Friday, August 22, 2014

Tidepool Explorations: How To

Tidepool:  n, a pool of water that is left in a depression in the rocks after the tide has receded; v, the act of exploring a tidepool.  "I'm really looking forward to going tidepooling out in Harpswell at low tide."

Tidepools are places where we humans -- such a wimpy species really -- can get a glimpse of what lies below the surface without putting on special wetsuits and masks and snorkels.  These little outposts of the ocean are amazing places to poke around and find treasures of the sea -- seaweed, snails, seastars, urchins, fish, crabs and lobsters, and anemones.  Maine, I am happy to say, has its fair share of tidepools, and I encourage you all to get out there and poke around in them.  As a tidepooler from way back, I thought I'd share some tips for how to best explore one of the most fascinating habitats in Maine.

Really, does it get any better?
Go on a spring low tide.  Not all tides are created equal.  When the earth, moon, and sun are in alignment, tidal amplitude are at their greatest -- we have higher highs, and lower lows.  These are called spring tides (but do not occur during the spring season alone; the name is due to the tide "springing" up and down).  You can find out when the lowest tides are by looking at a tide chart.  Tide charts include information on when low tides are, and also how low each tide is.  For example:

This is a tide chart I just pulled up from here.  You can pick a harbor near you, and get tides for any month of the year.  For each date, the chart tells you when low tide is, and lists its size compared to the average low tide (see the "ft" column?).  The average low tide is calculated by collecting tidal data over 19 years (why 19?  You got me!) and then each tide is predicted based on this data.  So the lowest tide of the month was on August 12, at 6:40, when the tide was a whole 1.7 feet lower than average -- a very low tide.  This is when parts of the intertidal are exposed that you don't get to see on just any old low tide!  But the low tide on the first of the month, occurring at 9:32, was higher than average, so you wouldn't get to see much at all (also, it would be dark). So if I were to pick a great time to explore a tidepool, it would be August 12, starting at about 5:30 -- well before low tide, so the tide's going out.  That would give me plenty of time to poke around.

Extraordinary tidepools at Giant Steps.
Wear appropriate shoes.  You're going to get wet in the rocky intertidal, the water's going to be cold, and there are lots of things that can cut up your feet.  I like to wear wellies (tall rubber boots) when I head out to the tidepools.  If you're looking for a pair of rubber boots, I can recommend Dunlops.  They're ugly, but they last and last.  You're likely to see fishermen up here wearing them -- as good a recommendation as I can imagine, and the reason I got mine.

A student exploring in her wellies.
However, other people prefer to wear dive booties.  They let you go deeper into tidepools than boots (I have a definite limit on how deep I can walk into a pool).  Your feet will get wet, but the neoprene will insulate them pretty well.

Professor Amy Johnson, my partner in crime here at Bowdoin, likes to wear dive booties.
If neither of these options are for you, I recommend either a pair of Keens or an old pair of sneakers you don't mind getting wet.  Whatever you do, don't try to go barefoot, and don't wear flip flops.  That's just asking for trouble.  Happy feet will make you a happy explorer.

Acorn barnacles, lying in wait to cut up your feet.  Careful!
Be careful.  BE CAREFUL!  Of all the things I worry about when I go out to the ocean, it's waves that are the scariest.  Water has a lot of mass -- it weighs about 8 pounds for every gallon.  That makes it dangerous.  Waves can, and do, knock people off their feet, and can sweep them out to sea.  It happens almost every year here in Maine.  Folks go down to the shore to watch a big storm, get too close to the edge, and a big wave comes along and carries someone to their death.  Like I said:  BE CAREFUL.

It's best to visit tidepools during very calm conditions.  If there are any waves, stay on shore and just be awed by the ocean's power (from afar).  When you're near waves, don't turn your back to them -- face them so you can see them coming.  And finally, realize that not all waves are the same size.  Waves vary in size, and every once in a while a big one comes along.  Don't trust the ocean, ever; she will trick you!

Waves bad . . .
. . . calm good.

Bring a bucket!  There are lots of things you'll want to take a closer look at.  Buckets can be very useful for setting things aside so you can investigate them further.  Just remember, organisms need to be returned to the exact spot they came from, and you can't collect intertidal organisms without a permit.

You can get nice big buckets at hardware stores.
Wear your sunglasses.  Your polarized sunglasses, that is.  They cut down on glare and allow you to see under the surface much more easily than without them.  Going when there's no wind, and therefore no waves, makes visibility even better.

Investigate, ask questions, and go ahead -- touch carefully!  There are very few things in tidepools I won't touch.  Most organisms are more likely to be hurt by you that you are by them. As you probably know, some things pinch.  But most things are harmless.  Sea stars, urchins, snails, mussels, seaweed, and fish are unlikely hurt you.

Seastars are most common very low in the intertidal.
You might find this guy if you turn over a rock!
Or this guy -- a rock crab.  Careful of the pinchy parts!
Sea urchins in Maine are not poisonous.  Go ahead, touch!  See his little tubefeet?
What a great find!  A seastar who has lost all his legs but one.  He'll grow the others back if he's lucky.
A rock gunnel.  Slippery devils, but really cool.
A predatory dog whelk and egg cases from dog whelks, found under a rock.
One of the things you definitely want to do in a tidepool is (carefully) turn over rocks.  That's where the cool stuff likely to be.  What might you see?  Crabs, lobsters, rock gunnels, and urchins all love a good rock to hide under.  Just be careful that you don't crush any organisms when you put your rock back (and put it back just the way it was).

My final word of advice on investigating is to take your time and truly look.  I find a lot of things by working very slowly.  Few observations worth making are quick.  Spend several minutes just wandering around a single pool.  You never know what you'll find!

Take some useful resources.  I really like the following books:

The Naturalist's Guide to the Atlantic Seashore (Scott Shumway)

The Seaside Naturalist (Deborah Coulombe)

Life on Intertidal Rocks (Cherie Hunter Day)

Peterson's Field Guide to the Atlantic Seashore (Kenneth L. Gosner)

A tidepool in winter.  That's advanced tidepooling!
Next week:  Tidepool Explorations: Where to


  1. My grandson Dustin loves exploring the pools (gotta admit so do I)..barnacles..our equivalent to a coral reef and the effect on bare feet...

  2. Great shots! And good tidepooling advice as well. As for the 19 year remark on the tide chart discussion - per this site, , it takes 19 years for the inclination of the moon to cycle - probably the reason that the average low is calculated over a 19 year period.

    1. Logical! I've always wondered about that.

  3. Helpful link sunrise/sunset times, high/low tide information for good fishing, This website has really good tidal data