Friends of Netarts Bay Watershed, Estuary, Beach, and Sea

Pisaster ochraceus
Ocher Star
Alaska to Mexico
Family Asteriidae
Native

The Ocher Star Pisaster ochraceus we see attached to rocks near Oceanside, sometimes huddled in groups just below the mussels. It comes in several colors ranging from bright yellow-orange, through brown, to purple. People exploring at low tide in the rocky areas near the mouth of Netarts Bay and along the tide pools near Oceanside seem to be drawn to these sea stars, sometimes called starfish though they are not fish, because they are large, showy, brightly colored. They belong to the phylum of invertebrates, the Echinodermata (Greek for prickly skin), that include sea urchins, sand dollars, and sea cucumbers. You will find these sea stars tightly attached to rocks, mussels, and to each other.

They usually seem stationary, locked in place. But they can and do move. They do this using a hydrostatic water-vascular system where water enters the animal through a porous plate on its aboral surface called a madreporite, which you can see on the top of the sea star because it is often colorful, and flows through a system of tubes that branch into each arm (ray) called the radial canals. Off each radial canal is a short lateral canal that feeds water into a tube foot. Each tube foot, and there are thousands of them, works like a tiny eye dropper. It has a muscular bulb at one end, called the ampulla, that regulates water pressure in the tube foot by contracting and relaxing, sort of like squeezing the bulb of an eye dropper. At the end of the foot is a sucker that can attach to surfaces like a suction cup. Coordinated movement of the tube feet allows for locomotion, or the sea star can just remain in place, stuck to a rock, held in place by its tube feet.

Pisaster ochraceus is a top predator. It will eat chitons, barnacles, and snails, but it likes mussels best. The most curious thing about this predator is how it eats. It does not ingest food as you and I do, but it feeds extraorally - that is, outside its body. An ocher star may venture into a mussel bed to grab onto a mussel or it may wait for mussels to be knocked off rocks by waves and drop into their grasp. When it decides to eat, it will then wrap its arms around a mussel, grab onto both shells with its tube feet and begin to pull the shells apart. As soon as the shells gape, even as little as a tenth of a millimeter, the ocher star will evert the lower chamber of its stomach (the stomach is divided into a lower "cardiac" stomach and an upper "pyloric" stomach), extrude it through its mouth, and slip it between the gaping shells into the mussel's interior. It then digests the mussel inside its own shells. When it is done feeding and the nutrients from the prey are absorbed, it will retract the stomach back through its mouth. If you see an ocher star with its upper side hunched up, it is likely eating. If you pry one from a rock and see a jelly-looking thing bulging from the center of its underside (its oral surface), that is its extruded stomach.

Around 2011-12, a severe disease, called the “sea star wasting disease”, hit all the seastars along the Pacific coast from Alaska to Mexico, in some areas wiping them out completely. A series of articles was written for our newsletter “Netarts Bay Today” regarding this devastating disease.

Tube feet

Feeding on mussel

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Pisaster brevispinus
Giant Pink Star
Alaska to California
Family Asteriidae
Native

A close relative to the Ocher Star is the giant pink star Pisaster brevispinus, common in the cobbles just inside the bay near Happy Camp and in the deeper channels of Netarts Bay. Colored a dusty pink, it has five thick arms attached to the central disk that can reach a span of two feet (60cm). It has aboral spines and pedicellariae. It feeds similarly to the Ocher Star but more likely on clams. If a clam is buried and the burrow is not too deep, it can extend the tube feet circling its mouth into the sand or gravel, latch onto the clam, and haul it to the surface. If it cannot get the clam out of its burrow, it can extend its stomach down to the clam to digest it in place. It will also eat snails, sand dollars, barnacles, polychaetes, and dead fish. The Purple Olive Snail will try to escape when confronted by this sea star. (See Pisaster ochraceus for more details on feeding and the action of tube feet.)

