Category: ECHINODERMS


TAXONOMY
Kingdom:  Animalia
Phylum:  Echinodermata
Class:  Asteroidea
Order:  Valvatida
Family:  Oreasteridae

Genus/species: Protoreaster nodosus

GENERAL CHARACTERISTICS:  background body color is highly variable; may be beige, brown, orange, red or other hues, such as green or blue. Horn-shaped tall dark nodules are conical and arranged in a  single row, radially on the dorsal (top) side. Most horned sea stars found are a roughly rigid five-pointed star-shape (occasionally 4 or 6) with tapering arms to the end. They are blue, dark green, dark chocolate or black, sometimes surrounded by milk chocolate-colored margins are responsible for this sea stars common name. 

Diameter up to 30 cm (12 in).

Protoreaster nodosus15010829781_2ff5562e7a_o

 DISTRIBUTION/HABITAT: Red Sea, Indian and western Pacific oceans. Found in shallow sheltered sand and seagrass beds. Depth range 1 – 582 m (3.3 – 1900 feet).

seastar3289508350_970ef3292c_o 

DIET IN THE WILD: Mouth is located ventrally (bottom). It feeds by extending its stomach out of its mouth, covering food, and digesting it externally.  P. nodosus  prefers sponges, corals, clams and snails, other invertebrates; also opportunistic carrion feeders. 

 Protoreaster nodosus3289508974_49c4d004de_b

REPRODUCTION: Broadcast spawner. As in other sea stars, fertilization is external. Eggs and sperm are stored in the rays and released simultaneously. Larvae look nothing like the adults. The form that first hatches from the eggs is bilaterally symmetrical and planktonic. Larvae eventually settle and transform into tiny sea stars.

Lifespan up to 17 years

sea star15201906310_bc5840e0c0_o 

CONSERVATION: IUCN Not Evaluated

REMARKS: The Chocolate Chip Seastars are also called “knobbly sea star” and the “horned sea star.”
Like all sea stars, the chocolate chip sea star can regenerate lost limbs, as long as the central disk of the body is intact. Some species can regenerate an entire body from an arm or arm segment.

References

California Academy of Sciences Steinhart Aquarium Color on the Reef 2017   AQA13

Ron’s flickr  https://www.flickr.com/photos/cas_docents/15010829781/in/set-72157608501343477/

Woods Hole www.whoi.edu/science/B/people/kamaral/SeaStar.html

Bishop Museum hbs.bishopmuseum.org/pubs-online/pdf/op11-8.pdf

Georgia Aquarium http://www.georgiaaquarium.org/animal-guide/georgia-aquarium/home/galleries/aquanaut-adventure/gallery-animals/chocolate-chip-sea-star

Reef Creature Identification, Humann and Deloach 2010, page 426

Encyclopedia of Life  eol.org/pages/4704956/details

Marine Biology http://link.springer.com/article/10.1007%2Fs00227-008-1064-2

Ron’s WordPress shortlink http://wp.me/p1DZ4b-1ml

TAXONOMY
Kingdom: Animalia
Phylum: Echinodermata
Class: Asteroidea
Order: Forcipulatida
Family: Asteriidae

Genus/species: Pisaster ochraceus

GENERAL CHARACTERISTICS: Color varies from orange, violet, dark brown or mottled, but very rarely ochre. One study showed that less than two percent of the individuals in three local Northern California populations were “ochre” in color. When dead and dry they become ochre in color.


The aboral surface contains many small spines (ossicles) that are arranged in a netlike or pentagonal pattern. Papulae or coelomic pouches give the seastar’s surface a soft, fuzzy appearance. They are used for respiration and waste excretion. P. ochraceus may have an arm radius of up to 28 cm (11 in), but the more common radius is half that figure. They typically have five arms or rays, but the number can range from four to seven. Like all sea stars, an adult P. ochraceus has tube feet which they use for locomotion and for handling prey.

