Friday, May 12, 2017

Extreme Low Tide: Sand Dollar Tracks and Moon Snails

My job the other day was to assess the geology hazard at a very steep and high shoreline bluff. From the top of the bluff there was not much to conclude regarding the underlying geology. All I could ascertain was the upper bluff was too steep and too high to descend.

No way down

There was no way to see any of the bluff without taking a long beach walk from a better access point. The timing of the visit was very good with sunny weather and a very low tide which pulled out well beyond the local mean low tide.

There were plenty of good geology exposures along this steep bluff, but on my return walk I took some time taking in the marine life far out on the sandy tide flats.

Sand dollar pile up

Sand dollar making tracks

Sand dollar track across ripples

During my walk I came across several of these odd odd shaped objects on the tide flats:

The objects are rubbery with sand embedded in them.

And yes bare foot field work is great

Then a bit further on I found the responsible animal.

This large snail is Euspira lewisii or moon snail. The snail happened to also be April's Critter of the Month (eyes-under-puget-sound-critter-of-month.

The sandy rubbery casings I was seeing are egg packages and I happened to get lucky and saw an egg package being just released. The moon snail is a predator and eats clams by boring through the shell. 

1 comment:

Hollis said...

The sand dollar tracks and egg package casings are very cool ... lucky you!