Making the connection

getting sperm cells and egg cells together

Sexual reproduction involves sperm fertilizing eggs, producing zygotes that become embryos. There are many ways ofachieving fertilization. Plants do it the help of pollen-carrying animals and wind (or water) currents, or sometimes just by dumping self-pollen on the receptive surface in the same flower. 

Animals exhibit an astounding array of getting sperm and egg together. The seemingly simplest technique is broad-cast spawning; male and female cast their spawn into the water currents and hope for the best (in some ways, rather similar towind-pollinated plants). More spatially focused, salmon spawn next to each other, casting sperm and eggs into the water near a nest. There is no physical sexual contact. In such cases, fertilization is external, in the environment.

There are many ways of achieving internal fertilization, inside a female. Various insects and salamanders use no-contact sex, often making females do the work: males deposit bags of sperm on the outside of their bodies or on the substrate, and females come by to pick them up. Most centipede females pick up sperm bags deposited by males, but in one lineage the males put sperm into a silken net held by the female, who then takes them in.

Sexual contact of some sort comes in a fantastic array of arrangements, and it can be fun to imagine how they all happened to evolve. Here is a sampling:

We all know how males of humans and other mammals deliver sperm. A male’s intromittent (“to place inside”) organ (a.k.a., a penis) places sperm inside a female’s reproductive tract. Some other animals also deliver sperm this way, although the intromittent structures often have different names. Sharks have a pair of claspers near the genital opening that are inserted in a female to guide sperm delivery. Various invertebrates transfer sperm using their legs or mandibles; octopuses use a special arm to insert sperm to a female mantle cavity. Some nematode worms have cuticular spines that are inserted and guide sperm into the female’s genital opening. Male bedbugs deposit sperm directly through the female body wall (never mind the niceties of genital openings), where there is a special internal organ from which the sperm migrate to the ovaries; and there the eggs are fertilized as they are released.

Most reptiles have intromittent organs, in some cases (turtles) a penis but in lizards and snakes there are two ‘hemipenises’, although only one is used at a time. Most birds mate by pressing the genital opening of a male to that of a female. But a few birds, such as ostriches, emus, and ducks, have intromittent organs (penises). When extended, some these are longer than the body of the male.

Dragonflies and damselflies have an apparently unique arrangement. Males store their sperm in one of the first abdominal segments; using a pair of clasping appendages at the end of the abdomen, they grab a ready female behind her head. The female then circles her own abdomen under the grabbing male to bring her genital opening in contact with the segment where sperm were stored. Males have an intromittent organ there, which transfers his sperm (and in some cases removes the sperm of previous matings!).

Northern Bluet damselflies. Photo by Bob Armstrong

If all of that is not sufficiently astonishing, consider the fishes; there are more kinds of fishes than all the other vertebrates collectively. And they have some surprising ways of delivering sperm; here are a few examples:

–in some African cichlids, a female approaches a male, who releases sperm that she sucks up to fertilize the eggs she holds in her mouth.

–certain armored catfish go one step farther, females sucking up sperm directly from males’ genital openings and passing them very quickly and viably through the digestive tract. She releases them onto a bunch of eggs that she holds on her pelvic fins.

–male guppies, swordtails, and mollies possess an intromittent organ called a gonopodium. It’s a modified anal fin, long enough to be waved around to attract attention and inserted into a female genital opening to deliver sperm.

–the priapium fishes of southeast Asia bear their genital parts(along with the end of the digestive tract) under the chin (both male and female). The male intromittent organ or priapium (named for Priapus, the ancient Greek god of fertility) is derived from the pelvic girdle and fins. It is bony and muscular and faces rear-ward; it bears a serrated hook, presumably for holding on to a female while sperm are inserted. Reportedly, these little fish mate head-to-head but at an angle, because the priapium is asymmetrical, tending to lean either left or right.

–European bitterling females insert their eggs into a mussel body cavity, using the mussel’s exhalant siphon. Males put their sperm through the mussel’s inhalant siphon, and fertilization takes place inside the mussel. Little bitterlings are brooded by the mussel.

