Shoreline Outing Summary: Comox Peninsula Tip, June 5th. 2019

Hey Everyone,

We had 19 members and a little assistant show up at the very tip of the Comox peninsula. Some observations, follow ups and a species list can be found below.
A sluggish leopard
The spotted leopard dorid, Dialula odonoghuei was found affixed to the underside of a cobble. This distinctive nudibranch feeds on the sponges that encrust rocks in the middle-to-lower intertidal. How? Nudibranchs like their brethren the chitons and the gastropods have a specialized apparatus, the radula that can be used to rasp and file at their prey. In places, we saw extensive mats of a reddish-range encrusting sponge. The nudibranchs, chitons and snails are the ones hoovering up the algae and sponges that typically encrust these rocks. How can anyone determine what exactly is being eaten by the spotted leopard dorid? Patient observation by SCUBA-equipped biologists is one option, but another is to collect their fecal pellets and look at the collection of spicules, frustules, tests and the like to determine diet. This has been done for a southern relative of our local species, but never for Dialula odonoghuei. Any takers?
Chitons lined & mossy grazing with a furor that is insistent and bossy
There were a number of different chitons out along the shore. A number of them were members of the genus Mopalia, the mossy chitons, which has a fleshy girdle that encases a large portion of the mineralized valves or plates that are the distinguishing feature of the order Polyplacophora (many-plate-bearer). In Mopalia, the fleshy girdle, in addition to being extensive, is ornamented with large hairs and other odd bumps and spines. Locally, there are a number of species within this genus which vary from very hairy (Mopalia muscosa, the mossy chiton) to just vaguely so (Mopalia hindsii, Hinds’ chiton). Like most chitons, these species are deathly afraid of exposure in the light, thus their daytime hiding spots under the rocks. At night, they come out to graze. Tom Carefoot has put together a wonderful summary of research on the feeding behaviour of the genus Mopalia in our region. I pasted above a pie chart taken from his website (in-turn repurposed from a paper from the 1960s) that shows the gut contents on the Mossy Chiton, Mopalia muscosa. 
 
We saw a lovely juvenile lined chiton of the Genus Tonicella. This genus diverse in our area, but easy to recognize by its dramatic, bright colors and linear patterns. We saw an example of one of these small juvenile chiton rolling up such that its vulnerable undersides were abutting one another, with the plated surrounding the entire enrolled individual. This is presumably a protective response. The main predators of chitons in the intertidal are purple sea stars (Pisaster ochreus) and a potpouri or birds, fishes and otters. Hard to imagine this defense being of any help to the smaller individuals, though the birds might appreciate the more streamlined bolus it provides.
Northern Kelp Crab Fashion
Group member Barbara could not help but marvel over the giant living kelp crab that had a significant population of living barnacles on its carapace. So symmetrical was the arrangement that it could be mistaken for a thicket of regal hair. This kelp crab, Pugettia producta, is part of a grouping of crabs that includes a bunch of species known as “decorator crabs”. These crabs have a veritable menagerie of algae and invertebrates affixed to their carapace as a means of camouflage for themselves. The kelp crab is not known to decorate itself, but perhaps tolerates this kind of taxing load for the same reasons.
A good online guide to local-ish species
Kathleen was trying to make sense of some seaweeds and asked that this Central Coast Biodiversity website be sent out. The guide is good and visual and pretty comprehensive if not entirely specific to the central island. It makes a good reference Start with the species guide if you are trying to figure out the identification or something. You can usually follow it through and learn a little about the biology, ecology and distribution.
Species List
As mentioned, observations are now being kept in iNaturalist. You can see pictures and IDs (at varying levels of confidence and resolution) here. I am also pasting a species list below, though I was not able to keep track of everything yesterday on account of so much being seen and so many people seeing it. If you have additions, corrections or deletions from the list, let me know.
Name Common Name
Seaweeds
Sarcodiotheca gaudichaudii
Succulent Seaweed
Lithothamnion Encrusting Coralline Algae
Hildenbrandia Encrusting Red Algae
Sargassum muticum Japanese Wireweed
Family Ceramiaceae Filemntous Red Algae
Chondrus Irish Moss
Ulva Sea Lettuces
Fucus distichus Rockweed
Leathesia marina Sea Cauliflower
Neorhodomela larix Black sea pine
Sponges
Homaxinella amphispicula
Dead Man’s Fingers
Ophlitaspongia pennata
Red Rock Sponge
Urchins
Strongylocentrotus Purple/Green Sea Urchin
Sea cucumbers
Cucumaria miniata Orange Sea Cucumber
Eupentacta quinquesemita
Stiff-footed Sea Cucumber
Sea stars
Dermasterias imbricata
Leather Star
Pisaster ochraceus Ochre Sea Star
Order Ophiurida Brittle Star (Daisy?)
Bivalves
Tresus Gaper
Chlamys Scallop
Nudibranchs
Diaulula odonoghuei Spotted Leopard Dorid
Aeolidia Shaggy Mouse Nudibranch
Anemones
Anthopleura elegantissima
Aggregating Anemone
Metridium Plumose anemone
Urticina Red Anemone
Chitons
Mopalia ciliata Hairy Chiton
Mopalia muscosa Mossy Chiton
Tonicella Lined Chiton
“Worms”
Serpula columbiana Tube worm
Order polycladida Flatworm
Family Terebellidae Spaghetti Worms
Nereis sp. Clam worm
Family Polynoidae Scale worm
Bryozoans
Schizoporella No common name
Bugula californica Spiral bryozoan
Crabs
Cancer productus Red Rock Crab
Petrolisthes eriomerus
Porcelain crab
Lophopanopeus bellus
Black claw crab
Pagarus grainosimanus
Grainy Hermit Crab
Hemigrapsus nudus Purple Shore Crab
Hemigrapsus oregonensis
Green Shore Crab
Pugettia producta Northern Kelp Crab
Fish
Oligocottus maculosus
Tidepool Sculpin
Gobiesox maeandricus
Northern Clingfish
Anoplarchus purpurescens
High Cockscomb
Porichthys notatus Plainfin Midshipmen
Family Cottidae Green Tidepool Sculpin
Plants
Galium aparine Catchweed Bedstraw
Spiraea Spiraea
Ambrosia chamissonis
Silver Beachweed
Zostera marina Eelgrass
See you soon,
Randal
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