“What’s the largest underground-dwelling invertebrate in the Bay Area? How does it live?” Paul, Berkeley


Well Paul that has to be the tarantula. There are 15 or so species of “tarantulas” in California are in the genus Aphonopelma in a family called the Mygalomorphs. But our spiders are not true tarantulas. The original Lycosa tarantula is found only in Europe and is a member of the wolf spider group.

Every fall the male tarantulas leave the protection of their burrows and search for females. Males are easily identified by the presence of giant pedipalps – large leg-like appendages near the mouth. The male constructs a sperm web where he deposits some seminal fluid. He then takes up a little of that sperm into special reservoirs on the tips of his pedipalps. Now he is ready to roll. Normally these spiders are nocturnal but during the breeding season the males are out night and day cruising for females.

When he finds a female burrow he taps the entrance with his legs and entices her to emerge. This is a dangerous operation. Tarantulas have been known to kill and eat animals much larger than themselves including small rodents, lizards, and even other tarantulas. The female may charge him with her fangs exposed. He grabs her fangs with special spurs on the inside of his front legs. He then flips her on her back and rhythmically uses his pedipalps to brush past her sternum. (Are you beginning to breathe hard here?). He places his packet of sperm in her genital pore and makes a hasty retreat; he doesn’t want to get eaten. In humans mating occasionally follows dinner, in some spiders dinner occasionally follows mating.

The male tarantula will soon die; his job is done. Females on the other hand have been known to live over 20 years! Soon she will plug her burrow and spend the winter safe and secure far underground. Deep in her lair the following spring she will spin a thick egg sac and deposit 500 to 1000 eggs in it. The spiderlings hatch in about a month; the mother tears a small hole in the sac for her babies to emerge. They hang out with her for a while before leaving the burrow. And the cycle for another amazing animal begins anew.

Tarantulas take their name from the small Italian town of Taranto, where they were once numerous. Here tpeople believed that the bite of the tarantula was fatal. Just preceding death the victim entered a state of melancholy called tarantism. In order to survive death you had to listen to music during this tarantism. Not just any music, but the right music, which varied according to the particular whims of the victim.

The doctor would lead the patient into a room where an orchestra was assembled. The doctor would then take the musicians through a few numbers. The patient would be unmoved until the right tune was struck. With a wild look in the eye, he’d get up and begin an uncontrolled frenzy, leaping about, flailing his arms and shrieking (I used to see similar behavior at a Grateful Dead concert). Finally dripping with sweat he’d drop, totally exhausted, but completely cured. The patient would have recovered anyway. Tarantula bites are not fatal, in fact it’s pretty hard to get one to bite you. But it was probably a good opportunity to act out some fantasies.

The best location to view this autumn phenomenon is the inner coast range mountains like Diablo and Hamilton. There is even a tarantula festival in Henry Coe State Park Coe Park on October 6. http://coepark.net/pineridgeassociation/component/eventlist/details/7-tarantula-barbeque
I am not sure which band is playing there however.

Wild Animal Behavior

Q – How have humans influenced wild animal behavior?

A – Most of the world’s 5,000 or so species of mammals are already nocturnal, so the effect of urbanization on their circadian activity is probably nil. Actually, even the nocturnal animals are mostly crepuscular in activity; that is, they have a burst of feeding, moving, and mating at the twilight times—dawn and dusk.

I have noticed in park settings that our local black-tailed deer are active in the early morning, take it easy at midday, and then begin feeding again in the afternoon. Of course, they are active at night as well. In “shruburbia,” where homeowners, children, and dogs are out and about during the day, the deer tend to visit only under cover of darkness to munch those well-watered and delicious roses. So they have altered their diurnal (daytime) activity slightly.

A more obvious change in behavior is with coyotes. These wonderfully adaptive wild canines have different social strategies depending upon the habitats in which they live. In wide-open undisturbed settings, they form monogamous pairs and maintain an active social life with related clans. The offspring often stay with their parents for one or two years and help feed their newborn brothers and sisters. A mated pair may be together for years. They frequently hunt in the day and vocalize both night and day. Early settlers in the West reported seeing very large coyote aggregations (75 or more) in areas of abundant game.

