Mushrooms at Crow Point

fairy rings and soldier parades

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A walk on the Boy Scout beach/Crow Point trail is almost always rewarding. There’s a variety of habitats, each of which changes with the seasons in its own way.

In late September, there were no geese to be seen in the big tidal meadow or in the river’s estuary. A northern harrier in brown plumage (female or juvenile) coursed low over the river and meadows, spooking at least one crow. A bit above the highest part of the beach, the last flowers of wild strawberry shone on a background of dark green. Several flocks of pine siskins flitted over the seed heads of meadow plants or zoomed between stands of conifers.

On the way from the parking lot to the beach, in the first riverside meadow, the trail had previously been re-routed to accommodate bank erosion. But this time, another large chunk of the bank had fallen into the river, leading to another trail diversion.

Rather than walk the long beach, I chose to weave my way in and out of the spruce groves that line the berm along the shore. These groves sometimes produce interesting finds, such as a bear skeleton or a flourishing stand of orchids.

This time, it was a mushroom show. I know next to nothing about mushrooms, unfortunately. But I was attracted to three in particular. A medium-sized brown one typically grew in long, curved chains. Troops of very small white ones clustered between spruce roots. (I called these ‘armies’, and a friend saw them as pilgrims on a mission, but ‘troops’ is an accepted informal term, I’ve read). My favorites were tiny yellow ones with orange centers on the cap. These usually grew in troops on the berm, especially in some of the groves.

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Trichloma fairy ring. Photo by Pam Bergeson

To give me some guidance, I enlisted the help of a friend who does know a lot about mushrooms, and we went out there again a few days later. We made only slow progress as we walked along, because there were so many different mushrooms to look at and discuss. There were lots of Amanita muscaria (common name: fly agaric), both red and yellow varieties. They had the customary whitish ‘warts’ on the cap—except when they’d been washed off by heavy rain. (I call the white bits scattered on the cap ‘streusel’, like the crumbly mixture often scattered on muffins or coffee cake). We found huge boletes, now aged and no longer desirable for eating by humans but other critters had been feasting. There were more kinds of brown-capped mushrooms than my old brain could begin to assimilate.

I learned that the curved chains of brown-capped mushrooms belonged to the genus Tricholoma (I decided, early on, that getting the name of the genus was enough for now; species names could wait). Tricholoma fungi form mycorrhizal associations with tree roots, providing soil nutrients to the trees and obtaining carbohydrates made by the trees’ green leaves. The long sweeping arcs sometimes exceeded fifteen feet in length. Shorter arcs made nearly complete rings. So-called ‘fairy rings’ of mushrooms are well-known in both mythology and mycology (the study of fungi), but I have not found a coherent explanation of why they form these arcs in some cases but not in others.

The numerous troops of small whitish mushrooms turned out to be of several species, mostly in the genus Mycena, but a few in the genus Collybia. They are not mycorrhizal but rather decompose fallen plant parts such as old leaves and flowers.

Those tiny, bright yellow mushrooms belong to the genus Mycena, sometimes called fairy bonnets. I would love to know why troops of these were very common in some groves but not in others.

As usual, I am left with many questions. For instance, how does a fungus decide when to produce sporing bodies? The main part of a mushroom-producing fungus is an underground network (mycelium) of thread-like hyphae; the network may be very extensive. When the time is right, the fungus puts up sporing bodies that we call mushrooms. The mushroom cap releases ripe spores that disperse, potentially starting new individual fungi. (Although they are not the same as the seeds of plants, they have the same function). But what makes one time ‘right’ and others not? This year was said to be one of great bolete production—but what were the conditions that made it so?

And why are some mushrooms purple—what is the function of that pigment? Ditto for red, or yellow, or browns. Some mushrooms have massive thick stalks, almost as wide as the cap, while other perch their caps on feeble, spindly stalks. How come? There is so much to be learned!