DISTRIBUTION/HABITAT: Ochre stars range from Alaska to Santa Barbara County, California. They prefer the low-to-mid intertidal zones on rocky shores, especially on mussel beds, and are also found in the subtidal zone to a depth of 88 m (288 ft). Juveniles are found in crevices and under rocks.

DIET IN THE WILD: California mussels are the favored and locally abundant prey. They also consume acorn barnacles, emarginated dogwinkles, gooseneck barnacles, owl limpets, etc. They can insert their stomach into slits as narrow as 0.1 mm between the valves of bivalves and begin digestion.

ACADEMY DIET: Manila clams, chopped fish, large krill, chopped squid; it also eats other exhibit inhabitants.

REPRODUCTION: They are mainly dioecious (separate sexes). Male gametes are produced, but at a later date only females gametes are produced. During a transitional period, both eggs and sperm are produced. The gonopores of the individual gonads open at the bases of the arms. Fertilization is external. Larvae are free-swimming and plankton-feeding.

LIFESPAN: Up to 20 years

PREDATORS: Adults are eaten by sea otters and seagulls. According to Dr. Thomas Niesen, the sea otter can crunch them up but is also known to bite off the tips of the arms and suck out the gonads.

REMARKS:  One study showed that less than 2% of the individuals in three local Northern California populations were “ochre” in color. When dead and dry they become ochre in color.

P. ochraceus tolerate strong surges, large temperature changes, dilution by rainfall. It is resistant to desiccation and it can tolerate a loss of thirty-percent of its body weight in body fluids.

Sea stars can regenerate lost arms with a portion of the central disc intact and in some species from a single arm.

NOTE:   SEA STAR WASTING SYNDROME has become a major issue in both the Pacific and Atlantic Oceans since 2013. For an excellent summary check this link to the University of Santa Cruz 9-9-14.  http://www.eeb.ucsc.edu/pacificrockyintertidal/data-products/sea-star-wasting/updates.htm

Fitzgerald Marine Reserve. www.fitzgeraldreserve.org/newffmrsite/wp-content/uploads/...

11-17-14 Recent research identifies a virus (Parvoviridae) to be responsible for the wasting disease. Introduced virus was able to infect healthy sea stars with the virus, which then leads to the wasting symptoms. Published in the Proceedings of the National Academy of Science. http://theconversation.com/mystery-virus-that-turned-millions-of-starfish-into-goo-is-finally-identified-34336

 

Additional References

California Academy of Sciences Docent Tidepool Guide 2015

Woods Hole www.whoi.edu/science/B/people/kamaral/SeaStar.html

Bishop Museum hbs.bishopmuseum.org/pubs-online/pdf/op11-8.pdf

Encyclopedia of Life  eol.org/pages/598469/details

Animal Diversity Web, U of Michigan  animaldiversity.ummz.umich.edu/accounts/Pisaster_ochraceus/

Ron’s WordPress Shortlink  http://wp.me/p1DZ4b-sC

Ron’s flickr  https://www.flickr.com/photos/cas_docents/3407968572/in/set-72157608501343477/

 


TAXONOMY
Phylum: Echinodermata
Class: Echinoidea
Order: Echinoida
Family: Strongylocentrotidae

Genus/species: Strongylocentrotus purpuratus

GENERAL CHARACTERISTIC: Round body with radially symmetrical test, (shell), covered with large spines 0.5 cm (2 in) in diameter, rarely to 10 cm (4 in). Test and spines are pale green (young) to purple (adults). Also covering the test or shell, are tube feet and pedicellariae (pincers). The long
suckered tube feet visible above the spines are used for locomotion and capture of food, which is then passed along to the mouth. The oral side of the urchin, on which the mouth is located, faces the substrate (down). Sexes are not physically distinguishable from one another (monomorphic).

DISTRIBUTION/HABITAT: British Columbia to Baja California in the lower intertidal to 160 m (525 ft) depth. Rounded burrows in rock that have been scoured out by the present or previous urchin using its teeth (Aristotle’s lantern) and spines, a strategy that protects from predators and surge.  Subtidal purple urchins live, often in large numbers, on the substrate among kelp holdfasts.

