Tag Archive: MOLLUSKS

Phylum: Mollusca
Class: Gastropoda,
Order: Nudibranchia (sea slugs)
Family Tethydidae

Genus/ species: Melibe leonina

YouTube VIDEO  http://youtu.be/Xe2bM2kKm-U

GENERAL CHARACTERISTICS: Color a translucent gray, greenish-gray, or yellowish-gray, with opaque brown hepatic diverticula. Melibe leonina has 4-6 pairs of large, leaflike or paddlelike cerata in two rows down its dorsum and a large oral hood with two rows of filiform tentacles around its margin.

Length up to 102 mm long (4 in), 25 mm (1 in) wide, and 51 mm (2 in) across the expanded oral hood.

DISTRIBUTION/HABITAT: West coast of North America from Alaska to Baja California in eelgrass beds, kelp (especially Macrocystis) beds, harbors. When swimming it is usually upside-down, and undulates back and forth.

DIET:  M. leonina feeds on Copepods, amphipods, and ostracods, as well as small post-larval mollusks. They firmly attache itself to a kelp blade and then sweeps its raised hood downward or to the side. When food lands on the lower surface of the hood, the melibe sweeps together the two sides of the hood, and its fringing tentacles lock in the prey. The hood contracts to force the captured food into the M. leonine’s mouth.

REPRODUCTION and DEVELOPMENT:  M. leonine are hermaphrodites (they have both male and female sexual organs), and fertilization is internal. The animal can lay as many as 30,000 eggs, which are enclosed in a long, gelatinous ribbon.

REMARKS:  Noxious secretions of the melibe smell like watermelon, according to aquarists. They are gregarious animals and probably use it to keep together as well as for defense.  Most predators avoid the noxious secretions of nudibranchs; but the kelp crab is an exception. 

This species has been used for neurological research.



California Academy of Sciences, Steinhart Aquarium, Water is Life 2019

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

Ron’s flickr www.flickr.com/photos/cas_docents/sets/72157608597736188/

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

EOL eol.org/pages/454874/details


Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Subclass: Pteriomorphia
Order: Pectinoida
Family: Pectinidae

Genus/species: Crassedoma giganteum

GENERAL CHARACTERISTICS: Giant Rock Scallops have coarsely ribbed shells called valves. The upper valve is usually scallop-shaped but the lower valve takes the shape of the substrate to which it’s attached. Between the valves, the margin of the orange mantle can be seen, with a row of tiny blue eyes and a sparse fringe of short tentacles

SIZE: up to a diameter of 15 centimetres (5.9 in) in the intertidal zone and 25 centimetres (9.8 in) in the subtidal zone.

DISTRIBUTION: Pacific coast California and Canada and south to Baja California and Mexico usually inside crevices and under boulders, or cemented to rock surfaces, Depth down to about 80 metres (260 ft).

DIET IN THE WILD: C. gigantea is a suspension feeder, filtering phytoplankton from water as it passes over the gills. The particles are moved by cilia along grooves to the mouth where edible matter is separated from sediment particles. The waste is incorporated into mucous balls which are removed from the mantle cavity periodically by a clapping of the valves.

REPRODUCTION: The sexes are separate in C. gigantea. The veliger larvae that develop from the eggs form part of the zooplankton for about 40 days before settling, undergoing metamorphosis and beginning to form a shell. Juveniles are free-living, are able to swim and can attach themselves temporarily to the substrate by byssus threads. 

PREDATORS: Sunflower starfish (Pycnopodia helianthoides) and purple sea star (Pisaster ochraceus).

REMARKS: The scallops eyes can’t see images as we can, but they allow the scallop to adjust to the brightness of light. This can be of benefit when it opens its protective shells to pump water over their gills filtering food thus exposing its soft body parts to predators. As a predator approaches at least some light will be blocked and the scallop closes it shells.


California Academy of Sciences Steinhart Aquarium Dr Charles Delbeek 2018

Ron’s flickr  https://www.flickr.com/photos/cas_docents/39884701811/in/album-72157675344287795/

iNaturalist  www.inaturalist.org/taxa/54526-Crassadoma-gigantea

Global species: www.globalspecies.org/ntaxa/913354

Reef.org www.reef.org/resources/galleries/invertebrate?page=1

Eyes. www.chuckkopczakphotography.com/blog/2015/11/13/the-eyes-…

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Clade: Vetigastropoda
Superfamily: Trochoidea
Family: Turbinidae

Genus/specie: Megastraea undosa

GENERAL CHARACTERISTICS: The Wavy Turbin Snail has a heavy, sculptured shell with undulating ridges in a turbinate-conical shape with a thick, pearly lining.
The light brown or tan shell color is caused by the fibrous periostracum covered with coralline algae and other epiphytes.