Thanks to Jenifer Shapland for a primer on local mushrooms.

Crab spiders

voracious little predators

Crab spiders typically are sit-and-wait hunters that ambush insects passing close by, grabbing a victim with two sets of long claws. Small prey can be captured with just the claws, but larger prey is subdued by injection of potent venom that quickly immobilizes the prey. Most of these injection bites are placed between head and thorax or between thorax and abdomen of the victim. Placing its mouthparts in a wound made by the claws, the spider sucks out a little body fluid, mixes it with its own stomach fluid, and reinjects the mix. The mixed fluids go back and forth, with more and more stomach fluids going into the prey. Those fluids turn the soft internal tissues of the prey into liquid, which is then sucked up by the spider. In many cases, feeding begins with the head of the prey, and if the spider is already well fed, only the head contents are consumed; the spider then discards the carcass. Such selective food consumption leaves the question “Why?”. Perhaps the eyes and brain of the prey insect offer special, critical nutrients, or maybe just the most calories. (We see something similar when bears eat just the brain or the eggs from a captured salmon.)

Although some crab spiders hunt in the leaf litter or on tree trunks, the kind we have here (Misumena vatia) habitually hunts on flowers, waiting to nab the visiting insects. Dandelions sometimes make a nice hunting platform, even though they close at night or in the rain. Sometimes the spiders lurk in clusters of flowers, such as the inflorescences of lupines. Misumena vatia can change color from yellow to white and back again, depending on the background color of the flower it sits on, although it may take more than two days to effect the change. So if you see a yellow crab spider on a white thimbleberry flower, you know it hasn’t been there very long.

Finding a patch of flowers to use as a hunting base is probably mostly a matter of luck. A newly hatched spiderling can ‘balloon’ on a breeze that catches its silk thread. If it lands in a good flower patch, that’s a good start. But older, bigger spiders don’t move very far—adult females move only a few meters at most, to find good hunting sites. A variety of flowers within a short distance of each other is required, because the tiny spiderlings have to catch tiny prey, which would probably be most common on small flowers (such as goldenrod), but full-grown spiders need bigger prey and can use bigger flowers. So, to establish themselves successfully, our crab spiders need a patch that provides both small and large flowers, with a flowering season long enough to provide that variety.

In Juneau, where do they find the patches with a long-blooming array of flowers? On some roadsides (until they are mowed) and meadows such as those along Cowee Creek, and maybe in some backyard gardens.

Because adult females are heavy, especially if full of eggs, they can’t move around much, so they have to deal with whatever insects come to the flower they are resting on or another flower very nearby. A detailed study in Maine showed that bumblebees are an important prey, although they are much bigger than the spiders and difficult to capture. In fact, capture success seldom exceeded three percent of attempted attacks. So a lot of bees would have to come by, for the spider to do well. Sizable moths are also good prey, typically available at night, but many flowers close at night and draw no moths. A good foraging patch is one that attracts lots of bees or moths, offering many chances to capture a good prey.

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Crab spider capturing a bumblebee. Photo by Bob Armstrong

A hungry spider also attacks smaller prey, such as hover flies or dance flies, but adult females lose weight on a diet of small insects. Furthermore, the females need to be very well fed in order to produce their eggs; they can lay bigger egg clusters if they are very well fed. In the Maine study, few females captured enough food to produce the maximum possible number of eggs. Juveniles, being small, do well on small prey.

What about the males? They have to feed too, and go about it like the females do. But they are much smaller than females (females are more than ten times bigger) and do not depend so heavily on catching big prey. They don’t have the high costs of egg production and they spend their energies chiefly on running about, looking for females to mate with. When a male finds a recently molted, virgin female, he hops onto her abdomen and inserts sperm into her two genital openings using his pedipalps (appendages next to the ‘jaws’ on the head). Males regularly mate more than once, although it takes the better part of a day to recharge their pedipalps. (Females do so much less often). An older female is generally not as receptive and may be aggressive. In any case, the first male to mate with a female is likely to be the father of the brood, so there is less pay-off to the males from such a mating. An aggressive female may sometimes eat an attentive male, but that is not common in this spider: the males are agile enough to escape quite readily and too small to be a rewarding lunch.