–seahorse and pipefish males hold their sperm in an abdominal pouch. Females do the approaching: they deposit their eggs in the pouch, where they are fertilized

Columbia Spotted Frogs

a glimpse of some little-known local amphibians

A friend told me about a place where frogs were breeding, so I went to look. Not a frog in sight, except for a pair of legs disappearing under an algal mat. But I went back a few hours later, when the day had warmed up, and there they were—at least a dozen of them. The males were singing, if one can call it that: the ‘song’ is a series of grunts, and different males sang on slightly different pitches. Occasionally an eager male approached another frog and tried to grab it from behind, which is the usual position for fertilizing eggs as they emerge from a female. Males have sturdy forearms and strong thumbs for the purpose of holding a female in an embrace called amplexus. But as I watched, the male was kicked off by the presumed female; either she wasn’t ready to mate or ‘she’ was really another ‘he’.

Those singing frogs are probably Columbia spotted frogs, which are native to Southeast Alaska, occurring chiefly in the transboundary river valleys. How they got to Juneau is not known—possibly with help from humans. However, in recent years, they have been seen in several places in the Mendenhall Valley and, a few years ago, specimens were sent to an expert for genetic analysis, which determined the species identity.

Columbia-spotted-frog-Kerry-howard
Photo by Kerry Howard

Columbia spotted frogs hibernate in ponds, springs, beaver dams, and under stream cut-banks where it doesn’t freeze and moisture has adequate dissolved oxygen for them to breathe (through the skin). However, they are not dormant in winter; they can move around, sometimes several meters underwater to a new wintering spot. Come spring, males emerge first; they (unusual for amphibians) then choose an egg-laying site in warm, shallow water. Later-emerging females (up to 100mm long) find the males’ chosen sites. They are larger than males (up to about 70mm) and can lay hundreds of eggs in a globular mass.

Each fertilized egg is surrounded by two jelly layers and takes up to three weeks to hatch; the time is shorter when the water is warm. The tadpoles are about eight millimeters long when they hatch. They can grow up to ninety millimeters (total length) by the time they lose their tails, grow legs, and look like little frogs, but some transform at smaller sizes. If conditions are right, they may transform in their first summer, but otherwise they can hibernate until the next year. The froglets grow but don’t become sexually mature for two to six years, depending on conditions. Males mature at an earlier age than females but have shorter lives, on average. Adults can live for several years: in some regions up to about twelve years for females and ten years for males, but elsewhere just seven years for females and three for males.

The frogs feed primarily on a variety of small insects but also eat snails, worms, and (rarely) a tadpole. Tadpoles are typically herbivorous: they scrape vegetation and filter the fragments; they also filter detritus and occasionally scrape a dying tadpole.

Spotted frogs show a fair degree of site fidelity for breeding and hibernation. They can travel quite long distances overland, from a hibernation site to a breeding site. Then they may move to a summer feeding site and eventually back to a hibernation site. Travels up to about six hundred meters long have been recorded.

This species, along with other amphibians in North America, is at risk from a lethal fungus infection that has decimated other amphibian populations. Spotted frogs (and our western toads, wood frogs, and other native amphibians) are legally protected: one is not allowed to “hold, transport, or release” them without a permit from ADFG.

Spring colors

glimpses of red, yellow and purple herald the season

There often comes a time in early spring when the seasonal progress seems to stall—there are still freezing temperatures at night, many ponds are still ice-covered, the iris shoots in the meadows aren’t getting perceptibly bigger, meadow grasses and sedges lie flat and dead, the lady ferns stay humped under their old dark fronds—and we get impatient for more signs of spring.

That is a good time to notice little spots of color in the forests and meadows. Folks who live in Southeast had better like green and gray, because those colors are the common background on the landscape—green conifers and frequent gray clouds. One can add ‘brown’ for all the dead grasses and sedges lying in the meadows. But the little bright spots of other colors are a visual treat, adding interest to a walk.

Touches of red pop up in several ways:

–Ruby red berries of so-called false lily of the valley lie nestled like glowing jewels in the moss. These are last year’s fruits that typically don’t ripen until they have overwintered. They will feed the early-arriving robins and then the hermit thrushes.

–Red twigs of the early-blueberry shrubs gleam, adding a pleasing contrast in the still-leafless understory. That observation brings up a question: why do these twigs turn red but not (or so I am told by those who know more than I do) those of the later-blooming Alaska blueberry?

