''Argiope appensa'', also referred to as the Hawaiian garden spider or banana spider, is an orb-weaving

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

belonging to the family Araneidae.

Distribution and habitat

This species occurs on several islands in the western

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...

, in

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

and from

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the nort ...

, Australia, New Caledonia,

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. It has been introduced to all main islands of

. It inhabits a wide variety of habitats, from coasts to upland forests. During the rainy season from June to November, this species is common in sunny edge areas, such as along roadsides and cultivated area.

Description

This species shows an evident

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

. The strikingly black and yellow females are long, including legs, while the brown males reach only about . On

Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...

, where ''Argiope appensa'' is ubiquitous, it is frequently visited by '' Argyrodes argentatus'', that steals food from the host. Following the

brown tree snake The brown tree snake (''Boiga irregularis''), also known as the brown catsnake, is an arboreal rear-fanged colubrid snake native to eastern and northern coastal Australia, eastern Indonesia (Sulawesi to Papua), Papua New Guinea, and many islands ...

and the subsequent extinction or near-extinction of many of the island's small birds, spider populations on Guam exploded in response to decreasing predation and competition. Nature writer

David Quammen David Quammen (born February 24, 1948) is an American science, nature, and travel writer and the author of fifteen books. His articles have appeared in '' Outside Magazine'', '' National Geographic'', '' Harper's'', ''Rolling Stone'', ''The New Yo ...

has called ''Argiope appensa'' "almost certainly one of the larger species" which were encountered in vast numbers during his research trip to Guam for the book ''The Song of the Dodo''.

Biology

''Argiope appensa'' construct webs mainly in bushes, between branches, and in human constructions. The webs are rather large and show a white zig-zag silk decoration developed from one corner to the center of the web. These decorations, usually called

stabilimenta A stabilimentum (plural: stabilimenta), also known as a web decoration, is a conspicuous silk structure included in the webs of some species of orb-web spider. Its function is a subject of debate. Origin It is likely that the use of stabiliment ...

, could be a warning device to prevent birds from inadvertently destroying the web.Kerr, A. M
Low Frequency of Stabilimenta in Orb Webs of Argiope appensa (Araneae: Araneidae) from Guam: An Indirect Effect of an Introduced Avian Predator?
Pacific Science (1993), vol. 47, no. 4: 328-337

Gallery

File:AappensaBigIsland.JPG, Community of multi-generational ''Argiope appensa'' on the Big Island of Hawaii File:AappensaHilo.JPG, Mature female being handled in Hilo, Hawaii File:Male and female A. appensa.jpg, Mature female (ventral view) and male (dorsal) File:A Appensa side.jpg, Side view of female File:Argiope appensa spider Nawiliwili.jpg, Female in Kauai Jungle, Hawaii File: Araneidae - Argiope appensa.webm, Female of ''Argiope appensa'' in Hawaii, ventral view. Video clip

References

*Walckenaer, C. A. (1842): Histoire naturelle des Insects. ''Aptères''. Paris, 2: 1-549. {{Taxonbar, from=Q1304668 appensa Spiders of Hawaii Spiders described in 1841 Articles containing video clips