Females lay their eggs inside a folded leaf, suspended in a network of silk, and guard the nest by sitting on the outside. Sitting on the outside, rather than guarding inside the nest as many other spiders do, helps keep away parasitoid wasps, a potentially major source of mortality for spider eggs. A female wasp tries to lay a single egg in the spider’s egg mass; one wasp larva can consume all the spider’s eggs, except in the largest egg masses. A defending crab spider often knocks the wasps off her nest. There is usually one brood per season, at least in Maine and probably here as well, but there could be more, farther south. Egg production typically happens in midsummer, and the eggs hatch almost a month later. The tiny juveniles need small prey that come to small flowers, because they need to feed before hibernating in the leaf litter. Juveniles that are well fed and bigger survive the winter better than small ones. The following summer, they grow some more and molt again, and spend the next winter hibernating. The next spring or early summer, they molt to the adult stage, and probably do not live through the next winter. This basic pattern may, however, vary with conditions.

Crab spiders are not common in Juneau, perhaps in part because there aren’t many good patches of habitat. So if you would like to see a crab spider in action, check out the videos on the following website:

https://www.naturebob.com/those-amazing-crab-spiders.

Thanks to Bob Armstrong for photo and videos, to Doug Jones for the loan of a book by D. H. Morse that details much about these crab spiders in Maine.

Yellowjackets and paper wasps

On a recent walk on Gustavus’ nagoonberry trail, the larger forms of wildlife were absent or in hiding. But my naturalist friend and I spotted a wasp clinging to one of the last goldenrod inflorescences, not moving at all, just resting. That observation led to a brief discussion of “wasp” versus “hornet” versus “yellowjacket”—what’s the difference? So later that day, we did a little online research.

The term “hornet” is officially applied to certain European wasps, one of which is found as an alien in eastern North America. However, we tend to be quite casual in how we apply common names for organisms, and sometimes we just call all wasps ‘hornets’, even though that is not quite correct.

“Wasp” is a good general term for a variety of Hymenoptera that are clearly related to bees but different enough to fall into several taxonomic families. Back in the Midwest, I sometimes saw the huge, beautiful wasps known as cicada-killers as they searched among the flowers for prey. That one doesn’t occur here, but we do have other kinds of wasps, including two that make nests where we can see them.

Up under house eaves, in wood sheds, under car ports, we sometimes see the nests of paper wasps (genus Polistes). These nests are made of chewed-up wood fibers, i.e., paper. Each one consists of a more or less horizontal cluster of brood cells, suspended on a cord. Brood cells house the growing larvae, fed first by the queen and later by siblings that are workers from the first batch of larvae. The queen retires from feeding her offspring then, and just lays more eggs. Adult paper wasps feed on nectar, but the larvae are fed chewed-up insects such as caterpillars.

Another kind of wasp includes several species called yellowjackets. These wasps also chew up wood fiber to make their paper nests, but there are usually two or more clusters of brood cells, one suspended below another, and the whole works is enclosed in an oval, papery covering. (There is more paper involved with these nests than with those of the so-named paper wasps, making one wonder about the naming process). Yellowjacket nests may be suspended from branches or rafters or be constructed underground.

Years ago, on some long-forgotten project in the Midwest, I stumbled over a subterranean yellowjacket nest (a kind known locally as bald-faced hornets…). This angered the whole colony and they took it out on me. Somehow they knew that I was the guilty disturber and not my nearby research companion.

