Theridion grallator

Taxobox
name = Happyface spider


image_width = 240px
regnum = Animalia
phylum = Arthropoda
classis = Arachnida
ordo = Araneae
subordo = Araneomorphae
familia = Theridiidae
genus = "Theridion"
species = "T. grallator"
binomial = "Theridion grallator"
binomial_authority = Simon, 1900

"Theridion grallator", also known as the "happyface" spider, is a member of the Theridiidae family.

The Hawaiian name is "nananana makakiokinai" (face-patterned spider). The binomial "grallator" is Latin for "stiltwalker", reference to the species' long spindly legs.

Appearance

The spider is about 5mm long overall.

Certain morphs have a pattern uncannily resembling a smiley face or a grinning clown face on their yellow body. Each spider has a unique pattern, and the patterns differ from island to island. Some lack markings altogether.On the island of Maui, the happy types seem to follow simple Mendelian inheritance rules, while on other Hawaiian islands the body inheritance patterns seem to be sex-limited. [http://www.benecke.com/happyface.html] The variation is possibly a kind of camouflage against birds, their only natural enemies of significance, to counteract pattern recognition by predators. As the pattern may change according to what food the spider has eaten (Gillespie, 1989) and as "T. grallator" is very small, hides during the day, and is thus not a significant prey item for any species of predator, it is more likely that the bizarre variety of patterns serves no significant adaptive purpose at all.

Habits

They live beneath the leaves of plants, where they also spin their much reduced webs. The females guard their eggs until they hatch, and catch prey for their young."T. grallator" hunts mainly during the evening.

Distribution

"T. grallator" is endemic to Ookinaahu, Molokaokinai, Maui and the Big Island in rainforests at elevations of 300 to 2,000 meters.

References

* Gillespie, R. G. (1989): Diet-induced color change in the Hawaiian happy-face spider "Theridion grallator" (Araneae,Theridiidae). "Journal of Arachnology" 17(2): 171-177. [http://www.americanarachnology.org/JoA_free/JoA_v17_n2/JoA_v17_p171.pdf PDF fulltext]
* Gillespie, R. G. & Tabashink, B. E. (1989) What makes a happy face? Determination of colour pattern in the Hawaiian happy face spider "Theridion grallator" (Araneae,Theridiidae). "Heredity" 62: 355-363.

External links

* [http://starbulletin.com/96/09/17/features/spider.gifImage of "T. grallator"]
* [http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_41 Different morphs]
* [http://www.hear.org/starr/hiinsects/images/thumbnails/html/theridion_grallator.htm A Theridion grallator in its nest]