 

DIET IN THE WILD: Herbivore/Detritivore. Uses calcite (CaCO3) teeth (Aristotle’s lantern) to feed on kelp, other algae, diatoms and scavenge on dead animals. These urchins prefer the giant brown kelp Macrocystis and can destroy entire forests of kelp which are commercially important for fisheries. Algin a product from kelp is also used in the manufacturing of plastics, paints and as a thickening agent in foods such as gravy and pudding.


REPRODUCTION: Sexually mature during their second year. Sexes are separate, although hermaphrodites occur. Broadcast spawning deposits sperm or eggs into the sea where random fertilization occurs. Pluteus larvae hatch, drift and settle. Growth after metamorphosis is slow.

PREDATORS: Preyed upon by seastars such as the sunflower star and cancer crab species as well as fish such as the California sheepshead, shorebirds and sea otters. Sheephead blow over sea urchins and nibble at the oral side where the spines are shortest. When approached by most sea stars, the urchin allows the potential predator to get close, then uses its pincers to attack the sea star’s tube feet. Most sea star species will beat a hasty retreat; however, the sunflower star is too big and fast; the urchin cannot escape and is swallowed whole! Average lifespan 20 years but can live to more than 30 years.

CONSERVATION: CITES; no special status

REMARKS: Purple pigments from this urchin lodge in the bones and teeth of sea otters, turning the otter’s skeleton and teeth purple.

In the wild, they protect themselves from predation, drying out, and damage from the sun’s UV light by covering themselves with seaweed or shells.

Sea urchin is commonly used in sushi and is considered a delicacy Japan. The primary urchin harvesting company in California sends 75% of the harvest to Japan.

LOCATION

RockyReefcluster, Abalone and urchins, Rocky Coast Main Exhibit, Tidepool

References

California Academy of Sciences Docent Water is Life Guide 2015

eol  http://eol.org/pages/598175/details

Ron’s flickr http://www.flickr.com/photos/cas_docents/sets/72157608501343477/

Ron’s WordPress shortlink: http://wp.me/p1DZ4b-vq

TAXONOMY

Kingdom: Animalia
Phylum: Echinodermata
Class: Asteroidea (Starfish or sea stars)
Order: Forcipulatida
Family: Asteriidae

Genus/species: Asterina miniata

GENERAL CHARACTERISTICS: Colors may be colored red, orange, brown, purple or mottled. They have webbing between their short, triangular arms, which gives them a batlike look. Size is up to 20 cm (eight inches) across. Radially symmetrical they normally have five arms, but they occasionally have as many as nine arms. They have tube-feet that allow locomotion.

DISTRIBUTION/HABITAT: Sitka, Alaska to Baja California, Mexico. Found in low intertidal areas on rocks overgrown with surfgrass, large algae and sponges. Depth intertidal to 290 m (950 ft) on rocky or sandy substrates.

DIET IN THE WILD: Sensors at the end of each arm that sense light and detect prey. Typically an omnivore or scavenger: surfgrass, algae, colonial tunicates, organic films on hard surfaces, as well as other seastars.  Like most seastars, feeds by everting its stomach over prey.

See everted Bat Star stomach below.

REPRODUCTION: Usually spawns May to June. The male broadcasts sperm and the female broadcasts eggs from pores near the bases of their arms. Embryos and larvae are transparent.

PREDATORS Other sea stars, molluscs, and crustaceans. Like some other sea stars, bat stars can sometimes avoid predation by secreting chemicals that evoke flight responses in other animals.

CONSERVATION: IUCN No special status. Collecting by tidepool visitors has diminished some populations, for example around the Monterey Peninsula.

REMARKS: When two bat stars bump into each other, a gentle brawl begins. They seem to be “arm wrestling” in a slow motion skirmish where no winner is usually obvious.

Bat stars lack the pedicillariae, or pincers, common to most other sea stars and used to clear the animal of unwanted parasites and other debris. Even so, bat stars are free of debris, perhaps because small, constantly moving hairs (cilia) discourage settling

Sea stars have endoskeletons made up of plates (calcified ossicles) joined by connective tissue to protect the bat star’s vital organs.  The bat star’s ossicles are so large and defined that they look like rough shingles. 