Yellowjacket nests commonly have more brood cells than do paper wasp nests, so there are usually more workers. Neither kind of wasp stores honey in the cells, unlike bees. The wasps feed their larvae on chewed-up insects, while the adults eat both insects and nectar. Some species feed only on live prey, while others also visit carcasses, picnic tables, and succulent garbage. Certain species usurp the nests of other yellowjacket species and the host workers raise the usurper’s brood—they are brood parasites, the cuckoos of the wasp world.

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Yellowjacket queen on willow catkin. Photo by Bob Armstrong

The seasonal cycles of yellowjackets and paper wasps are similar. Toward the end of the summer season, a new queen emerges from her brood cell. Males are also produced at this time, and the queen finds a mate. All the males and workers die before winter, but the new queen and her fertilized eggs hibernate in the soil. She emerges in spring, builds a new nest, and installs that first batch of eggs in their brood cells, starting the cycle again.

A good walk often takes me into unexpected thought directions. It starts with a simple observation (in this case, a wasp on a flower), but one thing leads to another, and it’s fun to see what directions the thoughts take.

End of summer

low water, autumn flowers, mountain fish, and alder eaters

It’s really fall, now—the autumnal equinox has passed, and we’ve all noted the rapidly shortening days. The fireweed leaves are mostly reddish and the seed pods have shed their offspring to the winds. A friend observed that the curly valves of the pods looked like the plants had been given perms—all by the same hairdresser.

Late summer, and the long drought reduced my home pond to little more than a mud puddle. Even so, two broods of mallards visit every day, no doubt drawn by the seed spilled from the feeder that hangs over the erstwhile pond. The young ones are well-feathered and nearly as big as their mothers. The hordes of pine siskins that monopolize the feeder are very messy and lots of seeds fall down where the ducks gobble them up. The two duck families don’t mix at all and typically push each other around.

There weren’t many fish in the pond earlier in the season—just a few juvenile salmon and some sticklebacks. They probably weren’t doing very well in the shallow, warm, and turbid water. I watched a mallard grab a young salmon from the shore and walk off with it before gulping it down. Fish-eating by mallards is not as odd as it might seem: when I worked at the hooligan run in Berners Bay, I often saw ducks eating dead or moribund hooligan.

Late summer, and at low elevations the fireweed is finished blooming. Purple asters are now on show in many places. In some of the meadows near Eagle River there have been nice displays of long-blooming grass-of-Parnassus and—a special treat—some lovely stands of felwort with its small, blue, star-shaped flowers, just starting to bloom. Felwort always seems to bloom late in the summer, when most other flowers are done. It’s something I look forward to.

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Felwort. Photo by David Bergeson

All summer long, I’ve had a pot full of the little pansies called johnny jump-ups near my door. One day in July, I came out that door and said “I’ve been robbed!” The two deer that mutilated the fireweed in the front yard, nibbling the upper leaves down to ragged stumps, had come round and mowed down my little johnnies to a height of about three inches. No flowers left. Well, I nursed those plants back to something like their sprightly selves and they again flowered briskly. But the deer came back and this time they left only one-inch stubs. After some considerable time for recuperation, now the johnnies are trying again, but there are many few flowers this time.

One August day I watched a young buck demolishing more fireweed in front of the house. He slowly wandered along the edge of the drying pond where I have some poorly tended terraces. As I watched, he started chomping on the Canterbury bells. That was just too much. I eased my way slowly toward him and when he finally noticed me (he being much too busy eating!), he went the other way, with determined sedateness and his dignity intact, and so disappeared into the woods. But I reckon the deer are not done with my flowers!

Up at Cropley Lake the fish were rising. These are resident Dolly Varden that mature at a small size, much smaller than the sea-run dollies. There are also resident dollies in the creek that flows from the lake, but I’ve been told that the population in the lake is probably quite separate from the one in the creek, with little or no genetic mixing. The lake population is thought to have been there a long time.