Pycnopodia helianthoides
Sunflower Star
Alaska to Mexico
Family Asteriidae
Native

With up to 26 arms, the Sunflower Star is the largest seastar on our coast, and one of the largest in the world, reaching a span of over three feet (one meter). It can be found near rocky tide pools and on sand and gravel inside Netarts Bay (see below). It is also most voracious and the speediest, moving up to more than two meters an hour.

The Sunflower Star is an opportunistic feeder and will act as either a predator or a scavenger. It seems to prefer dying or dead prey which are easier to get than live ones. It also an active sea star, so it has a large appetite. Besides bivalves, it eats barnacles, sand dollars, sea urchins, sea cucumbers, snails, dead fish, even dead birds. It also inverts its stomach to eat extraorally, but in addition, it will often swallow its prey whole. Large sunflower stars can excavate sediments and dig down to reach buried prey.

It can range in color from bright orange to solid purple, or as the one pictured here, multicolored. It can reproduce sexually by broadcast spawning or asexually by fragmentation, the splitting of the body either on purpose or by accident.

Around 2011-12, a severe disease, called the “sea star wasting disease”, hit all the seastars along the Pacific coast from Alaska to Mexico, in some areas wiping them out completely. A series of articles waswritten for our newsletter “Netarts Bay Today” regarding this devastating disease. The Sunflower Star was hit the hardest, and though once common locally, to my knowledge has not been found here since.

Asterina miniata
Bat Star
Alaska to Mexico
Family Asterinidae
Native

Rarely found here in the intertidal zone, Bat Stars will sometimes wash ashore from subtidal depths. While diving years ago in Northern California, I would see large patches of them decorating the rocky bottom in an array of colors from dark brown to cream, to orange, red, green, blue, and mottled. They live along the rocky, surf-swept outer coasts but are uncommon here. The Bat Star typically has five arms but may have from four to nine. The one pictured here has six. The arms have a “web” between them, inspiring the common name. It is mainly an herbivore and eats as do most other sea stars by everting its stomach. It has no spines and no pedicellariae but does have crescent shaped ossicles on its aboral surface, arranged with concave side toward the central disk. Its former name was Patiria miniata.

Dermasterias imbricata
Leather Star
Alaska to Mexico
Family Asteropseidae
Native

Uncommon between the capes but plentiful elsewhere along the intertidal and subtidal Pacific Coast, this is a distinctive sea star with its short rays, large central disk, and slick leathery aboral surface colored gray and rust. It’s a hardy predator, eating almost anything, but with a preference for anemones. Instead of inverting its stomach out its mouth, it swallows its prey whole and digest them internally. Many preys try to move away or exhibit some defensive response. Strongylocentrotus purpuratus, the purple urchin, retracts its podia (tube feet), depresses its spines, erects gapes its pedicellariae, then moves away. One other characteristic of this star is that is smells like garlic. It spawns in late spring and summer. It inhabits semi-protected rocky and sandy areas. It ca reach a size of more than six inches (15 cm).

Olive snail.
At low tide across some sand flats in Netarts Bay you may encounter meandering and crisscrossing trails of the beautiful little purple olive snail.
Click here for more information!

Aboral side

Oral side

Evasterias troschelii
Mottled Star
Alaska to California
Family Asteridiidae
Native

The Mottled Star lives mainly in lower intertidal areas of quiet protected waters rather than on the open coast, and this young sea star was collected in Netarts Bay on the rocks near the boat launch. It may also be found on sand. Evasterias can grow up to almost a foot (30 cm); this one was less than an inch-and-a-half (4 cm). It is often mistaken for Pisaster, but it has a smaller central disk. It feeds on bivalves, limpets, barnacles, snails, and tunicates by everting it stomach. It is eaten by gulls, and other sea stars. It frequently hosts the scale worm Arctonoe fragilis as pictured here.

The cream-colored object is the madreporite, a microporous structure that permits seawater to enter the hydrologic canal system that works the tube feet.

Evasterias can exhibit color polymorphism, the display of different color patterns, as shown here with two colored varieties.

