A Few of my Favorite Things

Date: 5 September 2009
Who hiked: me
Hike route: Intertidal area of Isthmus Cove
Time: about 2:30 PM to 4:00 PM
Estimated distance: hardly any at all!
Weather: sunny and warm (low 80s)

Today I didn't really hike, but I did do a nature walk that I wanted to write up. I had been itching to do some poking about in the rocky intertidal areas of the local beach for some time. Low tide was at 4:30 and by 2:30 I had had enough of the Things and needed a break. Hubby was home from his SCUBA class, so I took off with our new camera, which just arrived on Friday.


I really like to explore the intertidal. It has a lot in common with one of my other favorite biological activities: looking for salamanders. Now those of you who know me will say, "But you have many 'favorite' biology activities." And you are correct -- I do! But one thing that I really like is the turning over of rocks. To find salamanders, you turn over rocks. It's like a grand treasure hunt... Sometimes there's nothing there. Sometimes it's a common species of salamander -- say a red-backed salamander -- which is always fun. But sometimes it's something really exciting, like a red salamander or a ring-neck snake.

The intertidal is a lot the same way. You don't know what you're going to see. Sometimes you lift up a rock or move aside a piece of algae and you find an anemone or a crab. They're great to look at or poke, no matter how many times that happens. But sometimes, you lift up the piece of algae and you get a sea hare!

So about today. The rocky area of Isthmus Cove is at its west end. The tide was not going to be particularly low -- only 1.0 ft above mean low tide height. But that is pretty good for the daytime low tides during the summer and we are on the full moon. I walked to the west end of the beach and began to climb out onto the rocks. The tide was already low enough to expose most of the aggregating and green anemones.

As I moved my way along the intertidal, I looked both high and low, but especially just above and below the water line. Diversity tends to decreases as one moves up from the water, because the terrestrial zones of the intertidal are so stressful to live in. It's a rough gig, trying to live in a habitat that experiences such variation in temperature, solar radiation, humidity, salinity, and tops that off with wave action!

I like to take my time and pick through areas in the intertidal. For example, it's fun to turn over a rock and try to count the hermit crabs, each no larger than a baby's fingernail, before they scurry away for safer harbors. I like to lift up the algae that is exposed at low tide. Organisms like to crawl under the algae, where it is cooler and wetter. Even if the top layers of the algae almost completely dry out, there are still usually critters underneath to find. Algae is remarkable in and of itself -- many intertidal species can lose extensive amounts of water, until they are dry and crispy, and then re-hydrate when the tide comes back in.

Today the rockweed that covers many of the rocks in this location was hiding a number of good organisms, including three sea hares. None were large -- the biggest was about the size of my pinky finger and the smallest probably about half that big. I got photos of one. These are herbivores that eat algae, especially a red alga (Plocamium). Their integument is velvety, touching one feels like stroking an over-stuffed suede sock.

Another species that I was excited to find was the ghost anemone, an introduced species from the East Coast. There is a small population of these anemones at Isthmus Cove. The largest individuals were the diameter of an eraser on a pencil!

Species observed today: California sea hare (Aplysia californica), Aggregating anemone (Anthopleura elegantissima), Green anemone (Anthopleura sola), Ghost anemone (Diadumene leucolena), owl limpets (Lottia gigantea), pink barnacles (Megabalanus californicus), acorn barnacles (Chthamalus/Semibalanus), other limpets, chiton, wavy top snails (Lithopoma undosum), Norris's top snail (Norrisia norrisi), hermit crabs (mostly Pagurus samuelis), unicorn whelks, scaled worm snails (Sepulorbis squamigerous), California mussel (Mytilus californicus), California cone (Conus californicus), Kelp lace bryozoan (Membranipora membranacea) -- on rockweed, rockweeds (multiple species), elephant snot (Colpomenia, red coralline algae, sea lettuce (Ulva)