However, in urban zones, or in areas that they are just colonizing, coyotes adopt entirely different lifestyles. They do not interact much with each other, and they don’t form long-lasting monogamous pairs. Often the mother coyote is left to feed the young kits all by herself, while the male keeps more or less to himself. Male territories are larger than the females’, and males may move through several territories before mating. In such uncertain and novel settings, and where humans are present, coyotes vocalize very little, if at all, and don’t move around much in the daytime. In other words, they keep a very low profile. In fact, human residents can be blissfully unaware of the presence of coyotes in the neighborhood until their beloved pet cat is snatched right off the back porch.

Michael Ellis – Ask the Naturalist – Bay Nature Magazine


Q: How does photosynthesis occur in plants that are not obviously green, such as ornamental plum trees with deep purple-colored leaves?  What other chemicals are involved in photosynthesis besides chlorophyll? –Paul, Santa Cruz

A: Photosynthesis is that very elegant chemical process begun 4 billion years ago that jump started all life as we know it on our planet. The word literally means photo = light + synthesis = to put together. Basically six molecules of water plus six molecules of carbon dioxide in the presence of light energy produces one molecule of glucose sugar and emits six molecules of oxygen as a by-product. That sugar drives the living world. Animals eat plants, then breath in oxygen which is used to metabolize the sugar, releasing the solar energy stored in glucose and giving off carbon dioxide as a by product. That is it.

GREEN PLANTS DO THIS: 6 CO2(g) + 6 H2O(l) + light → C6H12O6(aq) + 6 O2(g)

ANIMALS DO THIS: C6H12O6 (aq) + 6O2 (g) → 6CO2 (g) + 6H2O (l) + energy

All photosynthesizing plants have a molecule called Chlorophyll a. This molecule absorbs most of the energy from the violet-blue and reddish-orange part of the spectrum. It does not absorb green; which is reflected back to our eyes. There are also accessory pigments which absorb energy that Chlorophyll a does not. These are chlorophyll b and carotenoids. There are at least 600 known carotenoids; they are split into two classes, xanthophylls and carotenes. They absorb blue light. Xanthophylls are yellow and carotenes are red and orange. Anthocyanin while not directly involved in photosynthesis is an importan pigment that gives stems, leaves, flowers or even fruits their red color.

Many ornamental plants are selected because of their red leaves – Japanese plums, Norway maples, purple smoke bush to name just a few. Obviously they manage to survive quite well without green leaves. At low light levels leaves with chlorophyll a and b are most efficent at photosynthesis. On a sunny day however there is essentially no difference between red and green leaves in trapping the suns energy. I have especially noticed the presence of red in brand new leaves and in many tropical plants. Anthocyanins apparently prevent damage to leaves from ultra intense light energy by absorbing UV light. There is also evidcence that unpalatable compounds are often produced along with Anthocyanins which may indicate to potential herbivores the presence of toxins.

There is still much research to be done in this arena and botanists have been wondering about red vs green leaves for the past 200 years! So you are in good company, Paul

Michael Ellis – Ask the Naturalist – Bay Nature Magazine


Q: I’ve heard stories that ringtails were known to “shack up” with miners during the Gold Rush, yet in 20 years as a wildlife biologist in California with many night surveys in likely habitat, I have encountered two mountain lions, but no ringtails. Where are the ringtails? [Wendy, Martinez]

A: I, too, have wondered about the lack of ringtail sightings in my nocturnal forays. From historical accounts, you’d think every prospector’s cabin had its own family of ringtails, keeping lonely miners company and the area free of rodents. At only three pounds, these diminutive critters are smaller than a house cat, but they’re right up there with sea otters on the cuteness scale—9.9, I’d say. While commonly referred to as “cats,” they are actually related to raccoons and coatis and more distantly to pandas! And they behave much more like weasels than raccoons. Their short legs give them a feline look, but their heads resemble those of small foxes. Their scientific name, Bassariscus astutes, means “clever little fox.” And their namesake bushy tail, banded in black and white, is as long as their 12-inch body. Adapted for nocturnal foraging, ringtails have huge eyes, large ears, and a keen sense of smell. They also have sensitive whiskers called vibrissae that grow not only by their mouths but also above their eyes and on their wrists.