Size: up to 6 inches

DISTRIBUTION/HABITAT: Found from Point Conception and the coastal Channel Islands to northern Baja California, Mexico. They range from the intertidal zone down to depths of over 250 feet.

DIET IN THE WILD: M. undosa are herbivores feeding on various types of algae.

REPRODUCTION; Year around with peaks in spring and fall.

CONSERVATION: Because wavy turban snails are hand-picked by divers, the fishery is at low risk for bycatch .
Wavy turban snails are abundantly available and have a high productivity rate, so over- harvesting is less likely.

REMARKS: The shells of wavy turban snails are used to make buttons!

The meat has an abalone-like texture and taste; foot of the snail is processed and sold to restaurants as an abalone-like product, “wav alone”.  They can be prepared many ways: grilled, sautéed, battered and fried, in pastas, in chowders and soups, and in stir fries.


California Academy of Sciences Steinhart Aquarium Tidepool 2017

Ron’s flickr https://www.flickr.com/photos/cas_docents/34539982943/in/dateposted-public/

Spearboard.com www.spearboard.com/showthread.php?t=99314

U of CA San Diego caseagrant.ucsd.edu/sites/default/files/fact-sheet-wavy-t…

Gastropods.com www.gastropods.com/2/Shell_292.shtml

Ron’s WordPress Shortlink  http://wp.me/p1DZ4b-1Qf

Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda (octopuses, squid, cuttlefish; and Nautiloidea)
Order: Octopoda
Family: Octopodidae (octopus species)

Genus/species: Octopus cyanea

GENERAL CHARACTERISTICS:  Dark eye-spots are only sometimes visible and depends upon the patterns being displayed by individual octopuses. Cryptic Coloration: they are able to change coloration, and texture of their skin, to resemble their environment (adaptive or active

Bodies up to at least 16 cm (6 inches) and arms to at least 80 cm (30 inches).

DISTRIBUTION/HABITAT: Tropical reefs from Hawaii to East Africa. O. cyanea is found in excavated lairs in coral reefs and rubble which can be located by identifying remains of clams, crabs at the entrance.


DIET IN THE WILD: Feeds during daylight hours requiring exceptional camouflage. Consumes crabs, clams and fishes.

REPRODUCTION: Males have a long modified third right arm that they hold in an upright coiled position and wave toward the female. When the female is receptive to the signaling male, he inserts his arm into the female’s oviducts to pass her spermatophores keeping his distance to avoid being eaten by the female.

Day Octopus (aka Big Blue Octopus)
Day Octopus19111242362_db83003f76_k


PREDATORS: Seals and large fish.

CONSERVATION: IUCN Red List; not assessed 2015


California Academy of Sciences Color of Life Exhibit 2015

Ron’s flickr  https://www.flickr.com/photos/cas_docents/19111242362/in/album-72157652559028013/

Encyclopedia of Life  www.eol.org/pages/593207/details

Marinebio  marinebio.org/species.asp?id=553

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

Phylum: Mollusca
Class: Polyplacophora
Order: Neolocrcata
Family: Acanthochitonidae

Genus/species: Cryptochiton stelleri

GENERAL CHARACTERISTICS: The gumboot is a long, meatloaf-like chiton with a brick-red mantle covering the eight plates of their jointed shell. The shell plates are completely internal in adults. This is the largest chiton in the world; it grows to 33 cm (13 in). It may live up to 20 years.

Gumboot Chiton32905300616_5519787bf4_k

DISTRIBUTION/HABITAT: Found from Alaska west to Japan and south to the Channel Islands, the gumboot chiton inhabits rocky intertidal areas to 80 feet, often among kelp.

DIET IN THE WILD: A nocturnal grazer, it used its long, tongue like radula to scrape off the upper tissue of soft red algae and various coralline algae, giant kelp and oarweed, in the process getting nutrition from the tiny organisms that live on the algae’s surface. The radula is covered with tiny, very hard teeth that give it the texture of rough sandpaper.