Evasterias was severely affected by the sea star wasting disease of 2012-14. It is now recovering in Netarts Bay, but individuals are still small.

Leptasterias hexaxis
Drab Six-Rayed Star
Alaska to California
Family Asteriidae
Native

This small six-rayed star may be part of species complex, including L. aequalis and L. epichlora, also occurring in our region. The taxonomy has yet to be worked out. The Drab Six-Rayed Star grows to a little over two inches, is a predator and scavenger, and lives in the rocky mid to lower intertidal zones. They are common among the basalt cliffs and stacks of Tunnel Beach. They eat barnacles, limpets, snails, small mussels, chitons, and dead animals. They are winter and spring breeders, and the female broods her fertilized eggs and young around her mouth, which sometimes does not allow her to feed. Juveniles, when able, migrate away from the mother.

Mesocentrotus franciscanus
Red Sea Urchin
Alaska to Mexico
Family Strongylocentrotidae
Native

We have three intertidal sea urchins on our coast, and the Red Sea Urchin (formerly Stronglylocentrotus franciscanus) is the largest. The test (skeleton or shell) pictured here is five and a half inches (14 cm) in diameter, and its spines may have been more than two inches (5 cm) long. It inhabits the low intertidal to subtidal zones. Locally, it is found only along our rocky open coast, but it can also be seen in protected waters such as Puget Sound. The color of its spines ranges from brick red to deep wine to brown. It feeds on kelp and is common near kelp forests. It is a favorite prey of sea otters (which we have none around here), and is also eaten by sunflower stars, leather stars, crabs, some fish and humans.

In areas of few predators, populations may explode, eating all the kelp, forming what are known as urchin barrens. When diving in Northern California in the 1960s, I saw acres and acres of nothing but Red Sea Urchins. In 1972, a commercial fishery began, mainly for the roe (eggs) which were shipped mostly to Japan, although there was a small market in the US. When I revisited the same areas in the 1980s and 1990s, kelp forest had regrown where there were once only the barrens.

Red Sea Urchins are summer spawners. After going through a free-swimming larval stage, young urchins settle to the bottom, are attracted to adults via chemical cues, and hide under the larger urchins for protection. Red Sea Urchins can have long lives, up to 200 years with no signs of senescence, making it one of the longest living animals on earth.

Test of M. franciscanus. Diameter 5.5 inches (14 cm)

Strongylocentrotus purpuratus
Purple Sea Urchin
Alaska to Mexico
Family Strongylocentrotidae
Native

The Purple Sea Urchin, not nearly as large as the Red Sea Urchin, may reach three inches across, has short robust spines, and is colored a vivid purple. It is found on both the open outer rocky coast and in quiet protected waters from mid and lower intertidal zones to subtidal depths. Like the Red Urchin, it is a voracious feeder of kelp, using its five "teeth" (in an array called Aristotle's lantern) to bite off chunks of algae. It may also be carnivorous, eating mussels and barnacles.

Using its sturdy spines, it can dig shelter holes in solid rock, including basalt. The spines are movable, and though they are made of calcium carbonate which is softer than many rocks, their constant movement will gradually abrade the harder substrate. The spines do wear but are constantly regenerated. The spines are filled with anastomizing blood channels where calcium is carried to rebuild the eroded spines.

The urchin is motile using it tube feet much the way a sea star does. The tube feet also aid in respiration. For defense, it relies on both its spines and small toxic pincers called pedicellariae. These urchins spawn in January and February. Juveniles may be green.

The Purple Sea Urchin may be found in a deep tank-like tide pool on a large rock at Tunnel Beach.

