Monterey Sea Lemon

sea lemon extra smallMonterey 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.

sea lemon diagram 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

Hooded Nudibranch

Hooded Nudibranch

By Maggie Ikeyima

Common names: Hooded Nudibranch and Lion Nudibranch

Scientific name: Melibe leonine

Size range: Up to 10cm long, 2.5cm wide and 5cm across oral hood.

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.

Read more

Gumboot Chiton

Gumboot Chiton

By Adam Kitzler and Niko Kruzel

Common Name:      Gumboot Chiton

Scientific Name:     Cryptochiton stelleri

Size Range:            Up to 13 inches (33cm) in length

Identifying features: Gumboot Chitons have an orange to yellow underside and their skin is normally dark. Unlike normal chitons the eight bony plates on its back are concealed. The Gumboot Chiton is the largest chiton in the world and has no eyes or tentacles; but sensory cells to help it navigate. It is very slow.

Habitat: Gumboot Chiton live on shallow rocks, where they can stick using there large foot so they don’t get swept off by the tide or large waves. They exist from the coast of California up to Alaska and down to Japan.

Food: Gumboot Chiton are herbivores and eat algae, sea lettuce and seaweed. They feed nocturnally with a radula.  Radulas are two rows of teeth that scrape the surface of rocks for algae, they resemble a sort of zipper.

Predators: Lurid Rocksnails and Seagulls will feed on Gumboot Chiton and occasionally Sea Otters and Sea Stars. The Chiton can roll up into a ball to protect itself.

Life Cycle: Gumboot Chiton can live up to 20 years and are dioecious. To reproduce the male gumboot chiton releases a cloud of sperm witch is the taken by a female, she them releases a long strand of fertilized eggs that are encased in jelly.

Read more

Golden Dirona

Common name: Golden Dirona

Author:  Samantha Claver

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

Read more

Giant Pacific Octopus

Giant Pacific Octopus

Author: Stephanie Hurst

Common name: Giant Pacific Octopus

Scientific name: Enteroctopus dofleni

Size Range: 3-5 meters and averaging 50kg (110lbs)

Identifying Features:

Giant Pacific Octopuses  as their name implies are found in the northern part of the Pacific Ocean. They are spotted anywhere from California up to Alaska and across to Japan.  They prefer living in the depths of temperate ocean water.  Similar to all octopuses Giant Pacific Octopuses are invertebrates, with distinct large bulbous heads, eight arms, and a beak made of calcium carbonate.  What sets them apart is their colouring and size. Giant Pacific Octopuses can grow to a length of 5 meters and weigh up to 50 kilograms. Generally they are a reddish-brown colour, they are capable of changing the texture of their skin and they have specialized cells call chromatophores that allow them to change their colour making it easy for them to camouflage into any surrounding.


The Giant Pacific Octopus’ preferred prey includes crabs, lobsters, shrimp, and clams. Time to time in some situations octopuses have been known to attack and eat sharks, and even other octopuses!  Octopuses are nocturnal hunters, and very stealthy.  Using their highly developed eye sight they look for motion from prey, when the prey ventures too close or the octopus get close enough it will ambush the prey using its strong arms to prevent it from escaping.  When eating, the octopus uses it strong beak to rip apart prey, and drill or bite into shells.


Even though the octopus seems invincible it does have some predators. Animals who like to make an octopus into a meal are large fish such as halibut and lingcod, as well as some marine mammals like sea lions and dolphins. There are two main ways octopuses can escape from predators, one way is through jet propulsion, giving them a burst of motion away from a predators. The second way is by releasing ink which temporarily blinds and confuses the predators.

Life Cycle (see the image below):

On average Giant Pacific Octopuses live 3-4 years. Females die directly after they have finished laying and guarding to their egg however males live a slightly longer time. Octopus reproduction starts when a male uses a specialized tentacle to pass two spermatophores (sperm packages) to the female. Once given the sperm the female stores the package until she is ready to fertilize the eggs.  Before a female is ready to fertilize the eggs she has to find a suitable den. This search can take the future mother up to one month! Once the perfect place is found the female shuts herself in using rocks. From there she fertilizes each egg and gathers them in bundle of approximately 200. She hangs each group of eggs from the ceiling of the cave. This is a long process because on average a female octopus can lay up to 50,000 eggs.  The incubation time for octopus eggs are six and a half months.  During this time the female stays in the cave, not even leaving to eat, attending to the eggs by constantly blowing oxygenated water on to them. When the baby octopuses hatch they are referred to as paralave. These tiny juveniles swim up to the surface joining other zoo plankton and spending weeks feeding on tiny phytoplankton. Once they have developed enough mass they descend to the benthic zone.  As for the mother, she waits until all the eggs have hatched then emerges from the cave and dies shortly afterwards due to the starvation she endured during the months she spent devoted to tending her eggs.

