The Pacific coast provides beach goers with amazing sites to
see. From the cliffs high above, to the tide pools down below, there is
something for everyone to enjoy. However, what many people overlook is the
hidden world of plants, insects, and parasites. Luckily for us, we have our
very own guide! Today we join George Poinar Jr. as he takes his grandchildren
down to the beach on an adventure to meet some of the plants and creatures
depicted in his new book, A Naturalist’s Guide to the Hidden World of Pacific
Northwest Dunes.
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Going down to the beach for a nature walk makes a fun
day. The kids are excited and
bring their pails for collecting shells, agates, bugs and anything else of
interest.
Chasing beach hoppers is always an attraction, especially
when these little crustaceans roll up in a ball and let the wind roll them down
the beach at great speeds. Watching the shore birds picking them out of the sand shows how
important beach hoppers are in the ecology of the strand, since they also help
decompose the seaweed.
With an especially heavy deposit of seaweed, the kelp flies are
swarming over the twisted stalks. Lifting up some holdfasts of Bull kelp
exposes the white fly maggots. Black
dots often cover the older kelp stalks. They represent miniscule springtails, so-called because these
insects have a spring that, when released, propels them quickly out of
sight.
There is also a wide range of life associated with
driftwood. Turning over some pieces near the high
tide line reveals ground beetles of all shapes and colors. Many were predators
that emerge at night to search for prey. Larger logs washed up onto the dunes
make wonderful homes for termites and beetle larvae. Some larvae take years to develop, but emerge as the largest
beetles in the Pacific Northwest.
There are always Sea Rocket plants. Notice their thick leaves that can
withstand the constant battering of sand grains and the seed pods that can float
in the sea for months and still germinate. Some caterpillars develop in the flower heads, but weave a
silken net around themselves to keep from being blown away. Another survival technique is to live
inside the leaves, like this little leaf-miner fly.
Further up into the dunes are the beautiful flowers of Beach
pea. There are several caterpillars that feed on its leaves but my favorite is one
that lives in the pods and relishes the seeds as much as we do garden
peas.
There is a small grove of coast willows that recently bloomed. Willows support so many different insects that they can be considered keystone
species. This little weevil develops on pollen inside the male catkin. Many
insects beside bees develop on pollen, which is an excellent source of protein.
The willow sawfly that forms red leaf galls is one of my favorites. The galls are formed when a chemical is introduced into a leaf by an ovipositing
sawfly. While the gall provides a
wonderful home for the sawfly larvae, they are not completely protected.
Parasitic wasps insert their own eggs into the galls and
their larvae dispatch those of the sawfly. Then there are beetles and caterpillars that patrol the
leaves, opening the galls and devouring the occupants. The complexities of life
surrounding these red willow leaf galls is amazing.
Piles of plant debris often turn out to be ant homes and you
can find red-headed dune ants scurrying all over them. Any animal that disturbs
the nests is at their mercy and the ants will rush out and bite the intruder,
at the same time spraying formic acid into the wound. The worker ants search for food and plant material and
bring back captured caterpillars in their jaws. These nests are a world unto
themselves since aside from developing ant stages, they are inhabited by
crickets, nematodes and a host of other creatures.
But dune ants do have their enemies. One ruthless predator is a little wasp
that cruises back and forth over the nest, waiting for the right moment when an
unwary ant is exposed. In a fraction
of a second, the wasp dive-bombs, inserts its ovipositor and deposits an egg
into the ant. The worker ant
continues to live for a while with the developing parasite inside, but eventually
dies.
These are just a few of the dramatic events that unfold in
the hidden world of the Pacific coast dunes.