–A few translucent red berries of high-bush cranberry hang at the ends of thin branches, uneaten by bears or pine grosbeaks or anybody else last fall or winter.

–A flash of red on the side of a tree trunk helps to advertise the presence of a red-breasted sapsucker as it hitches its way upward, tapping the bark.

–Along the roadsides, the male catkins of red alder make a swathe of a duller red that is nevertheless very noticeable against the conifers’ green. As the catkins mature, they droop and gradually open to release pollen, and the redness fades.

In residential areas, gardens of multicolored crocuses attract queen bumblebees, busily searching for nectar deep in the flower and grooming pollen off their heads. Some of them probably collect pollen too. Away from settled areas, however, those queens have only male pussy-willows as a source of nectar or pollen, until the early blueberries bloom (adding pinkish-white to the color-scape).

A favorite of many folks is the bright yellow of skunk cabbage. First appearing as a yellow spear emerging from wet places, the hood (or spathe) around the cylindrical inflorescence expands. It helps attract pollinating insects and also happens to provide shelter for the little beetles that come to the small flowers of the inflorescences to feed—and also to court and mate, and incidentally pollinate the flowers. Skunk cabbage provides a ‘progressive party’ of color, because different stands mature at different times as their specific locations warm up. Even one skunk cabbage is delightful; a whole pond full of them is spectacular.

Many of us look for purple mountain saxifrage in early spring. It likes to grow on cliffs and other rocky places, so it is very localized. We always feel rewarded when we find the first blooming ones each spring.

At somewhat higher elevations, Cooley’s false buttercups make splashes of yellow. And don’t forget to look for the violets!

Of course, impatience doesn’t suffice to hurry spring along. But it will come—flocks of robins now skitter along beaches, mallards congregate in the ice-free part of Riverside Park pond, the early songsters are heard more often. Ruby-crowned kinglets now serenade my house daily!

I never tire of watching the prolonged arrival of spring. The basic patterns are generally consistent, but always with some little variations and even surprises. This year, the big difference is what is missing: there is very little snow on the mountains. The rocky mountainsides are showing all too clearly and the usual cornice on Thunder Mountain hardly developed at all. The lack of snow ‘upstairs’ will surely have serious consequences, reducing our sources of water and hydropower and the water supply for the creeks where salmon usually spawn.

Mink

thoughts on a widespread local mustelid

Right after a little (belated) snowfall in early December, I chanced to be prowling around some ponds in the Mendenhall Glacier Rec Area. Mink feet had been there before me, leaving crisply defined footprints in the trails. That mink mostly kept to the foot paths rather than humping over and under the frozen grasses, but made occasional forays to the edges of the almost-frozen ponds. Mink –and deer, bear, and porcupines—often use ‘our’ trails, where there is easy going; snowshoe hares don’t seem to do so very often.

Mink can climb very well and have a rotatable ankle joint that lets them come down a tree headfirst (like a squirrel). But they usually hunt on the ground and in shallow water, both salt and fresh. They swim well, with partially webbed toes, and can dive several meters deep. Their fur is water-repellent. They live all over Alaska, except for some islands and the very far north, reaching high densities in Southeast (except where heavily trapped).

Mink-sleeping-by-bob-armstrong
Photo by Bob Armstrong

Dens are usually near water—in hollow logs or burrows, under tree roots, often in an abandoned den of some other animal, such as a beaver or marmot. The video cam at the visitor center sometimes catches a mink exploring even the occupied beaver lodge in Steep Creek. Mink aren’t likely to use a burrow that belongs to an otter, however, because relationships between mink and otter are generally hostile. They share many of the same eating habits, and otters sometimes kill and eat mink.

Mink are opportunistic foragers for meat of all sorts—everything from bugs and earthworms to fish, small mammals, and birds. When foraging in the intertidal zone, they take crabs, clams, little fish, and snails. Mink also gobble up bird eggs and carrion, including salmon carcasses. Cannibalism sometimes occurs. A big male mink sometimes may take down a hare or muskrat or a sitting bird twice its own size.

Mink-with-gunnel-by-bob-armstrong
Photo by Bob Armstrong

Mink are fierce enough to tackle prey that is bigger than themselves. Years ago, however, my old cat who was an experienced hunter, observed a mink travelling on the other side of my home pond and got wildly excited. She could hardly sit still at the window, bumping into the glass, whining, champing her teeth, twitching all over. Little did she know that she would become mink lunchmeat, had she been outdoors and free to engage with this so-attractive creature.