In mid-August, on North Douglas, I happened to notice an alder shrub whose leaves had been reduced to skeletons. Some critter had eaten the blades and left just the veins. A closer look found some of the perpetrators—a cluster of fuzzy white caterpillars. These turned out to be woolly alder sawfly larvae. Later, driving out the road, I noticed other alder stands that were nearly leafless.

In consultation with the helpful FSL entomologist, Liz Graham, I learned that there are at least three kinds of sawflies working on alder leaves. The striped alder sawfly is a native species. The woolly alder sawfly and the green alder sawfly are not native here, although the woolly one seems to be naturalized and the green one has been in this area for several years. Heavy sawfly infestations are patchily distributed, nothing like the widespread swaths of browned hemlocks, whose previous-years’ needles are being decimated by the hemlock sawfly this summer.

Sawflies are not true flies; they are related to bees and wasps. They get the first part of their common name from the long, serrated tube through which females deposit their eggs. I’ve read that the three species deposit eggs in somewhat different parts of the leaf: woolly ones on the underside of the leaf and in the midrib, green ones on the upper leaf surface, and striped ones along the leaf petiole. The eggs take one or two weeks to hatch. The green alder sawfly burrows into bark and wood when it is ready to pupate, but the other two species pupate in the soil; the adults emerge the following year. It takes more than one year of defoliation to kill an alder, but defoliation by the insects means that there is less nitrogen from decaying leaves put into the soil. The nitrogen-fixing bacteria that live in alder roots put lots of nitrogen into the plant, and this gets recycled back to the soil when the leaves decay. I wonder about possible ecological consequences of breaking that nitrogen-recycling pattern.

Hawk moths

master fliers and specialized pollinators

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Bedstraw hawk moth (Hyles gallii) Photo by Bob Armstrong

If you walk through a field of fireweed, you might see spittle bugs and aphids and –if you are lucky—a hawk moth. They hover at flowers on their rather narrow wings, extending their ‘tongues’ to extract nectar. They can fly very fast, which may have given them the common name of ‘hawk.’ They’re also called sphinx moths: when a caterpillar is at rest, it raises the front part of its body and tucks the head down; someone with a vivid imagination saw a resemblance to the famous Egyptian Sphinx.

There are well over fourteen hundred species of hawk moth in the world. Some of them specialize on extracting nectar from orchids and often incidentally (to the moth) pollinating them. Many hawk moths have long proboscides (‘tongues’), suitable for extracting nectar from the long nectar spurs of certain flowers. When there is a good fit between the length of the spur and the length of the proboscis, the moth can pick up pollen on its eyes or face and transfer it to another orchid flower. If the proboscis is too short, the moth can’t reach the nectar in a long spur and is not likely to visit that kind of orchid very often. If the proboscis is too long, the moth’ head or body will not contact the place in the flower where the pollen is produced, so although the moth can steal some nectar, pollination is unlikely (unless it happens that the pollen is contacted by the proboscis itself).

Certainly the most famous of these relationships (as I mentioned in an earlier essay) concerns the Madagascar star orchid, whose prodigiously long (eleven inches or so) nectar spur caused Darwin to predict the existence of a suitable moth with an equally long proboscis. Sure enough, someone else eventually found that predicted moth, in action. Now there are rumors that a second species of long-tongued hawk moth can also reach the nectar and do some pollination of this orchid.

A little closer to home, in the swamps of Florida and Cuba, the ghost orchid lives high up on tree branches. The nectar spur is said to be about five inches long (but variable) and it is now known that several species of hawk moth can pollinate this species. Unfortunately, the orchid is now quite endangered, in part because of over-collecting by too-avid horticulturalists.

Slightly closer to Alaska, in the tall-grass prairies, the fringed prairie orchids are pollinated by hawk moths. The western fringed prairie orchid has a nectar spur over two inches long, which is said to be longer than most other North American orchids. It is known to be pollinated by four species of native hawk moths (perhaps more) and by one non-native species (that was introduced to North America from Eurasia to help control an invasive weed). This species of orchid is designated as ‘threatened’, largely because of habitat loss as the prairies were plowed under for agriculture. But in addition, the moths are at risk from pesticides drifting over from the agricultural fields. Some published accounts say that no seed set is accomplished in the absence of moth pollination, but others say that a little self-pollination without the help of the moths is possible. In either case, reproduction is generally poor.