They’re elusive, but also very successful and widespread: ringtails are found from Oregon to Mexico and east to Oklahoma in many different habitats from sea level to 9,000 feet. Ringtails thrive anywhere they can find food. What’s food for a ringtail? Just about anything—fruit, small birds and mammals, leaves, nuts, eggs, and insects—the latter making up about 40 percent of their diet. They are superb hunters and accomplished climbers. They can rotate their back legs 270 degrees, which helps them scale steep cliffs and leap from tree to tree. Their primary predators are probably great horned owls, which hunt using both dim light and sound. So it’s not surprising that ringtails are incredibly quiet and stealthy. That helps them elude those hungry owls while also nabbing their own unfortunate prey.

David Wyatt, a biology professor at Sacramento City College, has been studying ringtails for years. He has live-trapped and radio-collared a number of them in the Sutter Buttes and in riparian areas in the northern Sacramento Valley. He says that sometimes when he’s picking up radio signals and knows a ringtail is right in front of him, he often still can’t see it. But his research and the research of others indicate that ringtails continue to be numerous, though we rarely see them.

So don’t feel too bad Wendy. At least you saw mountain lions!

Michael Ellis – Ask the Naturalist – Bay Nature Magazine

Waterfall Under Golden Gate Bridge

Q: Rumor has it there might have been a waterfall at the Golden Gate during the last ice age, when sea level was at its lowest. Is there any evidence for this? [Cisco, Oakland]

A: Well, there is no incontrovertible evidence for a “waterfall” at the Golden Gate, but there very well could have been one in the past. The earth has undergone a number of ice ages over the last 2.5 million years, when the cooler, wetter climate caused the for-mation of large sheets of ice in the polar regions and at higher elevation, followed by the melting of this ice. This oscillation has caused sea level to periodically rise and fall by as much as 200 to 400 feet over periods of several thousand years.

Some 20,000 years ago, the San Francisco Bay was not a bay, but a broad valley with a river, which we now call the Sacramento, draining the Central Valley through the Car-quinez Strait and heading out to the Pacific through the “Golden Gate.” Except it didn’t meet the ocean at the Golden Gate, as it does now. Instead, it ran for another 27 miles across a broad plain past a series of hills (now the Farallon Islands) before draining into the Pacific. In fact, the now-flooded San Francisco Bay is the exception; for most of its life, the “Bay” has been a river valley.

The deepest part of the Bay, at 350 feet or more, is just west of the Golden Gate Bridge. To the east, bedrock at Racoon Strait (sic) between Angel Island and Tiburon is only 140 feet deep. So in just over two miles, the ancient river dropped more than 200 vertical feet. This most likely would have created a series of cascades, if not a waterfall. And right under the bridge is an extraordinarily deep hole in the ancient river channel (download a colorful 3-d map of the Bay floor at bit.ly/BayFloorMap). The existence of the hole is a bit of a conundrum to geologists, some of whom suspect that a good-size waterfall may have created this large cavity in the bedrock. The sheer volume of water passing through this narrow cut in the Coast Range must have been immense. Today, runoff from nearly 40 percent of California’s land area drains out through the San Fran-cisco Bay. During ice ages, there would have been even more water in the river to carve out the canyon. Waterfall or no, these rushing waters would have been an impressive sight, and sound.

As sea level rose at the end of the last ice age about 8,000 years ago, seawater in-vaded this river valley, creating the modern San Francisco Bay. Evidence of the old riv-erbed can be seen during winter storms when large waves break over the Potato Patch, a four-fathom shoal made up of sand carried by the ancient Sacramento River on its way out to the Pacific some 30 miles to the west. 

Email your questions to atn@baynature.org.