 

REMARKS:  SEA STAR WASTING SYNDROME has become a major issue in both the Pacific and Atlantic Oceans. For an excellent summary check this link to the University of Santa Cruz 9-9-14.  http://www.eeb.ucsc.edu/pacificrockyintertidal/data-products/sea-star-wasting/updates.htm

Fitzgerald Marine Reserve.  http://www.fitzgeraldreserve.org/newffmrsite/wp-content/uploads/2014/09/BetweenTides_9-14_web.pdf

 

References

Monterey Bay Aquarium  http://www.montereybayaquarium.org/animal-guide/invertebrates/bat-star

U. of Michigan Animal Diversity Web http://animaldiversity.ummz.umich.edu/accounts/Patiria_miniata/

Ron’s flickr    http://www.flickr.com/photos/cas_docents/sets/72157608501343477/

Ron’s WordPress shortlink   http://wp.me/p1DZ4b-to

TAXONOMY
Kingdom: Animalia
Phylum: Echinodermata
Class Asteroidea
Order: Forcipulatida
Family: Asteriidae

Genus/species: Pisaster giganteus

 GENERAL CHARACTERISTICS: Giant sea stars have five arms covered with white, pink, or purple spines surrounded by blue tissue at the base, and range in color from red, orange, brown, or even green. The surface has brown fuzz and pedicellariae. They have a maximum arm span of about 60 cm (23.6 in). P. giganteus would seem improperly named, as the average intertidal specimen is smaller than the average P. ochraceous; however subtidal specimens grow considerably larger.

7137830837_192c64b940_k 

DISTRIBUTION/HABITAT: They are distributed along the eastern Pacific coast from British Columbia to Baja California. They are common on rocky substrates, but also found on sand from the middle to lower intertidal zone down to 90 m (300 ft).

Giant Sea StarIMG_1040.JPG - Version 2

DIET IN THE WILD: Their typical prey are hard-shelled organisms such as mussels, snails, and barnacles by extending its stomach to fit into tiny gaps in bivalves such as mussels. However, they may occasionally eat anything slow-moving enough to be caught, such as a dying fish or shellfish, anemones, or other sea stars.

Giant Seastar IMG_8851

PREDATORS: Sea gulls and sea otters are sea star predators.

REPRODUCTION: Individual sea stars are male or female. Both sexes release gametes into the water for external fertilization. Larvae are planktonic and have bilateral symmetry. Giant sea stars live about 20 years.

REMARKS:  SEA STAR WASTING SYNDROME has become a major issue in both the Pacific and Atlantic Oceans. For an excellent summary check this link to the University of Santa Cruz 9-9-14.  http://www.eeb.ucsc.edu/pacificrockyintertidal/data-products/sea-star-wasting/updates.htm

Fitzgerald Marine Reserve.  http://www.fitzgeraldreserve.org/newffmrsite/wp-content/uploads/2014/09/BetweenTides_9-14_web.pdf

Tidepool 

References

California Academy of Sciences Tidepool Exhibit 2015

Woods Hole www.whoi.edu/science/B/people/kamaral/SeaStar.html

Bishop Museum hbs.bishopmuseum.org/pubs-online/pdf/op11-8.pdf

Encyclopedia of Life  eol.org/pages/598468/details

Animal Diversity Web, ADW  http://animaldiversity.ummz.umich.edu/accounts/Pisaster_giganteus/classification/

Ron’s flickr  https://www.flickr.com/photos/cas_docents/7137830837/in/set-72157608501343477

Ron’s WordPress shortlink  http://wp.me/p1DZ4b-1mV

TAXONOMY
Kingdom: Animalia
Phylum: Echinodermata
Class Asteroidea
Order: Forcipulatida
Family: Asteriidae

Genus/species: Pisaster brevispinus


GENERAL CHARACTERISTICS The pink sea star reaches a maximum diameter of nearly 65 cm (2 ft); however, individuals are usually smaller. Its central disc has a raised, humplike appearance. They are robust, pink in color and have aboral spines much shorter than those of other Pisaster species, thus its scientific name, which translates as “short-spined sea star.”

