TIGER SPIDER: CHARACTERISTICS, HABITAT, FEEDING, REPRODUCTION - BIOLOGY - 2025

The tiger spider (Scytodes globula) is a spider of the suborder Araneomorphae of the Scytodidae family. They are also known as "spitting" spiders because, as a hunting method, they "spit" a sticky substance that directly affects the mobility of their prey.

Like other scythoid species, the tiger spider is strongly associated with the human environment, being considered a synanthropic species. Their activity is preferably nocturnal, so it is difficult to locate them during the day.

Tiger Spider Scytodes globula By Katzider

S. globula uses its front legs asymmetrically during prey capture and immobilization activities. This characteristic indicates a certain degree of laterality of behavior in arachnids and an asymmetric use of the limbs.

Many observational experiments both in nature and in laboratories indicate that this species of spider uses legs I and II on the left side more often than on the right.

Due to this, there is a more frequent loss of the legs on the left side either due to interaction with prey (some of which may be potential predators) or as a consequence of predators as a defense method by autotomy.

General characteristics

Dorsal view of the cephalothorax By BioVipah

The tiger spider shows a high degree of tolerance with members of the same species, so it is common to register several specimens that are close to each other. In their foraging activities, the initial catalyst to initiate prey capture is direct contact.

S. globula can be distinguished from other species with which it lives in sympatry by having a uniform brown abdomen with scattered dark markings. The legs and pedipalps have a brown color with dark bands.

The plunger in males is markedly curved with a distal denticulation originating from the base of the plunger. Females have crescent-shaped crest excavations on their external genitalia that are absent in species such as Scytodes univitatta.

The first two pairs of legs, like other similar species of spiders, are characterized by being longer and possessing greater coverage of mechanoreceptors and chemoreceptors than the third and fourth pairs.

Taxonomy

The genus Scytodes has around 173 species worldwide, of which 42 have a neotropical distribution. Many of the species present in some countries such as Brazil have been reassessed and considered synonymy with more widely spread species such as S. globula, S. univitatta and S. longipes.

Species such as Scytodes maculata, S. annulata, S. scholaris, and S. aguapeyanus are currently synonymous with S. globula.

Habitat and distribution

Tiger spider observed in a human settlement By BioVipah

The tiger spider is widely distributed in South America, specifically in countries such as Brazil, Chile, Bolivia, Argentina and Uruguay. Based on this, it has been pointed out that S. globula is unique to the south.

This species prefers cold and humid habitats, which is consistent with its wide distribution in the countries mentioned above. Geographical areas with higher temperatures and humidity constitute an important geographical barrier for the species.

In natural ecosystems, it is found in a wide variety of forests and grasslands, either on top of vegetation or under logs, and even at ground level among leaf litter. In addition, it is a species that tolerates human intervention well and can occupy cracks in walls, walls and other human constructions such as shelters and hunting grounds.

Currently, in many of the distribution areas it overlaps with Scytodes univitatta, another more common and widespread species that has been recently introduced in the south, especially in Chilean populations.

Feeding

Their main hunting method is to "sit and wait." This strategy is to stay close to their shelter and wait for a prey to pass close enough or to make contact, to attack and capture it. In general, they can be observed active during the night.

When a potential prey is detected, the spitting spider initially attacks it with a mixture of a viscous substance and poison that it expels through the chelicerae, in a determined zigzag pattern that ends up immobilizing the prey.

After this occurs, a second phase of definitive immobilization begins by using silk and fixing the prey to a substrate to later inoculate its venom and feed on it.

These spiders use only the first and second pair of legs for immobilization activities of the prey. They can consume a wide variety of invertebrates including Lepidoptera, Diptera, Coleoptera, and even other spiders and groups of arachnids such as Opiliones.

Interaction with other spiders

Scytodes globula tends to occupy microhabitats with particular humidity and temperature characteristics that are also used by species of greater medical importance such as those belonging to the genus Loxosceles. On multiple occasions, observations of S. globula have been made preying on Loxosceles laeta specimens.

These observations have indicated a certain tendency of S. globula due to arachnophagia, although it has not been demonstrated as a habitual and corroborated tendency. Generally these interactions can result in the death of one of the two spiders, as L. laeta is also capable of predating S. globula.

In addition, the predation of S. globula on spiders of the genus Loxoceles is interesting as a measure of control of the populations of L. laeta around human settlements affected by the high incidence of loxocelism.

Reproduction

There is little reproduction data available on this species of spider and on the Scytodidae family in general. Females are usually larger than males and sometimes during reproductive events they can kill and feed on them.

The abundance of this species compared to L. laeta indicates that the progeny is usually low for each female. On the other hand, there are few data on juveniles and their presence in the diet of spiders such as recluse has also been indicated.

In other species of the genus Scytodes, females respond to pheromones produced by the male. This determines the selection of the male to reproduce because, through the use of these chemical substances, she transmits information about her reproductive state and general condition.

The female chooses the male in better condition. The choice of the male is correlated with the production of larger and heavier egg sacs, as well as with greater fertility and fecundity in the female.

On occasion, female Scytodes can feed on the egg sac, however, typically they take care of the egg sac by carrying it in their chelicerae or hanging them on their net.

References

1. Ades, C., & Ramires, EN (2002). Asymmetry of leg use during prey handling in the spider Scytodes globula (Scytodidae). Journal of Insect Behavior, 15 (4), 563-570.
2. Alfaro, C., Veloso, C., Torres-ContreraS, H., Solis, R., & Canals, M. (2013). Thermal niche overlap of the corner recluse spider Loxosceles laeta (Araneae; Sicariidae) and its possible predator, the spitting spider Scytodes globula (Scytodidae). Journal of Thermal Biology, 38 (8), 502-507.
3. Brescovit, AD & Rheims, CA (2000). On the synanthropic species of the genus Scytodes Latreille (Araneae, Scytodidae) of Brazil, with synonyms and records of these species in other Neotropical countries. Bulletin of the British Arachnological Society 11: 320-330.
4. Canals, M., & Solís, R. (2013). Is the "tiger" spider, Scytodes globula, an effective predator of the corner spider, Loxosceles laeta? Medical Journal of Chile, 141 (6), 811-813.
5. Carvalho, LA, da Silva Souza, E., & Willemart, RH (2012). Behavioral analysis of the interaction between the spitting spider Scytodes globula (Araneae: Scytodidae) and the harvestman Discocyrtus invalidus (Opiliones: Gonyleptidae). The Journal of Arachnology, 40 (3), 332-338.
6. Koh, TH, Seah, WK, Yap, LMY, & Li, D. (2009). Pheromone-based female mate choice and its effect on reproductive investment in a spitting spider. Behavioral ecology and sociobiology, 63 (6), 923-930.
7. Labarque, FM, & Ramirez, MJ (2012). The placement of the spider genus Periegops and the phylogeny of Scytodoidea (Araneae: Araneomorphae). Zootaxa, 3312 (1).
8. Taucare-Rios, A. (2013). The genus of spiders Scytodes Latreille, 1804 (Araneae: Scytodidae) in Chile: diversity and distribution. Chilean journal of natural history, 86 (1), 103-105.
9. Yap, LMY, Norma-Rashid, Y., Liu, F., Liu, J., & Li, D. (2011). Comparative biology of cave-dwelling spitting spiders (Araneae: Scytodidae): Parental care, cooperative prey-capture, cannibalism, natal dispersal and reproductive behavior. Raffles Bulletin of Zoology, 59 (2).