Low Tide Meander

Hermit CRab

When the weather prevents snorkeling, there is still ocean life to see.

The difference here between low tide and high tide is one foot, yet it exposes twenty yards or so of seafloor.  If these were the extreme tides like they get in Alaska (twenty feet), I might be able to walk to Cuba at low tide. Or at least to the Florida reef.

The winter Florida sun is hot, but the persistent breeze is cool.  On the news, the breeze warranted a “gale warning,” but I’m from the Windy City, and there’s no snow here, so it’s just a summer breeze to me.  When the tide was out, I went tide-pooling, or just wandering through ankle-deep water, to see what lies beneath the sea.  Same difference.

The Florida Keys formed on an ancient coral reef exposed at the end of our most recent glaciation when the sea level here dropped 350-500 feet.  Sand built up, plants took root creating soil, limestone was eroded and redeposited, and the Keys were formed.  So it’s not surprising that there isn’t a sandy bottom here.  There are pockets of sand here and there, but it’s mostly limestone and coral rock. I wore my Teva sandals to protect my soft feet from the sharp edges…and shells…and crabs!  It was the crabs that made me go back to my room to get my iPhone.  (All of the images in this post were taken with it proving that you don’t need “fancy equipment” to make compelling images).

The limpets are, by far, the most common animal I see. When the tide is in, these tiny mollusks are underwater behaving like snails.  When the tide goes out, they use their muscular foot to lock themselves to the rocks. This keeps them from drying out, being eaten by shorebirds, and being pried off by people.  It is a tight, tight seal.


Limpets and their trails

Next are the hermit crabs – in every size.  As they grow, they need to find sequentially larger and larger shells to call home. All of these tiny crabs were clamoring about a big, empty conch shell – kind of like ogling houses on Zillow…but for crabs.

Big dreams: how many little crabs can you see here clustered around that huge empty conch shell?

I fell in love with these shimmering plants. Their structure reminds me of mushrooms.  I learned that they are large single-celled algae wonderfully named Mermaid’s Wineglass.Tide pooling

Someone out in the Straits of Florida is making a good living on horseshoe crabs, which are not really crabs at all but more closely related to scorpions and spiders. There are several of their empty shells washed up along with a surprising number of sea sponges in the mound of seaweed that marks the high tide line.

Sometimes I stumble across things that make me gasp with delight.  I picked up this can (because I pick up and dispose of garbage when I wander) and gasped at what I saw.

It’s clearly shark-bitten!  The shape of the bite, the arrangement of the tooth punctures give it away.  I can understand why a shark would think this silver shimmery thing in the water was a fish.  Imagine her disappointment.

There are occasional dead mangrove trees still standing, a reminder of the 185 mph sustained winds of Hurricane Irma in 2017.  They anchor in the rock, provide substance for further limestone and sand deposition, and could be the start of a new islet.

What a beautiful way to spend a winter afternoon.

Tide pooling
The view from the beach


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6 Replies to “Low Tide Meander”

  1. You make geology so much more interesting to me than back in school. To see the pictures when you describe the formation of the Florida Keys followed by all sorts of life there in the shallows and tide pools makes it real in my mind now. Glad you managed to find life as fascinating as ever regardless of the weather you were dealt.

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