7137858011_f41cdc4304_k

DISTRIBUTION/HABITAT They range from Sitka, Alaska to San Diego County, California. They can occasional be seen in the low intertidal zone, but are more commonly found in deeper water to 90 m (300 ft ) on sand and mud substrates, but sometimes on rocks and pier pilings in calm waters. They cannot tolerate prolonged exposure to air.

DIET IN THE WILD: Pink sea stars prey on live clams, snails, sand dollars, barnacles, mussels, – annelid worms, and scavenge on dead fish and squid. On soft surfaces, P. brevispinus digs into sand or mud with its arms. It also can extend its tube feet (the ones around its disk) to a length of 20 cm (8 in). When the tube feet reach a clam buried in the mud, they attach and the sea star hauls it up. On shale, it can lower its stomach into the burrow of a clam and digest the animal in place. Their large size may well be due to their access to a plentiful food supply of large organisms unavailable to potential competitors.

PREDATORS Large adults have few predators, but they may be taken by the sunflower sea star Pycnopodia helianthoides. Sea otters have been known to detach rays to consume gonads, and sea gulls occasionally feed on individuals exposed during very low tides.

REPRODUCTION They spawn in the spring. Sexes are separate and fertilization takes place externally. Larvae disperse in the water column.

Pink stars can live up to 20 years.



REMARKS: Can chemosense clams through sand. May dig down to the clam for 2 –3 days or extend tube feet to the clam a distance equal to the arm radius to 20 cm (7.8 in). Once contacted,
the clam is lifted from the substrate or the stomach may be everted to 8 cm (3.15 in) to digest the prey in place. Some sand-bottom invertebrates including the sand dollar Dendraster excentricus and the snail Olivella biplicata chemosense the presence of a pink star and attempt to avoid contact by burrowing.

References

California Academy of Sciences Tidepool exhibit 2015

Walla Walla Univ. www.wallawalla.edu/academics/departments/biology/rosario/…

EOL eol.org/pages/598470/details

Ron’s WORDPRESS SHORTLINK  http://wp.me/p1DZ4b-tA

Ron’s flickr http://www.flickr.com/photos/cas_docents/sets/72157608501343477/

TAXONOMY
Kingdom: Animalia
Phylum: Echinodermata
Class: Holothuroideaia
Order: Aspidochirotida
Family: Stichopodidae

Genus/species: Parastichopus parvimensis

GENERAL CHARACTERISTICS: Colored brown above, lighter below. Conical black-tipped papillae on the dorsal side provide the common name. The mouth and anus are on opposite ends of their cylindrical bodies. Tube feet aide in gathering food as well as ambulating.Length to 25 cm (10 inches). 

DISTRIBUTION/HABITAT: Monterey Bay, California to Baja California. Found on sandy or muddy-sandy soft bottoms between rocks or in eelgrass beds. Sub tidal to 27 m (89 feet) in depth.

DIET: Digests organic detritus and small organisms in soft sediments.

REPRODUCTION?DEVELOPMENT: Have separate sexes (look-alike), and eggs are fertilized externally. Broadcast spawning usually takes place in November, and each female can produce thousands of eggs. After fertilization, a larva is formed which metamorphoses into a Sea Cucumber after a few weeks.

MORTALITY/LONGEVITY: Eaten by sea stars including the sunflower star. Sea otters and humans are also predators. Lifespan estimated to be 5-10 years in the wild.