PREDATORS: Its only known predator is the large rock snail Ocenebra lurida, which drills through the chiton’s outer covering with its radula to feed on the flesh below.

REPRODUCTION: The sexes are separate; eggs and sperm are broadcast into the sea.


REMARKS: California coastal Native Americans may have eaten them, as shell plates have been found in middens. An Academy researcher states that this chiton was a food of the last resort, “tastes ghastly!”

The radulae of chitons and limpets are unique in having a high percentage of iron magnetite incorporated into the feeding teeth. Magnetite is so named because it is strongly attracted to magnets, and you can actually pick up this chiton’s teeth and radula with a magnet!
When exposed to air during low tide, the gumboot chiton can breathe at a reduced rate by absorbing oxygen from the atmosphere.

The red fuzzy stuff often on the surface is red algae. About 20 species of red algae are known to live on subtidal individuals. This chiton’s diet of red algae also contributes to its color.

Chitons are among the most ancient living mollusk groups, dating back to 400–500 million years ago.


California Academy of Sciences Steinhart Aquarium Tidepool 2017

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

ADW animaldiversity.org/accounts/Cryptochiton_stelleri/

EOL eol.org/pages/403806/details

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

Ron’s flickr https://www.flickr.com/photos/cas_docents/32905300616/in/album-72157660640336765/



Phylum: Molluska,
Class: Gastropoda
Family: ‪Aeolidioidea‬ (superfamily of sea slugs, the aeolid nudibranchs)

Genus /species: Aeolidia papillose

GENERAL CHARACTERISTICS: Its color appears to be quite variable, depending upon locale and food resources. This large aeolid grows to about 10 cm(4 in) in length and its body is covered with close obliquely arranged rows of flattened cerata.

Aeolidia papillose 6873953510_5aecc605bd_k

DISTRIBUTION/HABITAT: Common on the Atlantic coast of Europe and North America and the Pacific coast of North America. Also from  both west and east coasts of South America  Found on rocks, or may be on floats or docks often near its preferred prey. Intertidal to 380 m (116 ft) deep.

DIET IN THE WILD: Feeds almost exclusively on sea anemones.

MORTALITY/LONGEVITY: This species is famous for obtaining undischarged cnidae (cells which bear nematocysts) from its Cnidarian prey and moving to the tips of the cerata , where they are likely used for defense. If disturbed they sometimes wave their cerata. If one of the cerata is broken off, muscles within it contract, expelling the nematocysts, which then discharge . The chemical composition of A. papillosa mucus changes and does not trigger a discharge of nematocysts in the sea anemone.

REPRODUCTION/: Nudibranchs are hermaphroditic, and thus have a set of reproductive organs for both sexes, but they cannot fertilize themselves.

REMARKS: Their eyes are simple and able to discern little more than light and dark. The eyes are set into the body, are about a quarter of a millimeter in diameter, and consist of a lens and five photoreceptors.



Ron’s flickr https://www.flickr.com/photos/cas_docents/6873953510/in/album-72157660640336765/

Encyclopedia of Life eol.org/pages/402852/details

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



Phylum: Mollusca
Class: Bivalvia
Order: Filibranchia
Family: Mytilidae

Genus/species: Mytilus californianus

GENERAL CHARACTERISTICS: California mussels are relatively large mussels, with a blue-black shell with strong radial ribs and irregular growth lines. Maximum size is about 13 cm (5 in). The shell surface is often worn and eroded.


DISTRIBUTION/HABITAT:  California mussels form extensive beds, commonly mixed with gooseneck barnacles (Pollicipes polymerus). Attached firmly to the substrate by tough proteinaceous byssal threads, mussels are able to thrive in the most surf-swept areas. Mussel beds break the force of waves and collect organic debris, and so provide shelter and food for other organisms. Worms, chitons, snails, clams, isopods, crabs, and sea cucumbers are among the invertebrates found in mussel beds.

The upper limit of the mussel beds is set primarily by physical factors, particularly time out of water. The lower limit is set in part by the predation of the ochre star (Pisaster ochraceus), which practices vertical foraging, moving up and down with the tides. Mussels range from low intertidal to 40 m (131 ft) deep and are common in surf-swept, rocky areas, and are found from Alaska to southern Baja California.