Photos by S. Hurst and A. Rutledge

Illustration of Octopus life cycle by Tatiana Neder


B.C. Royal Museum. (2010). Giant Pacific Octopus. B.C. Royal Museum. Retrieved January 4, 2012

B.C. Royal Museum. (2010). OCTOPUS REPRODUCTION. B.C. Royal Museum. Retrieved January 4, 2012

MLA Citation. ” Giant Octopuses, Enteroctopus dofleini at”. 4 January 2012.

National Geographic. (2012). Giant Pacific Octopus Enteroctopus doflein. National Geographic. Retrieved January 4, 2012.

SHIM. (unknown). Species and Habitat Outline; Giant Pacific Octopus. SHIM. Retrieved January 4, 2012

Frosted Nudibranch

The Frosted Nudibranch

by Elias and Jesse

Common name:  Frosted Nudibranch

Scientific name: Dirona albolineata

Size range: up to 180mm (18cm) in length

Identifying Features

Frosted Nudibranchs are soft bodied organisms similar to slugs. In the general, nudibranchs are often referred to as sea slugs. Frosted Nudibranchs can range anywhere from 20- 600mm long, but their most outstanding, and identifiable feature, is the frosty white tips on the cerata on their back. They come in a wide variety of colours, including mauve and peach, and for the most part, they’re translucent. The Frosted Nudibranch is known to shed its cerata when stressed.


The Frosted Nudibranch thrives along the shores of Japan, Siberia, and Southern Alaska, to Southern California. It is found intertidally and up to 37m deep.


Most sea slugs have very specific feeding needs, thus making them difficult to keep in aquariums. The Frosted Nudibranch has powerful jaws enabling it to crack open snail shells. This nudibranch has a vast selection of prey including arboresent and foliose bryozoans, hydroids, small prosobranchs, crustaceans, and ascidians.

Life Cycle

Nudibranchs are hermaphrodites. They have both male and female reproductive organs. In most cases, two separate organisms will exchange sperm. But there is a potential for self fertilization. Once the eggs are fertilized, they are laid in large amounts, often very close to a food source. Once hatched, they are in the trocophore larvae stage, characterized by a round shape, and numerous sensory and defensive hairs. The veliger larva stage is the stage in which young nudibranchs hatch. Eventually they abandon the water column, and travel to the bottom, becoming benthic. It is at this point, where they undergo metamorphosis, and become juveniles.

Read more

Blue Top Snail

Blue Top Snail

Author: Alisha Carey

Common name: Blue Top Snail

Scientific name: Calliostoma ligatum

Size range: up to 2.5 cm (1 inch) in diameter

Identifying Features:   The Blue Top Snai (Calliostoma ligatum) is part of the Callistomatidae family. It has a brown shell with tan to orange spirals. Its inner layer its pearly blue, and the foot of the snail is orange. When the outer layer of the shell is worn away the top of the shell (or the whole shell) may also look blue which is why it is called a Blue Top snail.

Habitat: Blue Top Snails are found in tide pools or up to 30 meters deep in the ocean. They can be found from Alaska to California. Blue top snails keep to rocky areas and kelp beds.

Food: C. ligatum eat a variety of algae and kelp. It eats by using its radula teeth (a ribbon with rasping teeth.)

Predators: The Blue Top snail protects itself by hiding within its shell. Some of their predators include shore birds, fish, crabs and other snails.

Life Cycle: In general, snails are considered sexually mature by the time they are one year old. The C. ligatum has both female and male organs. It produces eggs which it fertilizes inside. Then they release the eggs and they are attached to rocks and seaweed but some eggs can be found in the sand.

Photos by D. Young

Read more

Black Katy Chiton

Black Katy Chiton, Black Leather Chiton

Author: Sarayut Uddy Klongchoengrob

Scientific name: Katharina tunicata

Size: to 15cm in length

Identifying Features

The Black Katy Chiton is oval shaped and has 8 white over-lapping plates on top of its leathery black mantle. It can grow to around 15cm in length. It has a large muscular foot to help it move and in the mantle cavity around its bottom edge they have around 50-60 rows of gills called ctenidia that they use for respiration. Underneath the chiton you will see the head and mouth in front of the foot. It does not have any eyes or tentacles, but its shell has light-sensitive organs.


Black Katy Chitons are commonly found in the San Jaun Islands and Straight of Jaun de Fuca. They are found intertidally and occur up to around 40 meters in depth.  They are mostly found attached to rocks and they are unique compared to other chitons because they tolerate direct sun light.


Black Katy Chitons like other chitons, feed by slowly grazing on brown and red algae using a long rasping structure known as a radula. It is also known to have eaten small sponges and tiny barnacles.


