I found this neat gastropod while tidepooling in the San Francisco Bay Area. The Angular Unicorn is a type of predatory snail found on the intertidal zones. Its shell exterior varies from gray to yellowish-white. Several white spiral cords, with dark interrupted grooves between, encircle the shell.

The Angular Unicorn belongs to the mollusk Family Muricidae, a large and varied group of small-to-large predatory sea snails, commonly known as Murex Snails or Rock Snails.

It is found on protected rocks and pilings in the high to mid-intertidal zone and its range is most of the California coastline. I found these in plain sight, hanging out on rocks during low tide. They eat barnacles, mussels, snails and other types of invertebrates. Often times, hermit crabs utilize their shell once the snail dies.

When this snail finds its prey, it attaches itself to its prey’s shell. Then it produces hydrochloric acid, enzymes, and other substances to soften the prey’s shell. Once soft, they rasp it away with their radula (a structure of tiny teeth), thus creating a characteristic hole.

After breaking through the shell, the Angular Unicorn sticks its mouth inside the clam, barnacle or snail and, using its radula, rasps away the clam’s tissue, basically eating it alive.

This species gets its “unicorn” common name from the little pointy projection that it has at the front of its shell.

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While walking the streets of Fukuyama, Japan, the canals along the avenues had several different types of creatures living in them – the most conspicuous being this shelled being. Their variation in the form of the shell is considerable, with colors of dark brown, yellow-green and/or dark green.

The Eastern Asiatic Freshwater Clam can grow to almost a foot in length and attain an age of 12–14 years. It can reproduce by the end of its first year, while only an inch and a half in size. The form of the shell is relatively short and elliptical to almost rounded and very high in the central part.

This species is a habitat generalist found in heavily modified and artificial habitats and is tolerant to high siltation rates. It prefers substrates of silt and clay, turbid conditions with relatively high water temperatures and is found in either standing or slow-flowing water. It is established worldwide.

Belonging to the Unionidae Family, like all members of its family, it has an obligatory parasitic stage, in which the larva must attach on a host fish to complete its development. Host species include invasive, non-native and native fishes.

The Eastern Asiatic Freshwater Clam’s great success is distribution is attributed to the importation and commercialization of Asian Carp, its native Asian host (which is now found worldwide as well). Most likely the mussels arrived as larvae attached to the gills of these imported fish.

An additional possible direct means of dispersal is its being unintentionally marketed and sold by garden centers and aquarium shops as a species for biological control and water purification in several European countries. Invasive populations in Indonesia are considered as an important protein source and has significant economic value.

You never know what you’ll find in a ditch on the side of the road, and this mollusk made for a fun discovery.

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While catching tadpoles in the pond across the street from me, I’d occasionally net what looked to be a small tan pebble. Closer examination revealed something different though. Fingernail Clams, also called Pill Clams or Pea Clams, are members of a family of small to tiny freshwater clams that are common, but rarely noticed.

Like other clams, Fingernail Clams have two mirror-image shells that are hinged together that are generally rounded to triangular in shape. Their shells are thin and fragile, often translucent, the outsides typically shiny, fairly smooth, and gray, tan, yellowish, or whitish. Fine growth lines are often visible, but they are not strongly raised, ridged, or rough.

Fingernail Clams are found in a variety of aquatic habitats, usually in places with mucky or sandy substrates, and usually at or just under the bottom substrate. Some species of fingernail clams are adapted to live in vernal pools — temporary ponds, usually in woodlands, that fill with water in Springtime, then dry up during Summer. As the pool dries, the Fingernail Clam burrows down several inches into the soil, where it is moist enough for it to survive until the next Spring.

Like other clams, scallops, mussels, oysters, and most other bivalve mollusks, they are filter feeders that remove suspended organic materials from water, such as algae, tiny planktonic animals, and plant and animal detritus.

They have tubelike siphons that draw in water and tiny, drifting food particles into their shell cavity. A pair of flaplike, mucous-covered gills collects the food and channels it into the animal’s mouth.