DIET IN THE WILD: Mussels filter fine organic detritus and living plankton from sea water. A mussel filters 1.8 l to 2.8 l (2 to 3 qts) of water an hour.


PREDATORS: California mussels are favored food items of seas stars (especially ochre stars), crabs, predatory snails, shorebirds, sea otters, and humans. Sea otters have devastated formerly extensive mussel beds in Monterey Bay.


REPRODUCTION: Mussels are either male or female. During breeding they broadcast sperm or eggs into the sea where fertilization occurs. They spawn November to May. Mussel larvae are free-swimming for about four weeks. After settling and attachment they grow to full size in about three years.



  • The California mussel attaches to rocks by fibers called byssal threads. These threads are produced as a liquid by the byssal gland. The liquid runs down a groove formed by the foot. When the foot pulls back, exposing the liquid to sea water, the liquid solidifies into a thread.
  • A large mussel moves by breaking old threads, then attaching new ones to another spot; a small mussel creeps around on its foot.
  • By filtering algae spores from the water, mussels may limit algae growing around mussel beds.
  • Coastal areas are at risk from development and pollution. Mussels are also at risk because many of their homes are in danger of being ‘loved too much’ by too many tide pool visitors.


California Academy of Sciences Docent Guide 2015

flickr http://www.flickr.com/photos/cas_docents/5118861762/in/set-72157608597736188/

WordPress shortlink:  http://wp.me/p1DZ4b-wF

Encyclopedia of Life eol.org/pages/449960/details

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

Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Sepiida
Family: Sepiidae (Cuttlefishes, shell internalized)

Genus/species: Sepia bandensis

GENERAL CHARACTERISTICS:. Sepia bandensis has 8 arms with rows of suckers along each and 2 feeding tentacles. It moves by the undulation of lateral fins that surround the body. Cuttles have an internal shell within their bodies that they can fill with more or less gas to create neutral buoyancy. The cuttlebone is often collected and used as a calcium supplement, beak sharpener, and all-purpose toy for caged birds.
Like most cephalopods, cuttlefish have 3 hearts. Two hearts pump blood to the gills, and a central heart pumps oxygenated blood to the body.
Length: 5 cm – 10 cm (2 in – 4 in)


DISTRIBUTION/HABITAT: The Indo-Pacific region, including the Philippines, Indonesia, and Papua New Guinea.
Found in shallow coastal waters near or on coral reefs or sandy substrates.


DIET IN THE WILD: Crustaceans and fish. The Cuttlefish changes colors and patterns as it approaches prey then ejects its feeding tentacles to capture its prey with its suckers and eating it with a parrot-like beak and a radula. Active diurnally.

ACADEMY DIET: Shrimp and crab (M Avila, staff biologist)


LONGEVITY: Life span: 6 mos. to 3 yrs.

eggs below


REMARKS: Masters of camouflage, cuttlefish and most cephalopods can change their colors, shapes and textures in seconds to avoid predators and blend into their surroundings. They have keen vision, but are color blind.

They also produce large amounts of ink, both as a decoy and foul-tasting deterrent. Known as sepia ink, after the genus name of cuttlefish, it was a dye once prized by artists.

The Steinhart Aquarium is the first institution in the U.S. to breed dwarf cuttlefish. To date, (2010) more than 350 have hatched at the Academy, most of which have been sent to other aquaria and research institutions. Quote from Rich Ross, Academy biologist and cuttlefish breeder extraordinaire: Over time, [cuttlefish] learn to recognize and respond to you, and will often greet you when you walk into the room (or maybe they just know you bring the food). 

Color of Life note: Cuttlefish are excellent examples of cryptic coloration. Chromatophores in the cuttlefish skin are controlledneurologically, allowing almost immediate color change disappearing into its background right before your eyes.
Ref: California Academy Color of Life exhibit


California Academy Color of Life exhibit

The Marine Biology Coloring Book 2nd Ed. Thomas Niesen 2000

EOL Encyclopedia of Life  eol.org/pages/591499/details

Ron’s flickr  https://www.flickr.com/photos/cas_docents/3953684359/in/album-72157652559028013/

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

Phylum: Mollusca
Class: Gastropoda (slugs, snails, nudibranchs, abalone)
Order: Archaeogastropoda (sea snails)
Family: Haliotidae (abalones)

