Earlier this week I spent two hours at Florencia Bay in Pacific Rim National Park Reserve. Tide pool explorers familiar with better known locations like the rocks at Wickaninnish Beach, Green Point or Schooner Cove sometimes overlook this remarkable beach. Sometimes exploring less popular areas results in the discovery of unusual creatures like the lumpy crab!
Easy Access at Low Tide
I like Florencia Bay because access is easy and the intertidal zone is different from other locations in the national park. At Florencia, a field of large rounded boulders ranges in size from small chairs to love seats. Adding a few that are the size of small sheds creates a very interesting landscape and habitat. Most of the boulders are about mid-thigh height and surrounded by sand. This facilitates the opportunity to look for organisms without damaging other creatures.
Unusual Lumpy Crabs in Stone Pockets
While you’ll see many of the same anemones and sea stars that you find elsewhere, a careful search reveals other less common things. I examined a boulder and when I pulled the seaweed aside I noticed a small red crab nestled inside a pocket carved out of the stone. The lumpy red shell and round shape of this crab were characteristics that help identify it as a Pygmy Rock Crab (Cancer oregonensis). In addition, notice the hairy legs, also diagnostic for this species. The black tips of the claws are also a feature to look for (although they aren’t visible in these photographs).
Lumpy Crab Identification Features
Update: This crab is now correctly identified as a Lumpy Crab (Paraxanthias taylori). Heather Holmes at Parks Canada helped with the correction. Particularly telling is the fact that the tips of the claws probably aren’t black. It is difficult to see the claw tips because most of the crabs hide in the bowls in the rock. Looking at the close-up photograph below, notice the bumps on the cheliped. This is a diagnostic feature of the Lumpy Crab. In comparison, the Pygmy Rock Crab has smooth chelipeds. Because the lumpy crab is not listed in any of the common guide books (including Andy Lamb’s book) this led to a misidentification and learning opportunity!
Typical Habitat of the Lumpy Crab
The Pygmy Rock Crab is usually more active at night, emerging from its crevice or other hiding place to eat barnacles, snails, marine worms, bivalves and some green seaweeds. Males often have a harem of females and mate just after the female has moulted and its shell is soft. Apparently this crab will fold up its legs and roll like a stone when disturbed. Lumpy Crabs eat both green and red seaweeds as well as coraline algae. They live in the middle to low intertidal zone, often hiding in rocks and crevices (like Pygmy Rock Crabs). The crab that I found was so tightly wedged into its bowl that it was impossible to remove. The bowls are a very safe and protected space indeed!
This was my first look at a Pygmy Rock Crab Lumpy Crab. I’ll be definitely heading back to south end of Florencia Bay on the next set of good low tides in early August to see if I can find and photograph a few more!