Magnified cross section of a spine

Scanning electron micrograph of the outer edge of a spine

Strongylocentrotus droebachiensis
Green Sea Urchin
Alaska to Oregon
Family Strongylocentrotidae
Native

The Green Sea Urchin is roughly the same size as the Purple Urchin, but its color is a drab brownish green, and its spines are shorter and finer than those of the Purple Urchin. It is also a kelp feeder, but also eats coralline algae and diatoms. Its depth range is intertidal to subtidal (about 1200 meters). It is also present in the cold waters off Russia and in the northern Atlantic. It spawns during spring tides, often with many others, suggesting some physical signal that triggers mass spawning. The one pictured here is small, but they grow to about the same size as the Purple Urchin

Dendraster excemtricus
Western Sand Dollar
Alaska to Mexico
Family Dendrasteridae
Native

The Western Sand dollar Dendraster excemtricus, an Echinoderm and a close relative of sea urchins and more distantly of starfish, lives in dense beds in the quieter waters on the western side of Netarts Bay. More than a hundred individuals may occupy a square meter. There are also offshore populations of Western Sand Dollars that live just beyond the waves. While walking the sandy beaches between the Capes, we see many of the creamy-white shells of dead sand dollars, or tests as they are properly called, which are simply the animal's skeletons that have washed ashore.

Live sand dollars are covered with a short, rough "fur" of spines that help the animal move and feed. Individuals are flat on the bottom or "oral" side and domed on the top or "aboral" side where you will find a five-petaled flower-like pattern of pores, the ambulacra, through which extend appendages called podia that are used in respiration. The spines of the Netarts Bay sand dollars are mostly colored dark gray or black except those on the edge with the longest petal, which are light brown. It is this edge that is usually buried in the sand.

Dendraster feeds on detritus, organic particles suspended in the water or settled on the sand, plus small crustaceans or their larvae, and sometimes their own larvae. They capture and filter the food with their spines, then move it with their spines and miniature pincers called pedicellariae to food grooves on the oral side that lead to the mouth, the hole you see in the center of a test. They increase their feeding efficiency by burying their anterior edges into the sand, so they stand obliquely with their bodies parallel to the passing current. This enables them to influence the current and collect more food. When the sand dollars are exposed to air at low tide, they bury themselves completely by using their spines to push into the sand like little bulldozers until they are fully covered and are protected from the hot sun and predators, such as birds. Crabs, starfish such as Pycnopodia healianthoides, and finfish also feed on sand dollars. You may see individuals scarred by crabs that have pinched off pieces along their edges. Sand dollars can live to an old age of 15 years or more. You can find juvenile sand dollars in many parts of the bay.

Click here to see the video of live sand dollar tube feet.

Adults on edge

Juvenile about 1.5 cm across

Aboral side of test (shell)

Oral side of test

Apostichopus californicus
Giant Sea Cucumber, California Sea Cucumber
Alaska to Mexico
Family Stichopodidae
Native

Formerly, and often still, called Parastichopus californicus, the Giant Sea Cucumber, the largest sea cucumber in the Pacific Northwest, can grow up to 15 or more inches long and ranges in depth from low intertidal to subtidal. It is generally a brick red on its dorsal and lateral sides but has color variants ranging from white to almost black. Conical papillae or pseudospines decorate its dorsal side, and five rows of tube feet are on its ventral side. It crawls along the bottom ingesting organic detritus and small organisms that come along with ingested sediment by using twenty mop-like feeding tentacles. It is eaten by sea stars, sea otters, and humans. It can be found in the deeper channels of Netarts Bay.

It breaths by pumping water through it anus. The hind gut is highly branched with long diverticula, the respiratory trees or “water lungs”, that extend anteriorly. Water is pumped into the trees where oxygen is extracted. When disturbed, the Giant Sea Cumber can eviscerate its internal organs, including its “water lungs”, through its anus by rapidly contracting five longitudinal muscles that run the length of its body. This may be a defensive mechanism where the expelled guts serve as a decoy to predators. The lost organs are regenerated.

It breeds in the summer. Sexes are separate. The broadcast egg and sperm unite to produce a free swimming auricularia larva, a larva with a curving girdle of cilia typical of echinoderms, which then changes into a doliolaria larva that settles to the bottom.

There are small commercial fisheries for this sea cucumber. It’s particularly found in Asian markets. I have eaten the five longitudinal muscles, fried like bacon. Tasty.

