Sunlight penetrates the mouth of an intertidal cave, illuminating the goose-neck barnacles within. The morning rays particularly light up hemoglobin in the barnacle’s blood.
Lamb and Hanby (2005) make quite a deal about the glorious red blood of Nakwakto goose-necks from Slingsby Channel, British Columbia, Canada. The striking blood of Nakwaktos is visible, supposedly, because this subtidal form lacks the protective black pigment present in intertidal populations that experience sun exposure.
Let’s compare. The photo below shows typical Pollicipes on exposed rocks near the cave on the same morning.
Are my cave-dwelling Pollicipes all the more magical in the morning because they lack protective pigments?
Lamb, A. and B. P. Hanby. 2005. Marine Life of the Pacific Northwest. Harbour Publishing.
Note: While I was researching this phenomenon, I noticed that the Biodiversity of the Central Coast’s Pollicipes page shows images of red goose-neck barnacles from a sea cave on Calvert Island. Biodiversity of the Central Coast is a great site. You should keep it on your intertidal radar.