Genus/species: Haliotis rufescens

GENERAL CHARACTERISTICS: The red abalone is a large limpet-like snail with a flattened and rounded shell. The shell can reach up to 30 cm (11.8 in) in length and is usually brick-red and overgrown with fouling organisms. Color varies with diet and varies between aquamarine, green, or white. Water enters anteriorly through row of holes parallel to the rim of the shell and exits posteriorly carrying waste products and gametes. When in danger, the abalone clamps its shell tightly to the substrate, protecting soft parts of its body. The shell’s color is influenced by the animal’s diet. The red color is from the pigment phycoerythrin consumed in its red alga diet. Color varies with a diet of brown algae (varies between aquamarine, green, or white).

DISTRIBUTION/HABITAT: Red abalone are found from Oregon to Baja California. They are uncommon in the lower intertidal zone in rocky areas with heavy surf. Most are now found at six to 17 m (20 to 56 ft) depth in central California.


DIET IN THE WILD: Small abalones feed on diatoms and algae; larger animals browse the seaweeds. Red abalone eat algae, especially red and brown species. Usually foraging at night, they trap drifting pieces of algae (kelp) with the tentacles that extend from the foot. The algae is then carried by the foot to the mouth, and is torn and consumed with by the radula.

flickr Feeding Video http://www.flickr.com/photos/cas_docents/6393536637/in/set-72157626486149324


PREDATORS: Sea stars, crabs, octopuses, sea otters and human divers are among the abalone’s primary predators.

REPRODUCTION: After spawning takes place, fertilized eggs sink. Larvae develop in the plankton until they settle to the bottom, metamorphose, and begin to graze. Growth slows with increasing size and age. Mortality is very high in the planktonic stages. Mature individuals can live more than 20 years.

REMARKS: Red abalone are highly endangered due to overexploitation by the abalone fishery. The population plummeted in the late twentieth century, but poaching continues to be a problem. California passed many strict regulations to protect the red abalone: abalone smaller than 20 cm (8 in) in diameter are protected, the canning of abalone is prohibited, and the shipment of fresh or frozen meat out of California is prohibited. Red abalone is the only species that can still be fished. Aquacultured abalone is now increasingly available.

Abalone blood is blue-green and cannot clot making injury possibly fatal.

Red Abalone Shell19600303421_7eae835178_z

Color of Life note: Iridescence is caused by two or more semi-transparent, inorganic and/or organic surfaces that cause multiple light reflections. An example found in our tidepool is the Red Abalone inner shell surface which produces an impressive vibrant luster when exposed to light.  The aragonite and conchiolin secreted by the abalone in forms a crystalline structure that reflects light, causing the shell’s iridescence. The inner surface of the shell is known as mother-of-pearl, or nacre. Ref: California Academy of Sciences, Color of Life Exhibit 2015   Jewelry is still made from abalone shells and is quite popular.                        Ref: www.best-deal.com/search/landing/query/red+abalone+shells...


Other references

Marine Biology Coloring book, T.M. Nielsen, 2nd Ed. Harper Resource 1982, 2000.

Encyclopedia of Life  eol.org/pages/620396/details

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

California Fish and Game www.dfg.ca.gov/marine/pdfs/response/abalone.pdf

Ron’s flickr https://www.flickr.com/photos/cas_docents/6393536637/in/album-72157608597736188/


Kingdom: Animalia
Phylum: Mollusca:
Class: Gastropoda  (snails and slugs)
Order: Vetigastropoda:  (primitive group of sea snails)
Family: Trochidae (“top snails”, because in many species the shell is shaped like a toy top)

Genus/species: Norrisia norrisi

Red Foot Moon Snail Norrisia norrisi IMG_7601

GENERAL CHARACTERISTICS: Smooth brown shell that ranges in size from a few mm to 55mm or 2 inches.

DISTRIBUTION/HABITAT: Eastern Pacific found on kelp from Point Conception to Baja California, May live in water 15-24°C or 59 to 75°F.

DIET IN THE WILD: The Norris’ top snail feeds mainly on brown algae but in aquariums they use their file-like tongue or radula to eat most types of algae helping to keep the aquarium clean.

PREADATORS: Commonly eaten by seastars.

REMARKS: Used to help control algae in the Philippine coral reef. PR04


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