Common Name: Sitka Periwinkle
Scientific Name: Littorina sitkana
Size Range: Up to 2cm (0.8 inches) long
Identifying Features: The Sitka Periwinkle generally has a brown or grey shell, which is sometimes striped. They can close themselves inside their shells with a door, called an operculum. They slide around in their own mucus using their muscular foot. They have little eyes, antennae, and a mouth, which is full of tiny razor sharp teeth.
Habitat: Sitka Periwinkles attach themselves to pilings, mangroves, seaweed, rocky shorelines, and beneath boats and docks using mucus. They are one of the few sea creatures that can breathe air, and when the tide is low, they close themselves up into their shells to prevent drying out. Despite this ability many end up dying due to drying out especially when exposed to high temperatures. They live on the Pacific Ocean, from Alaska to Baja, and also on the Atlantic coast.
Food: Sitka Periwinkles are vegetarians. They feed mainly on filamentous algae but also eat films of diatoms, lichens and Rockweek (Fucus gardneri) . They scrape food off of surfaces with a hooked, chainsaw like structure of teeth called a radula. Impressively, they can replace up to seven rows of teeth daily! Most Sitka Periwinkles only eat every 2-3 weeks.
Predators: Many animals prey on the Sitka snail, such as sea stars, crabs, sea anemones, and various water birds. One study found the main predators to be the Red Rock Crab (Cancer productus) and the Pile Perch (Rhacochilus vacca). To protect themselves, the snails close themselves into their thick armor like shells. Many hermit crabs will use the empty shell of the Sitka Periwinkle as their home.
Life Cycle: Once yearly, males seek out mates. Often they can’t tell the difference between females and other males, and sometimes two males can be seen fighting, only to discover that the supposed female is in fact another male. Once fertilized by the male females lay 50-400 eggs in mucus bundles in tide pools. Once hatched, larvae are washed out to sea to grow. Young periwinkles look like miniature adults.
Pacific Wingfoot Snail
Common names: Pacific Wingfoot Snail, Sea Butterfly
Scientific name: Gastropteron pacificum
Size Range: to 33mm (1.3 inches) in length
Identifying Features: The Sea Butterfly has a shell-like appearance. Its foot and swimming lobes are a yellow-ocre color and it has clusters of red-purplish dots all over its body. When viewed up close the main body appears translucent.
Habitat: You will often find young individuals of Gastropteron pacificum swimming erratically in open water using a flapping motion of their lateral foot lobes. They can be found from the surface of the water to as deep as 30 meters below sea level from Alaska all the way along the western coast to San Diego, California. Despite the pelagic nature of the young of this species it lives mostly a benthic life. It moves about on the sea floor in soft sediment and looks much like a regular snail with its lobes folded over its body.
Prey: Plankton is the only known prey of the sea butterfly, although there is research being done to find other food sources of this species.
Predators: The only known predator that has been recorded is the Cephalaspidian mollusk Navanax. Contact with predators can induce G. pacificum to begin swimming away using its lateral foot lobes.
Pacific Wingfoot Snail at Victoria High School: A Pacific Wingfoot Snail was collected in open water in Cadboro Bay in a plankton tow in October of 2011. It was kept in our Seaquaria in the classroom for 5 months. During this time it was rarely observed swimming though it did swim on occasion when it was disturbed. It was not directly observed feeding but may have fed upon frozen brine shrimp used to feed the other aquarium inhabitants.
Video by Shelbie Montagnaro and D. Young
Photos by D. Young
Monterey Sea Lemon
By Anna Stürgkh
Common name: Monterey Sea Lemon, Sea Lemon
Scientific name: Doris montereyensis (Archidoris montereyensis)
Size range: 4.4 cm (1.7 inches) to 15 cm (6 inches) in length and 4 to 5 cm in width.
Animated GIFs by Lia Glidden
Identifying Features: The Monterey Sea Lemon (Doris montereyensis) is a distinct looking nudibranch with its bright yellow colour however it is easy to confuse with the Noble Sea Lemon (Anisodoris nobilis). Both have a similar shape, are bright yellow, have distinct tubercles (bumps) on their dorsal side, have feathery gill plumes, and may have a varied pattern of dark spots on their dorsal surface. There are a number of features that can be used to tell them apart. D. montereyensis is often described as having a “dingy” colour and is the one that has dark spots on the tips of the tubercles. A. nobilis in contrast is described as having a “clean” colour. It generally has a white gill plume, particularly on the outer edge of the plume, and the dark spots if present are only found between the tubercles.
Habitat: The Monterey Sea Lemon is commonly found on the west coast of North America. Its habitat reaches from southern Alaska to southern California. It can be found intertidally and can live in depths of up to 256m. This nudibranch prefers shaded and rocky regions. It is often found in areas with Bread Crumb Sponges.
Food: The Monterey Sea Lemon preys only on sponges, such as Haliclona panicea, which are commonly known as the Bread Crumb Sponges. These sponges provide the sea lemon with its yellow colour (it is not surprising that the similarly coloured A. nobilis also feeds on the Bread Crumb Sponge). The nudibranch uses its rough tongue (radula) to rub small pieces off the sponges.
