The Australian garden orb weaver spider (''Hortophora transmarina'') is a very common species of
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 ...
with many variants in size, shape, and colour across the coastal and northern regions of
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
. They have very large
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
s when well-fed and exhibit a tremendous colour-range from off-white through tan, brown to almost black. They have a roughly leaf-shaped pattern on the top of their abdomen with a complex outline that is darker than the surrounding area. There may also be several whitish spots or one or more stripes. The spiders'
cephalothorax
The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...
es (heads) and
proximal
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
(closer to the body) leg segments are usually darker, mostly reddish or reddish brown. They are able to change their colour with each
moult
In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
to better match the background upon which they rest during the day.
The spiders are notable for the often large and intricate webs which they weave at night. They are usually
nocturnal
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed sens ...
feeders, resting head down in their webs waiting to catch flying
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s. They make their sticky rounded orb webs near lights and between trees where insects are likely to fly. During the day the spider will often rest somewhere near the web, usually under a leaf or twig, or in a crevice in bark or rock. They are commonly found around human habitation so may be found resting under leaves and in similar places. When disturbed they will retreat towards this rest area, although under imminent danger the spider will drop to the ground and "play dead". Occasionally individual spiders will remain on the web during the day, possibly when prey has not been caught for a while, but this makes them more vulnerable to predation by birds.
Their bite is not dangerous to humans but may induce mild, local pain, redness, and occasionally swelling for a period of 30 minutes up to three to four hours.
The female is larger than the male, having a body length of 20 – 25 mm compared with 15 – 17 mm for the males. Females may also be distinguished by a needle-like
epigynum protruding in the direction of the
spinnerets
A spinneret is a silk-spinning organ of a spider or the larva of an insect. Some adult insects also have spinnerets, such as those borne on the forelegs of Embioptera. Spinnerets are usually on the underside of a spider's opisthosoma, and are ...
.
Images
File:Garden Orb-weaver spider. Cooktown, Australia.jpg, Garden Orb-weaver spider. Cooktown, Australia
Image:Garden orb weaver05.jpg, With captured prey
Image:Eriophora transmarina front.jpg, Facial detail
Image:Eriophora transmarina.jpg, Dorsal and web detail
Image:Orb weaver black bckgrnd03 crop.jpg, Ventral side
File:Male Eriophora Transmarina.JPG, Male
links
Spiders of AustraliaWorld Spider Catalog - Hortophora transmarinaAustralian Spider Photos
Araneidae
Spiders of Australia
{{Araneidae-stub