Mating, for mink, occurs in early spring and young are generally born in June. There may be as many as ten of them in a litter, but four or five would be more usual. Both male and female mate promiscuously, so litter mates may have different fathers. Mating often begins with a rough and no doubt boisterous fight that may leave the female with some wounds. The male then grabs the female by the back of the neck and they copulate, often several times. Copulation is a prolonged process, sometimes lasting as hour.

Eggs are fertilized over a period of several days but do not begin to develop immediately. Mink, along with other members of the weasel family, delay the implantation of the fertilized egg in the wall of the uterus. That egg may float around for several weeks before attaching to the uterine wall, getting a blood supply (via the placenta) from the mother, and starting to develop. From implantation to birth takes only about a month but, as a result of delayed implantation, there can be as many as three months between copulation and birthing.

Kits are born blind, deaf, thinly furred, and toothless. They get their milk teeth after about sixteen days, and their permanent teeth begin to erupt after about six weeks. Their eyes open at a little over three weeks and weaning occurs at about five weeks. Kits start hunting, along with the mother, at about eight weeks of age, but become independent after another month and disperse to find their own home ranges. They mature by the next spring and can breed then.

American mink were introduced to Europe decades ago and now occur across much of northern Eurasia. They compete with the smaller, native Eurasian mink, whose populations have declined dramatically from that competition and many other factors. Mink were also introduced, more recently, to southern South America, which previously lacked any similar predator—no doubt the expanding mink populations cause consternation and carnage among the native riparian and shoreline birds there.

Disruptive Coloration

hiding in plain sight

Just above a stony beach on the way to Lena Point, a patch of yellow paintbrush caught my eye. Inspecting one of the blossoms, I found a beautiful little green caterpillar lying in the curve of one of the outer bracts. It had a narrow white longitudinal line down its back. If that caterpillar had rested on a green leaf or petiole, perhaps the conspicuous white line would draw a predator’s attention, distracting it from the whole body of the caterpillar. Furthermore, that white line would have disguised its real shape, visually dividing it into parts that could seem to be unrelated to each other. And thus, a caterpillar-hunting bird might pass it by.

Patterns that visually break up the shape of an animal’s body are called ‘disruptive coloration’, a common anti-predator ploy of many animals. If it is to work as designed, the animal must behave in a way that suits its pattern. However, this little green caterpillar on a yellow bract was not behaving in a way that best utilized its color pattern. (Maybe it would get away with this apparent mistake by being somewhat concealed within the curved bract.)

Disruptive coloration is often combined with some form of color-matching, such that just part of an animal matches the background (if that caterpillar had been on a green stem, for instance). The blotchy browns on the back of an incubating female mallard might generally resemble a heap of dead leaves. The camouflage effect would be enhanced if the blotches obscured the outline of the sitting duck and even more so if some of the blotches matched the area around the nest.

The optical tricks of disruptive coloration take many forms—not just any color, nor any pattern, nor any arrangement of tone will do. First of all, the effect of a disruptive pattern is enhanced when the color of some patches match the background (as noted above for the mallard) and other patches differ markedly. This makes some parts of the animal fade away visually, while others stand out. In addition, the disruptive effect is greatly intensified if contrasting light and dark tones are adjacent to each other; the more conspicuous patches dominate a predator’s vision, letting the true shape of the prey animal fade back. These effects are strongest if the transition from light to dark tones is sharply defined and not gradual.

A further complexity is provided by a false appearance of relief: colored patches appear to be at different levels or perhaps sloped. This can be accomplished by gradations in tone and is more effective when a light patch becomes still lighter and an adjacent dark patch become still darker at the place where the two patches meet. This illusion can make a flat surface look three-dimensional, or a rounded surface look flat, distracting an observer from the real shape.

Breaking up the body outline may sometimes be accomplished in unexpected ways. For example, experiments have suggested that contrasting marks along the edges of butterfly wings may make the wings less recognizable to avian predators, and thus reduce the risk of predation. Sometimes, color patterns seem to tie disparate body parts together—uniting discontinuous parts; in short, this is the opposite of breaking up a continuous surface or outline. For example, the dark bands on the legs of some frogs seem to merge with similar bands on the body when the legs are folded, so a frog becomes a banded lump with no apparent froggy legs.