Predators: Similar to other nudibranchs the bright yellow colour suggests that the Monterey Sea Lemon has chemical defenses and is a warning to predators that they should be avoided. The predation on this species is not well known. In captivity in our school aquarium a Pacific Spiny Lumpsucker took a bite out of the Monterey Sea Lemon but promptly spat it out.
Life Cycle: The Sea Lemon is a hermaphrodite. It reproduces throughout the year. It lays several eggs in capsules and the capsules come together to form a yellow chord, which can keep up to 2 million eggs. After the eggs are laid, the sperms that are stored in a “seminal receptacle” become agile and fertilize the eggs. The larvae hatch after about 23 days.
Photographs by Anna Stürgkh, Erin Pringle and D. Young Read more
Identifying Features: The Hooded Nudibranch can be up to 10 cm long, 2.5cm wide and 5cm across the expanded oral hood. The Hooded Nudibranch is a translucent white, yellow, orange, or greenish organism. It has a quite noticeable round oral hood for what could be seen as a “head”. Another feature to note, is that they are more gelatinous than a typical sea slug. When the hooded Nudibranch is taken out of water it gives off a sweet fruity aroma.
Habitat: Hooded Nudibranchs have been seen to live near low tide waters and in kelp forests in deep waters. They are commonly found clinging to eelgrass with their large foot, but they are also found on different seaweeds such as the blades of the Giant Bull Kelp. It is typical to find them from 0- 328m in depth. From what I have seen in the aquarium, the Hooded Nudibranch does not seem to be bothered by sharing its habitat with the many other marine organisms.
Food: The Hooded Nudibranch is a carnivore. They attach themselves to the under-water grasses, for example, and once the they feel their prey the fringes of the tentacles overlap, which then holds the prey and forces it into the mouth. The food then moves through the esophagus to the stomach. The Hooded Nudibranch constantly feeds as long as food is present. They eat small fish, small molluscs, and other invertebrates such as copepods, and zooplankton.
Predators: Predators of the Hooded Nudibranch would include fish, kelp dwelling crabs and sea stars. A quite unique defence for the Hooded Nudibranch is how they are to drop one of their cerata to distract the predator for just enough time to get away. Hooded Nudibranchs are quite entertaining swimmers as they flex their body in a side to side rhythm upside down to escape.
Life Cycle: Hooded Nudibranchs are hermaphrodites. This means that each one has both male and female reproductive organs. When reproducing, two would fertilize each other and then lay their eggs on, most commonly, kelps. Hooded Nudibranchs internally fertilize which is quite rare. Their eggs are tightly coiled in cream or yellow-coloured coil or wave like folds. Hooded Nudibranchs live for approximately a year and die once they lay their eggs.
Common name: Golden Dirona Scientific name: Dirona pellucida Size Range: up to 12 cm (5 inches) long
Common name: Golden Dirona
Scientific name: Dirona pellucida
Size Range: up to 12 cm (5 inches) long
Identifying Features: Dirona pellucida belongs to the Nudibranchia family. It has an eye-catching orange to red-orange color and has white specks on the tips of its cerata (the spiky leaf-shaped structure that covers its back). The cerata aids in the nudibranch’s respiration, but it also is used for defence. Unlike the D. pellucida’s back, its stomach is smooth and almost translucent.
Habitat: Golden Dironas live in the intertidal zones of the oceans, to depths of 60 meters. They can be found in tides from North Sound, Alaska to Puget Sound, Northern Washington, across the Bering Sea until the eastern seas of Japan, Korea and Russia.
Food: Golden Dironas are ectoproct feeders, specifically the bryozoan Bugula pacifica. We sometimes find them on top of sea sponges, not feeding from them but hunting for bryozoans from on top of them. Golden Dironas at times are spotted to be eating other things besides bryozoans as they sometimes feast on hydroids and ascidia.
Predators: The Golden Dirona has a lot of predators. Due to its flashy colour it attracts attention very easily, and its lack of a protective shell makes it vulnerable to predators. Its enemies range from crustaceans to birds and large fishes, depending on where it is located. Like many nudibranch’s the bright coloration of D. pellucida likely indicates to predators that it is toxic. If attacked they can detach the cerata from their back to distract the predator while they attempt to get away. As a result some individuals may have a large number of their cerata missing.
Life Cycle: D. pellucida is a hermaphrodite; it has both male and female organs. Once ready to reproduce they seek out to find partners, but despite having both organs having them self-fertilize is very rare. Instead they fertilize each other’s eggs with each other’s sperm. They then lay eggs in an egg ribbon. The eggs would then become trochophore larvae and then develop into vertilar larvae. This is when they hatch and leaves the security of where its parent laid it. The vertilar larvae would then undergo metamorphism and turn into a juvenile. It looks exactly like an adult minus the size and the fact that it isn’t sexually mature.
Behaviour: Many species venture out onto the surface of tide pools when the tide is out and the pools are very calm. They are likely just cruising around looking for food. They can easily hang by surface tension because they have almost neutral buoyancy (no shell to drag them to the bottom).
Photography by Samantha Claver
Interesting resources for research and photographer credit
Victoria High School
1260 Grant St.
Victoria. BC, Canada