In Alaska, little seems to be known about the relationships of hawk moths to flower pollination. Of the seven species on record in the state museum, only some are represented by more than a few specimens (thanks to the helpful entomologist, Derek Sikes, for this info!). I’ll summarize a bit about three of them. Here in Juneau, we sometimes see the bedstraw hawk moth (Hyles gallii) as the adults visit fireweed and other flowers. Two local orchid-watchers have seen and photographed this moth visiting the white bog orchid, carrying pollen on its fairly long proboscis (about an inch long). Is this moth a regular pollinator of this orchid? Hawk moths elsewhere are known to pollinate related species of orchid, but it has been thought that this orchid is pollinated mostly by moths that sit on the flower while they sip nectar (instead of hovering, as a hawk moth does). In any case, hawk moths seem to be uncommon around here, so their role in pollination may be occasional at best.

Another hawk moth that we occasionally see here is called the hummingbird hawk moth (Hemaris thysbe). The wings are clear, without any colorful scales. This species is known to visit many kinds of flowers, including some orchids similar to the white bog orchid, but how many of these visits accomplish pollination is not known. The proboscis is of medium length (less than an inch), so deep nectar sources are not available to this moth.

One other fairly well-represented species in the museum collection is the one-eyed sphinx moth (Smerinthus cerisyi), which sports pretty blue eyespots on the hind wings. Although I don’t know if it has been recorded in Juneau, there are records from coastal British Columbia and from near the head of Lynn Canal, so it seems possible that we might see it here. It has an extremely short proboscis (only a few millimeters long), and one source states that it is not functional at all. In that case, the adults would not feed and there would no pollination.

Hawkmoth caterpillars are often called horn worms, for the horn-like projection that sticks up from the rear end. The three Alaska species that I’ve mentioned all have ‘horns’, although not all hawk moth caterpillars do. The caterpillars are herbivorous, commonly eating a variety of leaves. Bedstraw caterpillars eat fireweed, plantain, enchanters nightshade, and many other things, in addition to bedstraw. Hummingbird caterpillars eat snowberry, blueberry, cherry, thistle, clover, and more. One-eyed sphinx caterpillars forage chiefly on willow and poplar, but occasionally other species too.

Visiting new territory

dabbles in California natural history

I recently made a visit to California, stopping briefly in Tahoe and the region around San Jose. There was little opportunity to pursue my usual natural history interests, but here is a small collection of observations.

–A chubby California ground squirrel climbed up a manzanita shrub to eat the fruits that give the shrub its name (manzanita means ‘little apple’).

–A family of Brewer’s blackbirds scoured the ground for picnic scraps, the well-grown juveniles still trying to coax tidbits from the parents. These blackbirds were the common avian scroungers in many picnic areas, waiting for visitors to drop tasty bits. Other moochers around the picnic tables included one or two kinds of chipmunks and the golden-mantled ground squirrel, which looks like a big chippie but lacks the head stripes.

–A group of wild turkeys was a big surprise, seen as we whizzed along a highway. It turns out that turkeys were introduced to this area decades ago from the native Rio Grande population.

–A male western tanager posed next to the road, so everyone in our slow-moving cavalcade got a good look at it. Even the non-birdwatchers enjoyed this colorful fellow.

–Both ponderosa pines and Jeffry pines grow at mid elevations here. They look quite similar, but their the spines on their hefty cones are different: those on ponderosa cones stick out and stab the hand that grabs them, but those of Jeffrey cones are bent back and do not stab. If you can’t find a cone for conducting this test, try smelling the bark. Jeffrey pine bark is aromatic, fruity or vanilla-scented, depending on the observer. My nephew and two of his small offspring joined me in smelling the tree trunks; the rest of the clan took this as confirmation of lunacy.