All of these delusionary optical tricks are well-known to artists. However, I’ve read that those who use camouflage for military or hunting purposes were initially very reluctant to believe them and so required a lot of persuasion. Of course, Mother Nature has been doing these tricks via mutation and natural selection for eons.

That’s a lot of words sparked by seeing one little caterpillar! And I haven’t even touched on the more famous ways of hiding in plain sight, such as looking like a stick or a leaf or a bird dropping or a bit of algae or some dangerous critter or….Another time, perhaps.

Snow buntings

far northern nesters

snow-bunting-Jos
Photo by Jos Bakker

As a few green shoots popped up in intertidal meadows and along the beach fringes in the middle of March, a welcome avian harbinger of spring arrived: a small flock of snow buntings foraged among the dead grasses in the Lemon Creek wetlands. They were probably finding fallen seeds as well as some marine arthropods, such as amphipods.

Snow buntings nest in Arctic regions all around the world, as well as in alpine areas somewhat farther south. In western North America, for example, they have been recorded to nest in the high mountains of extreme northwestern British Columbia and parts of the Yukon. In Alaska, there are alpine nesting records from (for example) Katmai, Kenai, the Alaska Range, and even near the Muir Glacier in Glacier Bay.

Most snow buntings migrate south for the winter, spending several months in southern Canada and the northern tier of the contiguous U. S. However, in our part of the world, they sometimes winter at various places in the Interior of Alaska and the Seward Peninsula. And in the Aleutians and Pribilofs, most of the buntings are reported to be resident all year round, foraging in snow-free alpine areas and in the beach rye near the coasts.

The timing of arrival for northward migrants no doubt varies from year to year, depending on weather and snow cover and who knows what other factors. Sometimes these birds arrive quite early in the season: On the Seward Peninsula, the first migrants might be seen in early March; at Anatuvuk, it might be early April.

Male buntings migrate northward earlier than females, sometimes arriving on their nesting grounds perilously early and becoming victims of late snowstorms that cover the ground where food might be found. However, there are advantages to arriving early and staking out the best nest sites and territories. So if all goes well, the males set up their territories in open country and defend their borders against other males. Females generally arrive a few weeks later. Well before then, the males have lost the brownish edges of their feathers and now sport a resplendent white and black plumage.

Snow buntings like to nest in rock crevices; sometimes the nest is a foot or more deep in a crack, well-concealed and protected from wind (but not from cold). Sometimes a niche under a boulder suffices. If cracks in a cliff or a pile of boulders are not available, buntings may resort to heaps of driftwood or human debris (such as junked cars) or even niches in buildings. Suitable nest sites are thought to be quite limited, which would make it advantageous for males to claim them early in the season. At least in some regions, the territories function chiefly to claim nest sites, and the adults may forage much more widely.

When the females arrive, they no doubt look around at several males and possible nest sites. Eventually, they pair up with their chosen males; buntings are typically socially monogamous—one male with one female, although a rare male might get two mates. Females are said to be very aggressive toward other females, which may reflect the limited availability of nest sites and which may tend to enforce the social monogamy. However, if buntings are like most other birds that have been studied closely, they too sometimes make extra-curricular excursions, so some of the chicks in a nest may have different fathers.

A mated pair checks out possible nest sites together. Then females do the nest-building, generally accompanied by their mates as they gather material. That may reinforce the pair bond and reduce the chances of copulations outside of the pair bond. The number of eggs in a nest varies a lot but apparently is often four to six eggs, the average clutch size increasing slightly with latitude. Females do all the incubating, although at least in some part of the species’ geographic range, males feed their mates while they are sitting on their eggs. Incubation commonly begins before all the eggs have been laid, so some chicks hatch later than others in the same nest. Both male and female feed chicks in the nest, but fledglings are divided into two groups, each one tended by one parent. Males typically take charge of the early fledglings while females stay with the chicks still in the nest.

