The Rocky Intertidal of San Juan IslandBelow: Cattle Point at low tide
Cattle Point is a rocky shoreline on the southernmost tip of San Juan Island, jutting into the Strait of Juan de Fuca. This part of the island receives the most wave action, with debris and driftwood often washing in with the current.
Cattle Point is one of the driest areas on San Juan Island, receiving only 19 inches of rain a year. The Olympic Mountains to the west are in part responsible for this aridity; these 7,000-foot snow-covered peaks create a rain shadow that provides a moderate, sunny climate for much of the year. The grasslands on the bluff surrounding the lighthouse have adapted to this windy dry area.
As you descend the bluff toward the ocean, you'll notice bleached logs high above the intertidal zone, carried in by storm surges. Two intertidal habitats are found at Cattle Point: rocky cliffs and cobble beach. The steep descent means space is at a premium here; animals must compete for a place to feed, to reproduce, and, for some, to move about. There are transient visitors to this environment that can come in with every tide: sculpins, gunnels, and other fish threaten the existence of many resident invertebrates. Most animals have developed defenses to keep out of harm's way in this dynamic environment. The decorator crab has one of the most elaborate covers--it gathers up other animals and algae and cultivates them on its back.
Tidal exchanges at Cattle Point average about 12 feet, with more than a hundred feet of intertidal area exposed for the high tide mark to the low. In this area, surge channels, vertical walls, crevices, and tidepools hold a great abundance--and diversity--of invertebrates. As you explore the intertidal region, don't forget to look up from the tidepools and crevices. Harbor seals, orcas, and Dall's porpoises can be seen offshore. Up above, black oystercatchers, pelagic cormorants, and bald eagles can be seen.
Click on the map to visit a Cattle Point habitat
(or choose a link below):
- High Intertidal Pool
- Handy Joe's Crab Den
- Barb's Wet Channel
- Barnacle Wall
- Lindsey's Crevice
- Owen's Weed
Featured Organism: The Decorator Crab
Approaching Cattle Point
The Wet, The Wild and The Latin