Like its relatives, the Fingernail Clam has a foot, which is used to dig down into the pond bottom where it can burrow. Fingernail Clams (like most other mollusks) are hermaphrodites: each individual can produce both eggs and sperm. Fingernail clams are able to fertilize their own eggs.

Apparently Fingernail Clams can move from one isolated vernal pool to another by clamping on to a finger or toe of a salamander, frog, or other animal. Since they can fertilize their own eggs, only one individual can start a population.

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While tidepooling on the California coast, I came across a few of these cool mollusks. This species occurs in the Pacific Ocean from Oregon to Santa Barbara Islands, California.

With its smooth, conical shell, a brown turban snail looks like a “foot” wearing a large hat. The shell, usually covered with red algae, is orange or bright brown.

This herbivore is common in the low intertidal and shallow subtidal areas, and is most commonly found on kelp, upon which it feeds. When an individual dies, the shell is often rapidly utilized by hermit crabs, which use the hard shells to protect their soft abdomen. If you see a brown turban shell rapidly moving across the reef, it is occupied by a hermit crab.

If a Brown Turban Snail is dislodged from an irregular rock bottom, it can readily right itself, but on a gravel bottom it uses pebbles as a tool. It picks up pebbles with the front of its foot and transfers them to the back part of its foot. This changes the snail’s center of gravity, enabling it to roll over and right itself.

Like other snails and slugs, to feed it uses a radula (belt-like organ with numerous teeth on it) to rasp away the surface layer of tissue on blades of kelp and other algae.

Italian chefs serve these snails cooked in oil and served in their shell. They are removed and eaten with a pin. Brown Turban Snails are important prey species for predators including Sea Otters, Octopuses, Rock Crabs, and Sea Stars. They are able to sense chemicals that are released from some predators and flee towards shore in response.

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While doing some San Francisco Area tidepooling, we came across a few examples of this colorful creature. This pink nudibranch brightens local tide pools. Nudibranchs, also called sea slugs, are sea snails without a shell.

This stunning creature is named for its vibrant, rosy-pink coloration, which it gets from its diet of pink encrusting bryozoans, just like flamingos get their flamboyant pink hue from the shrimp they eat. The Hopkin’s Rose Nudibranch is found in the intertidal zone, where it can be seen on rocks, pilings, and other hard surfaces.

It is most common in the warmer waters of Southern California, but its range extends from Northern Baja California, Mexico, to the lower Oregon coast. Historically, it was rare to see Hopkin’s rose nudibranchs north of San Francisco, but in recent years they have become more common in southern Oregon.

Many nudibranchs wear bright colors that may warn predators that they taste bitter or foul. Usually the only animals that eat nudibranchs are other nudibranchs. The name “nudibranch” means “naked gill,” and the feathery gills of these animals take many fancy forms.

The species grows to be about an inch long and is nearly weightless. Like other marine gastropods, this nudibranch has a flat, muscular “foot” along the ventral or bottom side of its body that it uses to crawl along the substrate.

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While tidepooling in California, I came across this fine creature. Also known as the Giant Western Fiery Chiton or the Giant Pacific Chiton, it is the largest of the chitons, growing to 14 inches and capable of reaching a weight of more than 4 pounds.

This creature is found along the shores of the northern Pacific Ocean from Central California to Alaska. It inhabits the lower intertidal and subtidal zones of rocky coastlines.

The Gumboot Chiton’s appearance has led some tidepoolers to refer to it, fondly, as the “Wandering Meatloaf.” The name “Gumboot Chiton” seems to derive from a resemblance to part of a rubber Wellington boot or “gum rubber” boot.

Chitons are mollusks that have eight armored plates running in a flexible line down their back. Unlike most chitons, the Gumboot’s plates are completely hidden by its leathery upper skin that usually is reddish-brown or brown, but occasionally is orange in color.

Chitons have long arrays of fine teeth that are partially made of magnetite, making them hard enough to scrape algae off rocks. The Gumboot Chiton’s underside is orange or yellow and consists mostly of a large foot similar to that of other mollusks such as snails or slugs, with gills found in grooves running along the outer edge of the foot.

The Gumboot Chiton has a lifespan of more than 40 years.