The role of males in determining the number of chicks produced from a nest can be important, depending on circumstances. For instance, one set of studies showed that when a male fed his mate during incubation, hatching success was improved, compared to nests at which males that did not feed their mates. And in years of poor food supply, widowed females raised fewer chicks, and those chicks were thinner, than the chicks in nests tended by both parents. Some studies have shown that even if chick-feeding rates increase at very low temperatures, that is not enough for the chicks to survive. But still other studies have not found some of these results, indicating that the reproductive success of buntings depends on a variety of factors that vary with place and time.

The nesting biology of snow buntings has been studied is some detail in a variety of places such as Svalbard, Spitzbergen, Greenland, and Nunavut (Canada), but apparently not in Alaska. Given that researchers in the various places at differing times have not always observed the same patterns, it seems that some detailed studies of Alaska populations would be very useful in determining what is happening here.

That is particularly so because the numbers of snow buntings may be declining, at least in North America, although more research is needed to confirm this. On-going climate change and decreasing snow cover in the Arctic may change this apparent trend, provided there are no major ecological problems (such as pesticides) in the wintering range.

Plants that aren’t green

finding other sources of metabolites

Most of us think of plants as being green, at least in summer. The green comes from the pigment chlorophyll, which uses sunlight to knit carbon dioxide and water together, forming carbohydrates that the plant can metabolize. Lucky for us, oxygen is a by-product of the process. There are a few local plants, however, that don’t have chlorophyll, or at least very little, so they don’t do photosynthesis and have to obtain their energy elsewhere. Here are examples:

Northern ground cone. This interesting Beringian plant goes by the reverberating scientific name of Boschniakia rossica, named for a Russian botanist Boschniak and presumably someone named Ross. Such names reflect nothing about the plant itself, obviously, and only show who knew whom. That’s a shame, because this plant is rather weird and wonderful.

Northern ground cone got its common name because, to some people, the above-ground plant resembles a pine cone. It is common in certain places around here, mostly where there are alder trees. Lacking chlorophyll, it cannot synthesize carbohydrates for itself. Northern ground cone is entirely parasitic, getting its nutrition from other living plants, especially alders but also other species.

The brownish spike that emerges from the ground in summer is the inflorescence, bearing numerous small flowers. When mature, the spike produces huge numbers of tiny seeds.

The plant is reputed to have some medicinal value for humans (although, like many plant medicines, it has some toxic properties too), but part of my interest in it stems from observing that it seems to be a favored food item for bears. In the Dredge Lake area, for example, I often see wide swaths of ‘rototilling’, showing where bears have been foraging for northern ground cone. Bears seek out the underground base of the spike and generally leave behind the spike itself. The stem-bases are not notably rich in basic nutrients such as nitrogen, phosphorous, potassium, or calcium, and probably provide carbohydrates. When bears have been eating lots of ground cone, their scats look (to me) rather like mushy cracked-wheat porridge.

fly-entering-groundcone-flower-by-bob-armstrong
A fly enters the flower of a northern groundcone. Photo by Bob Armstrong

The tiny flowers are accessible to small insects, which are sometimes seen to visit, but it is apparently not known if they are pollinators. A different species of ground cone is reported to be self-pollinating, and a little fly sometimes attacks the flowers of that species. But the story for northern ground cone is yet to be discovered.

Pinesap. This is another strange plant that lacks chlorophyll. Pinesap (alternatively, Dutchman’s pipe) grows under conifer trees. It seems to be much rarer than ground cone in our area, as I have almost never seen it around here. It is sometimes said to be saprophytic, obtaining nutrients from decaying vegetation, but the reality is more complex. This plant and its close relatives are obligately dependent on mycorrhizal fungi whose underground filaments connect to the roots of nearby trees. The fungi draw nutrients from the host trees and delivery them to the pine sap plants. Thus, the pine saps are indirectly parasitic. Pine saps have yellowish or reddish stems, with yellowish or red-tinged flowers usually bent over to one side. When the fruits mature, however, they are upright on the stem. Bumblebees are reported to be the most important pollinators.

Certain local orchids are also saprophytic. We have two species of coral-root orchids, both of which are said to be saprophytic, but again the arrangement may be more complicated. In addition to needing mycorrhizal fungi for seed germination, these plants may, like the pine sap, actually obtain nutrition via their associated fungi that drain nutrients from nearby host plants. In addition, one coralroot orchid is said to have small amounts of chlorophyll and thus synthesize some of its own carbohydrates. Coralroots may be pollinated by small flies, such as dance flies, but probably also have the capacity for self-pollination.

