Natural Reserve System
April newsletter
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On this Earth Day, say "Thanks!" to a spider
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| Silver Argiope spider at the Scripps Coastal Reserve
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Are you afraid of spiders? You shouldn’t be. Serious harm from a spider bite can happen, but it is exceedingly rare. If you were an insect you might want to worry, however. Spiders are predators and consume up to 800 million metric tons of prey, largely insects and their relatives, every year. This includes many pests, so if you see a spider today on Earth Day, say thanks!
Spiders, like most tiny animals, are poorly known. Experts estimate that at most half of all spider species have ever been named or described by scientists. And we have incomplete knowledge about the distribution and life styles of the spiders that have been named. But we are starting to learn about the spiders at Kendall-Frost Marsh! Dr. Sarah Stockwell’s Molecular Methods in Evolution and Ecology students, with a little help from the Wander the Wetlands docents, have begun to establish a baseline of spider diversity at the reserve - we started to document what spiders are there. These will be invaluable data by which to evaluate future environmental change.
How did we do this? First, the Wander the Wetlands docents gamely collected spiders on a Saturday in late January. Then the Molecular Methods students used a technique called DNA barcoding to identify those individual spiders. Students sequence (determine the order of the DNA building blocks) a small bit of DNA from each spider and then compare that sequence to a reference library of sequences. Spiders that match a known DNA sequence in the library are then identified. Below are just a few of the students’ results. Enjoy!
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Spiders at the Kendall-Frost Marsh
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Metaphidippus iviei (Salticidae)This cute little fellow is a member of the family Salticidae, the jumping spiders. The common name is apt. Although he looks almost cuddly these spiders are active, daytime hunters that can jump to catch their prey. They have big eyes, unusually good eyesight, and can jump several times the length of their body. Jumping spiders use a dragline - they tether a line of silk to the surface before they jump - and then use that to catch themselves if they fall or to climb back to their original spot. Other than as a tether, jumping spiders do not use silk or webs to catch prey. They will build silken shelters, however, where they sleep, overwinter, and protect their egg sacs.
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Metaltella simoni (Desidae)
This species of spider is not from here, it is native to South America. We don’t know how it arrived, but it was first collected in the US in Louisiana in 1944 and it spread across the Gulf states and beyond; it was first collected in San Diego near Clairemont High School in 1997. Since then it has become widely established in urban southern California. A prominent local arachnologist was able to “ collected 13 in his San Diego backyard in 12 minutes”. We also don’t know if it is simply a non-native species or if it has crossed the line into being invasive - a species that causes harm, typically by reducing biodiversity. There is some suspicion that M. simoni outcompetes a native spider in Florida, but we have no such information here in California.
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Geolycosa sp. (Lycosidae)
This DNA sequence for this individual had no match in the DNA barcode reference library! This does not mean that it is “new to science” but it does mean that no one has yet sequenced & uploaded its DNA to this database. The closest match was to the genus Geolycosa, however, so we will guess that it is in the wolf spider family (Lycosidae). As the name suggests, wolf spiders are active hunters that do not build webs. Unlike most spiders wolf spiders have excellent eyesight. You can see the extra big eyes in the photo. Wolf spider mothers are the only spiders known to carry their baby spiderlings on their back for several weeks until they can live on their own. Sweet!
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Steatoda grossa (Theridiidae)
This species is in the family Theridiidae, the comb-footed or cobweb spiders. The name comb-foot comes from the row of comb-like bristles on their hind legs; the name cobweb spider comes from the messy, irregular tangle of silken threads that is their web, so unlike the symmetrical orb webs (like the silver Argiope photo above) or shapely funnel webs of other spider families. This family contains the spiders that are most likely to be in your home, in fact this genus is referred to as cupboad spiders. Black widow spiders are also in the family Theridiidae, but Steatoda grossa is thought to prey on black widow spiders ( Insects of Los Angeles Basin). So again, today is a good day to thank a spider!
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Bunny ears cactus (Opunta microdasys) at the Scripps Coastal Reserve
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Wander the Wetlands Saturday April 23, 9 - 11 AMWander the Wetlands is an open-house-style event at the Kendall-Frost Marsh every 2nd and 4th Saturday. You can chat with a docent, look at birds through a spotting scope, or just relax on the porch and enjoy the view of the wetlands & Mission Bay. No pre-registration is necessary.
Weed Warriors Friday April 29, 8 - 10 AMEvery Friday we tackle the invasive weeds at the Scripps Coastal Reserve. Devil's thorn ( Emex spinosa) and crystalline ice plant ( Mesembryanthemum crystallinum) are our current focus. No experience necessary! Please email nrs@ucsd.edu if you would like to join the fun.
Scripps Second Saturday Saturday May 14, 9 - 11 AMAt the Scripps Coastal Reserve there are docent-led tours the 2nd Saturday of each month. Learn about cowboy cologne, our photosynthetic friends & foes, and underground bee nurseries as you walk the half-mile trail with a guide. No pre-registration is necessary.
Wander the Wetlands Saturday May 14, 9 - 11 AMWander the Wetlands is an open-house-style event at the Kendall-Frost Marsh every 2nd and 4th Saturday. You can chat with a docent, look at birds through a spotting scope, or just relax on the porch and enjoy the view of the wetlands & Mission Bay. No pre-registration is necessary.
Kendall-Frost Work Party Saturday May 21, 9 - 11 AMCome to Kendall-Frost Marsh on the 3rd Saturday of every month to help out with restoration activities. Help plant native plants, weed invasive species, mend rabbit-deterring fencing, and lots of other tasks to give some TLC to the marsh and surrounding uplands. Please email nrs@ucsd.edu if you would like to participate.
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