Eviscerated respiratory trees "water lungs"

Tillamook second grader handling Apostichopus

Cucumaria miniata
Orange Sea Cucumber
Alaska to Mexico
Family Cucumaridae
Native

You can find this sea cucumber on a minus tide buried among the rocks along the end of the riprap breakwater at the Netarts Bay boat launch. Look for its showy bright orange tentacles (the specific name "miniata" is from Latin colored with cinnabar or vermillion) protruding from crevices between the boulders. It has ten profusely branched tentacles of equal size. The rest of its body is red to brown, giving it another common name, the Red Sea Cucumber. Its tentacles trap drifting detritus which is fed into the mouth. The tentacles retract when the animal is disturbed. It has five rows of tube feet for anchoring itself to the rocky substrate. It can grow to over eight inches long.

Photo by John DeMartini

Tentacles retracted

Tentacles exposed

Cucumaria pseudocurata
Tar Spot Sea Cucumber
British Columbia to California
Family Cucumaridae
Native

These tiny sea cucumbers are easy to find nestled in beds of California Mussels Mytilus californianus. No more than an inch-and-a-half long, they are tucked in among the byssal threads, often attached to the mussel’s shell with their tube feet, sometimes resembling dark tar spots. Their ventral side is brownish to creamy white. They have ten tentacles, eight long and two short. There are a couple of similar sea cucumbers, so the most definitive way to tell them apart is by their ossicles, the discontiguous skeletal elements just under the epidermis. The ossicles of C. pseudocurata are pictured here and confirm its identity.

C. pseudocurata can occasionally form dense aggregations on subtidal rocky surfaces away from muscle beds. They are suspension feeders, trapping phytoplankton with their tentacles. They spawn in winter, and the females brood their young.

ossicles

Paracaudina chiliensis
Rattail Sea Cucumber
Alaska to South America (All around the Pacific rim)
Family Caudinidae
Native

This greyish pink, fusiform sea cucumber resembles a fat sausage, lacks tube feet, lives buried in sand, and has a long tail-like projection from its posterior end. Its anterior end has fifteen tentacles surrounding the mouth. It ranges from intertidal to deep subtidal and is found occasionally in Netarts Bay. In its burrow, its body is relaxed and extended but contracts when disturbed. It feeds by using its tentacles to shovel sediment into its mouth and any nutrition in the sediment is digested. It then expels the remaining sediment through its posterior tail which is extended to the surface.

The rattail sea cucumber belongs to one of two orders of Holothurians, Dendrochirotida and Molpadiida, (Paracaudina is in the Molpadiida) that have nucleated hemocytes (blood cells) containing hemoglobin which has a high affinity for oxygen. This sea cucumber often lives in an oxygen depleted environment, black mud that contains hydrogen sulfide. To breath, the posterior tail, which extends above the sediment, takes in oxygenated water through the anus and delivers it to the respiratory trees, internal organs in sea cucumbers used for gas exchange.

The red colored picture is of a cleared and stained juvenile P. chiliensis prepared, photographed and labeled by Dr. John DeMartini at Humboldt State University. The following is his description with a couple of my additions (6 and 7).

The oral end is to the left. Short bifurcated oral tentacles (1) deliver sand to the mouth. The digestive system extends from the mouth as a dark pink band expanding into a stomach (2) containing dark sand grains. The intestine (3) is difficult to follow. It can be discerned as being overlapped by the stomach and extending anteriorly where some of its contents appear as brown blurry area. From here, the intestine extends downward and loses discernment, but can be seen again as a slightly brownish region below the back of the stomach. Gaseous exchange is facilitated by respiratory trees (4) appearing as narrow pink bands extending toward the oral end. The respiratory trees are plumbed into the intestine at an expanded region, the rectum (5) serving to pump water into the respiratory trees effecting gaseous exchange. Longitudinal muscles (one of which is 6) extend the length of the body. The anus (7) is at the end of the “tail.”