Prowling the intertidal

variety and mystery in a challenging habitat

I find it great fun to go out on a minus tide and prowl along the exposed intertidal zone. It’s a bit like a treasure hunt—seeing how many different kinds of invertebrates and little fishes I can find. Being a terrestrial ecologist, I often can’t put specific names on what I see, but the variety of colors and body form is always intriguing.

Many of the critters like to hide under rocks, so I have to turn over those rocks—very carefully, so as not to crush the animals. When I’m done inspecting what’s been exposed, I try to put each rock back exactly as it was, again without crushing anybody, to preserve them and their hiding places. On a recent low tide, I was dismayed to see that other searchers had often not replaced the turned rocks, leaving the various animals exposed to hot sun and predators.

Seeing all those intertidal invertebrates made me think about the many ways they have for eating, many of which have no counterparts among the vertebrates. Most vertebrates have jaws, sometimes with teeth; only a few lack jaws altogether (lampreys and hagfish). It’s very different, among the invertebrates.

In the intertidal zone, stand in one spot and contemplate the several styles of feeding used by the array of invertebrates there. Sea cucumbers filter small particles from the water using tentacles; barnacles do so with their legs. Sea stars evert their stomachs, either wrapping a prey item or inserting the stomach into a clam shell to digest the meat. Crabs mince and nibble their prey to bits, using pairs of sharp mouthparts. Snails of many sorts rasp their food with a file-like structure: predatory snails rasp a hole in the shells of mussels or clams or other snails, shredding the meaty contents, while the herbivorous ones graze by scraping algae off rocks and seaweeds. Ribbon worms, pile worms, and iridescent worms have a bulbous proboscis that can be extruded; armed with sharp hooks or daggers, the proboscis clamps onto the prey and pulls it back into the mouth of the predator. Detritus feeders, such as lugworms, vacuum up soft junk from the substrate. And that’s just a sample.

We often find several kinds of sea cucumbers, sea stars, snails, chitons, anemones, and so on, each time we go cruising the low tide line. Occasionally, we find something unusual or uncommon, such as the nudibranch (a shell-less mollusc) that eats barnacles. Recently, we found numerous odd lozenges of a jelly-like substance strewn over the sands; each little oval was about an inch long and contained rows of tiny eggs or embryos.

This was a big mystery for us, so I sent a photograph to a friendly local expert on marine invertebrates, who said that these were the cocoons of the Pacific lugworm. Lugworms can live at quite high densities in the sediment, each one in a J-shaped burrow. They feed on detritus from the surface of the sediments; in the process, they take in a quantity of dirt as well, which is eliminated in long thin coils (which observers often see on the surface). We happened to be on the beach during the reproductive season, and females had produced these cocoons of babies, each one attached by a thin string to the mother’s burrow. According to research reports, males produce packets of sperm, which get washed over the surface of the sands to a female’s burrow, where the packets break open, releasing the sperm to fertilize the female’s eggs. The eggs are brooded in cocoons by the female either in her burrow or, in the present case, tethered to her burrow. When the young emerge from the cocoon, they are little wormlets that forage over the sediments near the surface.

I’m looking forward to our next ‘treasure hunt’!

Purple mountain saxifrage

a hardy flower and a spring delight

One of the earliest flowers to appear in spring is purple mountain saxifrage. In April some of us make a point of regularly checking certain places where we know it lives, just for the pleasure of watching for the first open flower and then the appearance of more and more blossoms, until there are multiple patches of the pinkish-purple flowers on some of the local rocky outcrops.

purple-mountain-saxifrage-on-April-10-2013-at-Nugget-Falls
Photo by Bob Armstrong

This low-growing plant occurs in Arctic regions around the world, and in alpine areas of central Asia, Europe, and North America. It’s a tough little plant, quite resistant to drought and water-stress. It forms associations with mycorrhizal fungi that provide nutrients and water, in exchange for carbohydrates produced by the saxifrage leaves. As with several other early-season bloomers, the flower buds are actually formed the year before the flower opens, but eggs (in the ovary) and sperm (in pollen) don’t develop until spring.

Female parts of the flower mature before the male parts do, which reduces the chance of self-pollination (pollen fertilizing future seeds in the same flower). Most seeds are produced by out-crossing (pollen fertilizing future seeds on a different plant).