CONSERVATION: IUCN Red list; Not Evaluated

REMARKS: Holothuroids differ from echinoderms, because they have a water vascular system full of body fluid rather than sea water.  Like other echinoderms, cucumbers have a calcareous skeleton; but in their case it is only vestigial, composed of plates and spicules of lime buried in the skin and serving merely to stiffen the body wall. Respiratory trees are the lungs of a sea cucumber. These hollow branched organs lie inside the body cavity on either side of the posterior intestine. The base of the tree connects to a muscular cavity, or cloaca. Oxygen is transferred across the thin membrane into the fluids of the body cavity. When the oxygen is depleted, the main body wall contracts to squeeze water out of the trees. 
When threatened, it can expel all its internal organs through its anus (evisceration) and grow new ones in 2-4 weeks. It can also expel sticky filaments to ensnare or confuse predators. Warty sea cucumbers and their related species are sometimes called the “earthworms of the sea,” as they cultivate the seafloor in much the same manner as earthworms cultivate the soil. Oral tube feet around the mouth are covered with a sticky mucus that traps food particles from the seafloor’s sediment and mud. In areas where overfishing has reduced the population of sea cucumbers, the seafloor hardens, thus destroying a habitat for other bottom-dwelling creatures. Can walk on tube feet if stressed up to one yard every 15 min..Humans eat a variety of sea cucumber species, including Warty sea cucumbers. The demand is greatest in Asian countries, for consumption and folk medicine applications. It is considered to be widely overfished.

 

 

 

Parastichopus parvimensisIMG_8852 - Version 2

 

References

ADW Animal Diversity Web, U. of Michigan  http://animaldiversity.ummz.umich.edu/accounts/Parastichopus_parvimensis/

Encyclopedia of Life  eol.org/pages/597920/details

Monterey Bay Aquarium  www.montereybayaquarium.org/animal-guide/invertebrates/wa…

Ron’s flickr  https://www.flickr.com/photos/cas_docents/3702926813/in/set-72157608501343477

 Ron’s WordPress Shortlink  wp.me/p1DZ4b-s6

 

TAXONOMY
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea (Sea urchins)
Subclass: Cidaroidea
Order: Cidaroida
Family: Cidaridae

Genus/species: Eucidaris tribuloides

GENERAL CHARACTERISTICS: Brown body with thick spines in all directions. 

Slate Pencil UrchinIMG_1479

DISTRIBUTION/HABITAT: North Carolina through Brazil, Caribbean, Bahamas, Florida. Found in coral reef crevices, in turtle grass beds, or under rocks and rubble in back reef lagoon areas. Depth to 800 m (usually 50 m). 

 

 

Slate Pencil UrchinIMG_1478

DIET IN THE WILD: Nocturnal omnivore: algae and small invertebrates such as sea squirts and sponges.

Slate Pencil UrchinIMG_0664

REMARKS: The spines of pencil urchins, unlike other urchin groups, are not covered with epidermis. They are, however, often covered with algae and epizoans that provide excellent camouflage. Spines are also covered with barbs that can inflict serious pain to a predator. Seek shelter in rocky crevices by day, using the thick spines to maintain a protected position.

References

Encyclopedia of life eol.org/pages/600976/details

Smithsonian Tropical Research Institute 

biogeodb.stri.si.edu/bocas_database/search/species/1130

Animal Diversity Web animaldiversity.ummz.umich.edu/accounts/Eucidaris_tribulo…

Ron’s flickr https://www.flickr.com/photos/cas_docents/4330820247/in/set-72157608501343477

Ron’s WordPress shortlink  http://wp.me/p1DZ4b-1nk

Caribbean  PR36

TAXONOMY
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Order: Diadematoida
Family: Diadematidae

Genus/species: Diadema setosum

GENERAL CHARACTERISTICS:  Usually black but some or all of them can be grey or white. Very long, black spines are up to 30 cm (1.1 inches). Orange-red ring around anal cone at the center of its dorsal surface is distinctive. Weight 35 gm (1.25 oz) to 80 gm (2.8 oz).  Adult test to 9 cm (3.5 inches) diameter with a distinct pattern of iridophores, usually with 5 white dots.  Height to around 40 mm (1.5 inches) high. 

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DISTRIBUTION/HABITAT: Red Sea, east Africa to western Pacific (Philippines) in low tide areas to 20 m (66 ft) on rubble and seagrasses. Often abundant in shallow water areas that have been recently disturbed. Also in lagoons and on coral and rocky reefs.