Black Katy Chitons have only a hand full of predators such as sea urchins, the Leather Star (Dermasterias imbricata), and Oystercatchers (Haematopus bachmani). They avoid being eaten by blending in to their surrounding by being a really dark color with contrasting white plates which breaks up their shape.  Algae sometimes may grow on top of them allowing them to blend in more with their surroundings. They also have a hard mantle and can be tightly attached to rock making them very hard to remove.

Life Cycle

The Black Katy Chiton reproduces out the body where the male releases sperm into the ocean or in the mantle cavity of the female where the sperm would meet the egg. When the egg is ready it hatches into a free swimming trochophore larva. The larva then elongates and the shell gland secretes the plates of the shell. There is no intermediate stage.

Read more

Barnacle Eating Dorid

Barnacle Eating Dorid

by Hailey Surgin

Common Name:  Barnacle Eating Dorid
Scientific Name: Onchidoris bilamellata
Size Range: 6  mm(0.25 in) up to 30 cm(12 in)

Identifying Features:
Most Barnacle Eating Dorids have a mottled grey and brown colour to them. Their mantle, which is an outer layer of tissue that contains the viscera and secretes the substance that puts together the shell in other molluscs, has a brown and white pattern on it. Young dorids, and some mature adults may be completely white.  Towards the head are white club shaped tentacles called rhinophores.  They also have a circular gill plume near their posterior.

Throughout all the regions that Barnacle Eating Dorids live, they are all very similar. They are all sublittoral, which refers to a region that is near the shore where animals inhabit and grow as well as the area from the shore that reaches out to one hundred meters.  The depth of these areas can be up to twenty meters below sea level.

The Barnacle Eating Dorid, as mentioned in it’s name, really only eats one thing. Barnacles. The way that they eat the barnacles is by drilling into it with a specialized radula. Other parts of it’s diet also includes sponges, anemones, and coral.

There is little information about specific predators of this species.  However, when they are disrupted or disturbed, they secrete acids that act as deterrents.

Life Cycle:
Not a great deal of information is known about this specific nudibranch, but most nudibranchs are simultaneous hermaphrodites.  A simultaneous hermaphrodite is an organism that can mate with any other mature male or female of their species as they have both male and female reproductive organs.  When Onchidoris bilamellata reproduces, they come together in large groups to mate and lay eggs in shallow water.  The life span of a nudibranch varies widely. Some live for a month, whilst others can live for almost a year.


Read more

Opalescent Nudibranch

Opalescent Nudibranch         

by Allie and Charlotte

Common name :  Opalescent Nudibranch

Scientific name :  Hermissenda crassicornis

Size range :  up to 3″ inches long.

Identifying Features   

The Opalescent Nudibranch has a mid-line orange patch on its translucent back. It is slender and small in stature and is without shell or operculum. It also lacks a mantle cavity and is covered in many cerata topped with orange and white tips. Sometimes, the patch of vibrant colour on its back can be deep blue. The Opalescent Nudibranch has a yellow green body with a peacock-blue line around its sides. The pearly white tips of the cerata contain many defensive nematocysts.  The head has a pair of rhinophores (tentacles) and it lacks a gill plume near its back end.


The Opalescent Nudibranch lives on eelgrass beds, rocks, mud flats, docks, and certain other rocky intertidal areas from Alaska to as far as Baja California or even Kodiak Island and Japan. It is found from the intertidal zone to 115′ deep but it can live at virtually any depth of sea water. They thrive in shallow, warmer water and are larger and more common in these areas.

Food (Prey)

Nudibranchs feed on hydroids, sponges, sea slug eggs or sea slugs, sea squirts, pieces of fish, other mollusks and sometimes anemones and barnacles. All are carnivorous and feed on a wide variety of animals. The Opalescent Nudibranch is one of the few cannibalistic species of nudibranchs.


There are few if any documented predators of the Opalescent Nudibranch except for other cannibalistic Opalescent Nudibranchs.  Many nudibranchs have evolved to blend in with surrounding plants in order to avoid all predators while others have evolved to be brightly coloured to warn predators that they are or may be poisonous. They can also use an assortment of chemical defenses that make them toxic to predators that may include releasing a mucus-like acid from their skin when they come in contact with a potential predator.  The Opalescent Nudibranch is brightly coloured to warn off predators because the tips of its cerata are armed with unexploded nematocysts from hydroids it has eaten.

Life Cycle

Nudibranchs are hermaphroditic but are unable to fertilize themselves. They also tend to lay their eggs in a gelatinous spiral. The Opalescent Nudibranch is common, abundant, and has a life cycle of four months. Other species of nudibranches can live up to a year, and a 6 year life span has been reported when the nudibranch is inside an aquarium.

Read more