The flowers are pollinated by insects of various sorts, including bees and flies. Early in May, we watched a female margined-white butterfly visiting one flower after another, so presumably there are minute amounts of nectar therein. These insects don’t see the longer (reddish) wavelengths, so they see the flowers as bluish. However, studies have shown that seed production is often limited by low levels of pollinator activity, perhaps in part because bad spring weather sometimes reduces insect activity. In addition, one study showed that as soon as other flowers started to bloom, insect visitation to the saxifrage decreased, as the insects found preferred sources of food.

This is an ecologically variable species, with different types adapted to different conditions of soil, snow-melt, length of growing season, and so on. For example, one study showed that the plants growing in cold, wet soils with late snow-melt had higher metabolic rates and faster production of shoots than those in warmer, drier sites, but they did less well at storing carbohydrates or water for hard times. In some areas, there are two growth forms that grow side by side but differ in structure (prostrate vs cushion-like) and in reproduction: one does better at seed production but the other excels at propagating by shoot fragmentation.

On the Old World Arctic tundra, purple mountain saxifrage flowers and old seed heads are eaten by barnacle geese when they arrive on the nesting grounds, and reindeer eat it too. I have not found information on animals that consume this plant in North America.

A word of caution: If you see this pretty plant in the wild, please do not remove it! That deprives lots of other folks of the pleasure of finding and seeing it in its natural setting.

Ralston Island

observations by amphibious naturalists

We left our camp on Lincoln Island in sunshine, with a following breeze. Arriving quickly at the wide beach on Ralston, we set out to explore the island. The trail marked on old topo maps proved hard to find, but a maze of deer trails made it easy to move around the forest. We wandered toward the north end of the island.

All along the way, I enjoyed the numerous flowering orchids. All had tiny, intricate flowers, rather than the showy ones that most folks notice. There were twayblades, named for the paired leaves on the stem. Darwin, long ago, figured out just how the little twayblade flowers contrive to be pollinated by visiting insects: when an insect touches a certain part of the flower, a sticky drop explodes outward, carrying pollen and sticking it to the insect, which carries it to another flower.

The most common orchid was one known as one-leaved malaxis or white adder’s tongue. A single leaf sits at the base of the flowering stem. There are no adders involved here except in somebody’s over-active imagination! We also noticed several rattlesnake plantains, which are not plantains at all. Nor do they have anything to do with rattlers, except that someone decided that the patterns on the leaves looked like snakeskin.

The most colorful ones were the pink coralroot orchids, which lack green pigment and so cannot synthesize their own carbohydrates. They are variously reported to be saprophytic (feeding on decaying organic material) or indirectly parasitic on other living plants by means of fungal connections. Ralston hosted some spectacular stands of this orchid.

As we strolled around, we saw no signs of red squirrels or porcupines, which presumably would have a hard time getting out there. Juvenile ravens were loudly making known their wants, as they tried to follow their harried parents through the trees. Songbirds still sang, even in late June; I heard song sparrow, hermit thrush, ruby-crowned kinglet; one hermit scolded us severely, using notes I’d not heard before, so we must have been too close to a nest or chick. A strange-looking woodpecker moved through the canopy; after checking the books, I guessed it was a hairy woodpecker—which are darker here on the coast than they are elsewhere.

The north end of the island was productive. There’s the densest, tallest stand of crabapples I’ve ever seen, and some of the gnarliest hemlocks. As we pushed through the brush toward a boulder shore, we stumbled into a small meadow, perched on a headland and sporting a surprising and lovely stand of wild iris. Out among the boulders we finally spotted some oystercatchers displaying to each other, apparently amicably. Later, we saw an oystercatcher vigorously and loudly chasing an eagle, which presumably had had designs on an oystercatcher chick.

Then it was time to head back to camp. Ah, but by now the tide had turned, not in our favor, and the headwind had risen noticeably. It seemed do-able, however, so off we went. Around the first point, things became more difficult: a stiffer breeze, a stronger tidal current, and there were also frequent, strong gusts of wind. We had to paddle hard and constantly, just to keep from going backward! In between those gusts, slow forward progress was possible, but it still took about four hours of nonstop hard paddling to get back to camp. Ooooofff!