrassata is known to form large colonies ranging from few hundreds to few thousands of spiders, and their colonies often accommodate other species of orb-weavers including G. cancriformis.[6]
G. cancriformis has two subspecies, G. c. cancriformis and G. c. gertschi.[7]
Eating a butterfly
Ventral view, with spinneret visible
In Miami
In Miami Lakes
In Ecuador
In Novo Hamburgo (southern Brazilian population), with focus on the web
Mating in the Summer
On a tufted web in Houston, Texas
Color variation, near Houston
Underside of orange specimen, showing spinner and thread. For scale, band in background is 6 mm wide. Near Houston
_-_ventral_view.jpg)
Ventral view, in North Carolina
Gasteracantha cancriformis (spinybacked orbweaver) is a species of orb-weaver spider (family Araneidae). It is widely distributed in the New World.
The genus name Gasteracantha derives from the Greek words γαστήρ (gaster, "belly") and ἄκανθα (acantha, "thorn"), while the specific epithet cancriformis derives from the Latin words cancer ("crab") and forma ("shape, form, appearance").