–On a stroll through a coastal redwood grove, I noted that many of the big trees were circled by dense crowds of small juveniles sprouting at the base of the trunk. Redwoods sometimes form hefty burls at the root crown. This type of burl is known specifically as a lignotuber, composed of numerous dormant buds and food reserves. The buds are reportedly stimulated to sprout if the adult is damaged or begins to die. If the adult actually dies, a few of the sprouts can take over that location, surrounding the old stump. However, unlike the very thick-barked adult, the sprouts would be very vulnerable to ground-fire. Burl sprouts also self-thin rapidly, especially at low light levels; at extremely low light levels, all of them die. Presumably, the crowds of juveniles around these trees had not self-thinned much: some of the small trees were several feet tall, despite the crowding.

–In the same grove, a few of the small redwoods had white, not green, foliage. Lacking chlorophyll, these cannot conduct photosynthesis to produce the carbohydrates needed for growth. So they are dependent on their connections to adjacent trees that do have the usual green foliage. Those connections might be direct (root to root) or via fungal links. The white trees are little parasites!

–The Monterey Bay Aquarium occupied me for several hours, gawking happily at the varied displays. A large, tropical comb jelly was fancifully adorned with more colorful frippery and furbelows than any I’d ever seen before (being accustomed to more modest ones, with their rows of cilia around an oval body). The perilous state of the endemic population of vaquitas in the Gulf of California was featured in one area. These small porpoises get caught in fishing nets and drown; they also have already lost most of their food fishes to greedy humans, who ship just a certain body part to China (for pseudomedical sales). Sadly, there are only thirty or fewer still left.

A video of cuttlefish showed the tentacles shooting out with incredible speed to snag a hapless little shrimp. That fascinating sight captivated me, but I don’t know much about cuttlefish, except that they are related to octopuses, nautiluses, and squid, a group of molluscs collectively known as cephalopods. So I looked up a few bits of information. The two long tentacles are hidden among the eight short arms, when the animal is just cruising around. Most cuttlefish are fairly small, with a body length less than about twenty inches long. They travel by jet propulsion (forcing water out through a siphon) and by undulating the fins on the side of the body; the ones I watched also seemed to walk on some of the arms (but that might have been an illusion). Cuttlefish can change color and pattern rapidly and spew forth a cloud of ink to obscure their movements. They have relatively large brains and excellent vision. They don’t live very long, reportedly just a couple of years. Males fight over females and the winner inserts his sperm into the front of the female’s mantle cavity using his tentacles. Males can even remove the sperm of the female’s previous mate, flushing it away (a tactic not limited to these critters, by the way).

And here are some un-natural history observations: It was a short visit, but it didn’t take long to grow weary of congested highways and traffic delays, the many other roads squirming off in all directions (GPS was essential), beaches that were packed with bodies in various stages of sunburn, parks thronged with humans. Almost every flat expanse that wasn’t covered with buildings featured vast agricultural fields of sunflowers or artichokes or other monocultures. Gigantic strawberry fields harbored odd, round-backed creatures near every row—stoop-labor at work. Some enormous fields were entirely sheathed in plastic, reportedly for weed control. Not my idea of a place to live! I was very glad to leave it and come Home!

Hiding in plain sight

camouflage is more than just visual

When the presence of an animal is difficult to detect or it is hard to locate, it is said to be cryptic. Think of a female mallard sitting on her nest; her mottled brown feathers are good camouflage—they make her look like a little heap of old leaves, not readily distinguishable from the background. We may actually be seeing her but be unable to register her presence; we just don’t detect her, much less locate her nest. She is not out of sight, like bunny in a burrow; she is hidden plain sight.

