Monday, September 27, 2021

Eccentric Sand Dollars and Blood Stars

On 25 September 2021, Erika and I took a spur-of-the-moment drive to Westport on the Pacific Ocean. The day was sunny and warm, with the weather forecast being for rain during the upcoming week. We do not have too many creatures to report—but any day at the beach is fun. We ended up walking along the beach, seeing little besides two Echinoderms—aka starfish. The first is probably an Eccentric Sand Dollar, Dentraster excentricus, found from Alaska to Baja California—eccentric because the pattern on the back is off-center. My understanding is that this species is the only one found in Washington and Oregon. The starfish may be a Pacific Blood Star—that is my best guess. These starfish is rebounding from near extinction from an unknown wasting disease that struck several years ago. They occur from Alaska to Mexico. Although Echinoderms show considerable variation, all are basically pentaramous, a trait they share with us Chordates. That trait along with aspects of their embryonic development indicate that, among the animals, echinoderms are our not-so-distant evolutionary cousins.

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