4333507132_3945bbf3a3_b

DIET IN THE WILD: Herbivore. Hides during the day, and emerges at night to feed on algae, plankton, and waste material. Its feeding habits help keep the reef free from coral-smothering algae; however, too many of these algal-eating machines can actually threaten a reef, scraping away living coral as they devour algae and leaving little food for other herbivores.

CONSERVATION: IUCN Red List ; not evaluated.

REMARKS: Uses hundreds of flexible, tube feet to move around, eat and breathe.

The venom is mild and causes swelling and pain, and gradually diffuses over several hours. Tiny hooked barbs often require surgical removal.

Commensal with a number of species, including various shrimps and fishes.

2985491545_3eef5bdec7_o

Sea-grass shallows PR03a

References

Encyclopedia of Life  eol.org/pages/2942801/details

Archive www.arkive.org/long-spined-sea-urchin/diadema-setosum/

WordPress Shortlink  http://wp.me/p1DZ4b-Qv

flickr http://www.flickr.com/photos/cas_docents/sets/72157608501343477/with/4333507132/

TAXONOMY
Kingdom: Animalia
Phylum: Echinodermata (“spiny-skinned” animals including sea stars, brittle stars, sea urchins, sand dollars, and sea cucumbers)
Class: Echinoidea  (sea urchins and sand dollars)
Order: Clypeasteroida
Suborder: Scutellina
Family: Dendrasteridae

Genus/species: Dendraster excentricus

GENERAL CHARACTERISTICS: Closely related to sea urchins, except for a more flattened, silver-dollar skeleton (test).
The tube feet, characteristic of echinoderms, are used for locomotion, respiration, sensing the environment, grasping and transporting food particles to the centrally located mouth on the underside of the test, and attachment to the substrate. The anus is near the edge of the test.
Very short spines which are covered with tiny hair-like cilia are closely packed together on the surface which feels like velvet.
Diameter to 8 cm (3.2 inches).

Eccentric Sand Dollar 3289660142_4458838cfd_b

DISTRIBUTION/HABITAT: Southeastern Alaska to Baja California. Found in subtidal to low intertidal zone on sandy or sandy-muddy substrates in cool water near the shore, but deep enough to avoid wave surge. Depth to 40 m (131 feet) but usually shallower.

Eccentric Sand Dollar 3427754072_18f944b159_b

DIET IN THE WILD:  They are oriented flat or more often vertical with entire bed oriented the same way to catch phytoplankton detritus, diatoms, and plankton such as crab larvae and amphipods. They are captured by mucous-covered spines and pincers (pedicillariae). Food particles are then carried to the mouth in the center of the lower body surface by cilia on spines where it is broken up by jaws of a small aristotle’s lantern. The tube feet are also used for grasping and transporting food.

REPRODUCTION: Broadcast spawner. Sperm and eggs are released from separate individuals. After fertilization, free-swimming bilateral larvae form, which eventually change to radially symmetrical individuals that settle to a sandy or muddy substrate similar to sea urchins.

Longevity: averages 10 years.

PREDATORS: Fish, sea stars, crabs, humans.

CONSERVATION: IUCN; Not evaluated.

REMARKS:  Cilia covered spines are used in wave-like motions for movement and burrowing. Tube feet away from the mouth are also used for locomotion. 
Young sand dollars ingest large sand grains that act like a diver’s weight belt to help them maintain position.
The age a sand dollar can be determined by counting the growth rings on the plates of the exoskeleton.

References

U. of Michigan (ADW) Animal Diversity Web  http://animaldiversity.ummz.umich.edu/accounts/Dendraster_excentricus/ 

Walla Walla University  http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Echinodermata/Class%20Echinoidea/Dendraster_excentricus.html 

Monterey Bay Aquarium  http://www.montereybayaquarium.org/animal-guide/invertebrates/sand-dollar

Ron’s flickr  https://www.flickr.com/photos/cas_docents/3289660142/in/set-72157608501343477

Ron’s WordPress shortlink  http://wp.me/p1DZ4b-1mA

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