The Knitting Nurse

Rambles and Travels

Things You Find on the Beach – Part Two – Tide Pools

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How I love beach-combing.  Here are more objects to share from a walk on local North Beach.  A minus tide day, unfamiliar pools offered themselves up for exploration.

I believe this bone is a femur from a marine mammal, a seal perhaps. A smaller version, nearly identical in form, I found down in CA.  There are just a few scrape marks on one if its ends.  A critter briefly got it’s maws on it.  Sorry for the blurred photo. My large, man-hands lend it scale.


GIANT ACORN BARNACLES:  Prolific, these crustaceans keep near low tide line, adhering to pilings, rocks and even each other.  Early peoples of the PNW used them as a food source. Its self-built outer plates are armor.  A hand-like projectile called a CIRRI exits  the opening and catches food. When the animal dies, it’s shell becomes a home for other organisms such as crabs and sculpins.


Two shells:

(Top) LEAFY THORN PURPURA:  This snail’s  vertical “frills”  grow in proportion to the roughness of the seas it calls home. The rougher the water, the smaller the frills to prevent excess tossing and turning about.  How’s this for adaptation – if flicked up by a hungry fish, the frills help keep the shell from landing opening side up and exposing the snail inside.  Cool, eh? It eats bivalves and barnacles.

(Bottom)  Not sure what this is.  Anyone know?


MOSSY CHITON:  Thick, bristly hairs ring a line of plates that articulate.  Tubeworms, algae and barnacles sometimes make its back a home.  Keeping close to the inter-tidal line, it will hunt mostly at night and tolerates low salinity water (sometimes heading into estuaries.)   This Chiton prefers a meal of sea stars.


AGGREGATING ANEMONE: This one’s opened its tentacles.  When closed, it looks like a green blob of goo.  Aggregations, or colonies are formed by one anemone that’s cloned and repeatedly divided.  Fascinating.  Lines of demarcation tend to separate colonies.  Anemones not belonging to a colony grow larger than those in one.  Tiny algae lives inside the anemone’s soft tissues giving it a green hue.  Small crustaceans and organisms fall prey to its stinging tentacles.




Since we’re on the topic of tide pools, let’s talk about tide pool etiquette.  I’d like to stress that when I sleuth about, I keep my hands out and do not disturb the organisms in there.  Some guides suggest you can in a gentle manner.

I choose not to.

Visit places quite popular and you can see the damage enthusiastic, touching hands can do.  Oils from our skins (natural and from sunscreen) harm the critters.  Dislodging them can expose some sensitive ones to harmful light. Turning over rocks and leaving them that way may kill the animals living on its underside.

Here’s a neat little guide from the Monterey Bay Aquarium including directions for a homemade underwater scope. 

Olympic Coast National Marine Sanctuary offers tips for low-impact tide pool exploration.

A list from WA Trails Association on etiquette and locations worth visiting.


Enjoy exploring the inter-tidal zone.  I think I may make that underwater scope.

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