Name: Masha Species: Jewel, Crab or Spiny Spider Gasteracantha cancriformis or Gasteracantha elipsoides Kingdom: Animalia Phylum: Arthropoda Class: Arachnida Order: Araneae Family: Araneidae Genus: Gasteracantha Species: Gasteracantha cancriformis Range: North Carolina to Florida and west to California Color: Black with yellow dots on the bottom. White with black dots on the top. The spines are red. The length for the female is about 15mm Eating habits: Small flying insects but otherwise, unknown by me Reference: |
Masha, a new resident, appeared in our neighbors front garden with a web
that was about 45 degrees (i.e. not vertical). It was quite loose in that
a slight breeze would move the web 5 - 10 cm. There are lengths of
thick silk dispersed along the supporting threads, though I've not been
able to capture this with a photo.
This spiny or jewel spider (some call her a crab spider) ( Gasteracantha cancriformis or Gasteracantha elipsoides ) has very interesting coloration. White with black dots on the top and then black with yellow dots on the bottom. The spines or horns are short, a few mm, and reddish-orange in color. In low light its difficult to see the colors, but captured on a photograph, they are truely beautiful. This afternoon I was able to catch a web building exercise. As I was walking home, I noticed that there was only a skeleton framework of the web. Then I located Masha, she was weaving the radial segments. She extruded silk to build 2 segments in on direction and then 2 segments is approximately 120 degrees and then another 2 segments rotated another 120 degrees. Why 2 segments? She places one segment from the center to the perimeter, attaches it, then moves about 3-4 cm away and using the previous radial spoke to move back to the central core where she attaches the 2nd spoke. She then selects another direction, makes an outward directed spoke, moves 3-4 cm along the perimeters and then makes an inward directed spoke. After finishing all the spokes, she weaves the circumferential fibers as one continuous spiral link. Unlike the banana spider (Nephila clavipes), the spiny (Gasteracantha cancriformis) makes one weave of the circumferential elements, not a course weave and then filling in the gaps. I have some video that I shall try to extract segments to demonstrate the weaving. It is very fast, and with even a slight breeze, the web is moving such that focus is difficult. |
The spiny or jewel spider ( Gasteracantha cancriformis ) builds her web within a super structure of fibers that form a rough pentagon as seen below. The super structure threads have periodic segments of thick silk, I suppose to warn birds etc - that there is an obstacle within. Her web consists of spokes from the periphery convergion on a central hub and a circumferential element, woven like a spiral.
Video Segments (15 sec and 1 min) of weaving circumferential segments Apologies! The motion is due to web movement associated with a slight breeze. Also - the mp4 video may not render with all players - use mov with quicktime if there is a problem. The mpg files should render fine on any player.
C. Frank Starmer