Exploring Rocky Shores of Southern Oregon Coast

SEA STARS

Sea Stars, formerly referred to as "starfish", belong to the phylum Echinodermata, and all have the following characteristics:

• Multiple arms (5-24)
• Hundreds of tube feet per arm
• A central disk
• A madreporite (a perforated plate), the noticeable white spot on the top side of the central disk, through which water is pulled into the star's internal water-vascular system
• Small eye spots at the end of each arm, capable of distinguising between light and dark
• The mouth is located on the underside of the central disk

NUDIBRANCH

Nudibranch (pronounced NEWD-i-brank) belong to the phylum Mollusca, and the class Gastropod. They closely resemble snails without shells (nudibranch translates as "naked gill") and are often referred to as "sea slugs"...a name I particularly detest. Nudibranchs have several common characteristics:

• They are usually very small, many only an inch long
• They are often boldly colored, a warning to potential predators of their foul taste and/or poisonous stings
• They have two rhinophores (antler-like appendages) at the front of the body, used to detect the scent of potential prey. These vulnerable rhinophores can be retracted into a pocket beneath the skin when the nudibranch senses danger.
• They breathe through an exposed gill structure, which helps to idenitfy to which order they belong: Dorids have a plume of gills at their anus.  Eolids have finger-like appendages all over their backs called cerata.
• They are carnivorous and eat anemones, bryozoans and sponges
• They only live a maximum of one year

CHITONS

Chitons (pronounced KY-tun) belong to the Phylum Mollusca and the Class Polyplacophora.  Because they curl into a ball whenever dislodged or pryed off rocks, chitons have been nicknamed Sea Cradles.  Chitons have several common characteristics:

• They have no distinct head, nor do they have tentacles or eyes
• All have 8 over-lapping, articulated (i.e., joined segments that are flexible) shells that allow the chitons to bend their bodies to conform to the rocky surfaces and crevices where they eat and live
• All have a single muscular "foot" for crawling and clinging securely to rock surfaces
• All feed on algae by scraping it off rocks with their radulas, a file-like rasping "tongue" embedded with metal oxide
• They move about and feed at night when they are less vulnerable to predators, such as birds

Ochre Star

The most common sea star (they aren't called starfish anymore!) on the southern Oregon coast is the Ochre Star (Pisaster ochraceus), which can be spotted from a distance due to their bright colors, relatively large size, and the fact they live near the low-tide line on exposed rocky shores.

All sea stars have hundreds of tube feet located  in two rows on the underside of each arm.  Stars use these tube feet for locomotion and to capture prey. In the photo below, a few tube feet are visible (the fine white threads extending from star's far-right arm) attached to the shell of a mussel, the Ochre Star's favorite prey.

 

Biologists have recently discovered a pair of "duo-glands" at the tip of each Ochre Star tube foot. One gland secretes a "glue" allowing the star to adhere to a rock indefinitly, or pry apart prey. When the star is ready to move about or finished consuming its' prey, the second gland secretes a substance that dissolves the "glue."

Sea Stars have the ability to regenerate a new arm(s) when they lose one or more to predators or mishap. In controlled experiments, biologists have been able to regenerate five complete, new sea stars from the five severed arms of one Ochre Star.

Troschel's Sea Star

Troschel's Sea Star (Evasterias troschelli), also called the Mottled Star, resembles an Ochre Star, though the Troschel's arms are much more slender and its' central disk is much smaller.  Also, the whitish spines on Troschel do not form a pattern as they do on the Ochre Star.

 

Please note the round white spot near the center of the central disk (photo below). This perforated plate is called the "madreporite" through which water can be taken into the sea star's body and pumped through its water- vascular system.  The water-vascular system is connected to the star's tube feet and its' ability to move about the tide pools and capture prey.

A sea star's mouth is located on its underside.  To eat, the star extrudes its stomach through its mouth and wraps it into or around its prey. The stomach is thinner than a piece of paper and can be inserted into the tiniest of openings to digest a mussel or other bivalve.  The star digests its' food externally before swallowing it.

Leather Star

The Leather Star (Dermasterias imbricata) has smooth, slippery, leathery skin on its upper suface, hence its name.  If you find a leather star NOT attached to rocks and can pick it up without damaging its' tube feet, turn the star over and smell the mouth...there will be the faint whiff of garlic breath!   All my reference books say a leather star can grow to 8" in diameter, but the one we found at Sisters Rocks (below) in the summer of 2010 was closer to 10"...absolutely huge!