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I often find these creatures around the edges of my garden on rainy Winter days. They are most often under rocks, logs or tarps. I suspect that they get flooded out of their burrows and surface for a bit before going back underground.

This species is almost exclusively restricted to cultivated areas, usually in open habitats, meadows, near roadsides, in ruins, gardens and parks – but it is not found in forests.

Also known as the Grey Field Slug or Grey Garden Slug, it is native to northern Europe, North Africa, and the Atlantic Islands. It was introduced into North America and now occurs across the continent. It is most common in southern Canada and the northern United States.

Like many of its relatives, the Milky Slug is active at night. During the day it remains concealed in the ground. It does not burrow, but uses existing crevices and worm holes. After dark, it climbs onto vegetation to feed.

It is wide-ranging in its diet, consuming beans, celery, corn, broccoli, cabbage, cauliflower, kale, radish, turnips, pumpkin, squash, lettuce, peas, spinach, and more.

When at rest, its body is contracted and the tentacles are retracted. When disturbed, it exudes white mucus over its entire body, leading to its common name.

Slugs are hermaphrodites; every slug is born with both male and female reproductive parts and any slug is capable of laying eggs; self-fertilization can also occur.

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While tidepooling in Central California, I found this clam. It is native to the Pacific Ocean from Baja California, Mexico to the Aleutian Islands, Alaska. The Pacific Littleneck Clam has a chalky shell that ranges from round- to oval-shaped and is a maximum of 3 inches long. Its shell is very heavy, and this species is sometimes called the “Rock Cockle” because of its strong radiating ridges.

This species is fast-growing and is often harvested in the wild by hand for cooking in chowder. On a wider scale, it is a popular edible clam which is commercially fished in some areas.

Pacific Littleneck Clams are poor diggers that not burrow vertically, due to their short siphons and feet. Thus, individuals remain close to surface of the substrate where they easily burrow horizontally. Since it is a relatively slow digger, it is not found in areas with unstable sand.

In 1885, this species was introduced to the East Coast of North America. The clams were brought from Oregon and Washington and planted near Woods Hole, Massachusetts, but they did not survive and were never found in the surrounding area.

The Pacific Littleneck Clam is also known as the Littleneck Clam, Common Pacific Littleneck, Rock Cockle, Hardshell Clam, Tomales Bay Cockle, Rock Clam, and Ribbed Carpet Shell.

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While exploring a creek near Youngstown, Ohio, I came across this cool creature.

The Wavy-rayed Lampmussel occurs in small-to-medium sized shallow streams in and near riffles with good current. It rarely occurs in rivers. Its substrate of preference is sand and/or gravel.

Its shell color ranges from yellow to yellowish green with numerous thin, wavy green rays. It can reach four inches in width and can live up to 20 years. Like all mussels, this species filters water to find food, such as bacteria and algae.

Mussels in general are rather sedentary, although they may move in response to changing water levels and conditions. Mussels insert their “foot” (seen here inside of shell) into the sand or gravel and pull themselves forward, inching their way along the creek bottom.

Belonging to a group known as bivalves, this mollusc is completely enclosed by a shell made of two valves. A hinge ligament joins the two halves of the shell together and large adductor muscles between the two valves hold them closed.

Mussel larvae are parasitic and must attach to a fish host, where they consume nutrients from the fish body until they transform into juvenile mussels and drop off.

The Wavy-rayed Lampmussel’s fish hosts are the Largemouth Bass and Smallmouth Bass. The presence of fish hosts is one of the key features for an area to support a healthy mussel population.

In turn, mussels are ecological indicators. Their presence in a water body usually indicates good water quality.

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In Central California this is often the most common sea slug around, though this impression may be due to the fact that its orange coloration makes it one of the easiest to find.

While the body shape is consistent, there are several color forms associated with age: the smallest often appear pure orange, medium individuals (1-1/2 inches long) are dark brown with white spots and large examples (3 inches) are light orange with distinctive white spots.

This species lives in the eastern Pacific Ocean, from Vancouver, British Columbia, Canada, to Baja California, Mexico. It also lives in Japan. It feeds on bryozoans.

It was neat to experience this a shell-less marine gastropod in the wild.

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