A famous case of background matching was very well documented. The peppered moth (Biston betularia) in the UK likes to rest on lichen-covered tree trunks and branches. The typical form of this moth has white wings speckled with black spots. The wings also reflect UV light, but even that has a speckled pattern. The speckled pattern makes the resting moth almost invisible as it sits on the tree bark.

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Photo by Bob Armstrong

During the Industrial Revolution in England, beginning in the mid 1800s or so, pollution from factories killed off many of the lichens and the tree bark became blackened with soot. Then the typical form of the moth was very conspicuous against the dark bark and they were readily picked off by hungry birds. A mutant form with black wings, much less noticeable on the sooty trees, then became more common. Natural selection in action!

More recently, industry has become environmentally somewhat cleaner, the trees are not so dark, and the black form is vulnerable to predation. As a result, the white, typical form of the moth is again becoming common.

Because we humans are so heavily oriented to visual things, we usually think of visual cryptic-ness (or crypsis). But why not think of crypsis that relates to other sensory systems? There are several studies suggesting that there may acoustic or olfactory crypsis, and hints for other sensory modalities.

–Acoustic signals are used by many animals for courtship or other communication among individuals of the same species. For instance, males of a neotropical frog make complex calls to attract females, especially when several males are calling simultaneously. But in the presence of predatory bats, they simplify their calls, even though the females prefer the complex ones. At the price of reduced attractiveness, the simpler call appeared to make the male callers less detectable to the bats. They didn’t completely stop calling—which would be acoustically hiding. They just became less detectable.

Many small birds produce a high-frequency, thin alarm call (“seet”), which does not carry very far. This is thought to be more difficult to locate than the usual contact or distress calls. Experiments with captive hawks indicated that these predators had trouble locating the source of the sound and attacked less often, when the potential prey used the high-frequency calls. The small birds can hear the call and be on the watch for trouble, but they don’t need to know the exact location of the caller.

–The leaf-eating caterpillars of another moth (that’s closely related to the peppered moth) look a lot like little twigs, which might protect them from birds but not from predatory ants that hunt primarily by smell. Yet such ants just walked over the caterpillars as if they weren’t there at all and didn’t attack them. However, if the caterpillars were transferred to a different food plant, the ants attacked them readily. Then, after the caterpillars had fed on the new food plant for a while and molted to the next larval stage, they were again ignored by the ants. In this case, the protection comes from matching the chemical constitution of the food plant.

Some elaborate studies of herbivorous pine bark beetles compared the chemical signals and the responses of predatory beetles in different areas (California and Wisconsin). Pine bark beetles use chemical signals called pheromones to attract others of the same species. Predatory beetles cue in on those signals. As might be expected, California pine bark beetles liked their own pheromones better than the Wisconsin ones, and vice versa. But the California predators homed in better on the Wisconsin pheromones, and the Wisconsin predators homed in on the California pheromones better than on the local ones of each population. In other words, the prey were less apparent to local enemies than distant ones, suggesting they were chemically somewhat cryptic.

Birds have a preen glad just above the tail that produces oils and waxes that the birds use to dress their feathers. A fascinating study revealed that the normal waxes are replaced by less volatile waxes during the nesting season of several ground-nesting shorebirds. Furthermore, if only the female of these species does the incubating, then only the females show the shift in wax composition. Ground-nesting birds are particularly vulnerable to predation by mammals, and experiments with a search dog trained to the smell of these waxes showed that the dog was less able to detect the waxes produced in the nesting season.

–In addition, there are hints—but only hints—that shifts in electrical fields, or in production of wakes by swimming animals, or in substrate vibrations have the potential to be used by prey animals to whom crypsis could be advantageous. There are, potentially, many ways to be hidden in plain ‘sight’. And many investigations are needed. In the meantime, it is useful and interesting to contemplate things beyond our usual ken.

A big thank you to the gracious CBJ librarians who promptly obtained a necessary reference for me!