Leather stars are carnivorous (as are all sea stars) and feed on sea anemones, sea urchins and sea cucumbers.  Judging by the photo below, the leather star may be attempting a lunch of Giant Green Anemones...though in this case, his eyes may be bigger than his stomach! A leather star will put its arm on top of a sea anemone to determine how large it is.  If the anemone is too large, the leather star will move on to another, smaller anemone.

The Leather Star's tube feet are clearly visible in the photo below (the white spikes projecting from the cream-colored underside of the star's arm), as well as its white eye-spots at the end of each arm.  All Sea stars have these "eyes", and while they can't see clearly, they are able to distinguish between light and dark.

Stimpson Sun Star

The Stimpson Sun Star (Solaster Stimpsoni) is usually found only at the very low-tide line, and it is thrilling to find one of these rare beauties.  We found this Stimpson Sun Star north of Gold Beach at Sisters Rocks. It is a voracious predator and its favorite prey are sea cucumbers. The Stimpson Sun Star typically has 10 arms, and can grow up to 20" in diameter. This speciman had 11 arms but was only 10" in diameter.   What it lacked in size, it more than made up for in its spectacular coloring!

  

 

We found our first Stimpson Sun Star in 2007 (below) with its arms wrapped around a sea cucumber....its favorite meal.  This one wasn't nearly as colorful as the one we recently spotted (above), but it did have the signature bluish-gray lines down each arm.

Blood Star

Even though the small Blood Star (Henricia leviuscula) grows to only 3-4 inches in diameter, its shocking red color makes it highly visible, even from a distance. 

The Blood Star feels very leathery to the touch, and can often be found hanging off a rock by only one or two arms. 

We have only found Blood Stars in protected rocky areas covered with sponges and bryozoans..their preferred choice of meals. 

Sunflower Star

The Sunflower Star (Pycnopodia helianthoides) is the largest sea star in the world. They can grow to 40" across, and have up to 23 arms. The Sunflower Star below is appoximately 21" across and has 19 arms.  Sunflower Stars have  pedicellariae, tiny pincers that keep the skin free of parasites. If you rested the top of your forearm on the upper surface of most sea stars (not the Bat Star, Leather Star or Blood Star), the pedicellariae would "pinch" the hair on your arm and you would definitely feel a pulling when you removed your arm.

 

The Sunflower Star, like many other species of sea stars, comes in a spectrum of colors including yellow, orange, gray, blue and purple. The most prevalent color of Sunflower Stars on the southern Oregon coast is a reddish-purple, like the one pictured below. 

Sunflower Stars move very fast compared to other sea stars and can move as fast as 5 feet a minute.  They have voracious appetites, and no intertidal animal is safe when the Sunflower Star is nearby! In the photo below, please note the white hair-like tube feet extending from the stars' upraised arms, with which it captures its prey.

 

When you touch a Sunflower Star under water, the skin feels like wet fleece...very soft and mushy.

When a Sunflower Star is stranded on rocks or sand above the tide line, it dries out, becomes desiccated, and is gelatinous in appearance and to the touch (see below).  Desiccation is one of the potential hazards for stars and most other intertidal animals.

Sunflower Stars have only 6 arms when they are very young, and add arms as they age. The Sunflower Star pictured below has at least 15 arms, but is only 4-5" in diameter.

   

RED OCTOPUS

The Red Octopus (Octopus rubescens) can be found on the Southern Oregon Coast, but only at an extremely low-tide, in large tide pools or surf grass, and you have to be really lucky!  We have yet to spot our first octopus on the Oregon coast, but we are always on the look-out.

Back in April 2004 at the Fitzgerald Marine Reserve south of San Francisco, we had the tide-pool experience of a lifetime when we saw an octopus put on what looked like choreographed performance.  At first we saw only a couple of tentacles creep out from under a rock.

When he sensed we were near, he retracted his tentacles and his body became more bulb shaped.

He was caught in a small tide-pool, and seemed desperate to flee our prying eyes. He poked his head out of the water and looked around for a  means of escape.

In just a few seconds, we watched him begin to change color.

He also seemed to change texture to more closely blend with his surroundings.

At this point, he lunged out of the water and "slip-slided" across the kelp-covered rocks.

This is the last photo we took of him before he plunged into a surge channel and out of sight. The entire performance lasted less than four minutes!