I’m glad that a few photographs turned out from my weekend trip to Vancouver Island. Otherwise, I’d be even more cross at the one hour delay for one ferry (on the way there) and the four and a half hour delay on the way back. I didn’t get home until 4 AM Monday morning; 4 AM was also the time I started on Sunday to reach Botanical Beach at low tide, the site of today’s photograph.
Sea sacs are an algae of the intertidal zone, the area between the high tide mark and the low tide mark. The narrow band of the intertidal requires its inhabitants to have developed a number of strategies or structures to survive in this harsh area; mechanical pounding of the surf, temperature and moisture fluctuations and salinity variability are just a few of the conditions requiring special adaptations.
As noted in this essay on Halosaccion glandiforme, one adaptation of this alga to live in the intertidal is its gross morphology. The short, tubular shape of sea sacs helps to prevent damage from churning water. A second adaptation is the ability of sea sacs to retain water internally in the sac, moderating the extremes of temperature and moisture that would otherwise be experienced by the organism.