Author: Rose Desi-Seulean
Arctic Cookie Star
Common Names: Arctic Cookie Star
Scientific Name: Ceramaster arcticus
Size Range: 11cm (4.2in) across
Identifying Features: The Arctic Cookie Star is typically pink with darker red accents in color. The arms and disc is bordered by large marginal plates. The Arctic Cookie Star is pentagonal, rigid and its arboreal (top) surface is usually covered with small flat-topped plates.
Habitat: Most Arctic Cookie Stars tend to live close to shore, typically interdial to 186m (620 ft.). They can be found around the Aleutian Islands (Attu) and anywhere from Alaska to the Strait of Juan de Fuca, south of British Columbia and into Washington State.
Food: Arctic Cookie Stars prey upon various species of sponges including the Peachball Sponge (Suberites montiniger). They also eat shellfish, mussels and mollusks.
Predators: Sunfish, sea turtles, manta rays, sharks and larger starfish are a big threat to the Arctic Cookie Star. Humans also are a big threat to most sea life whether it’s a souvenir they steal from the beach, an oil spill or just simply littering, we are definitely harming the Arctic Cookie Star.
Life Cycle: Like most sea stars, the Arctic Cookie Star reproduces through external fertilization. Sperm is first produced in the testes of the males and eggs are produced in the ovaries of the females; Cookie Stars are not hermaphrodites. Both gametes are shed in open water, where fertilization takes place. The larvae, which have bilateral symmetry, swim around for sometime and then swim to the ocean bottom where they develop into adults that have radial symmetry.
Author: Yunfei Gong
Common name: Vermillion star
Scientific name: Mediaster aequalis
Size range: 5 inches
Mediaster aequalis is one of the smallest sea stars ranging in size from three to seven inches. It is a red, 5 armed (rarely,4 to 6 armed specimens) star with a distinctive round texture on its surface. This sea star is named because of its bright color. It is vermillion aborally and more orange on the oral side.
Mediaster aequalis is found along the west coast of North America, ranging from Alaska to California. It is found on many types of beaches at very low tides, particularly on negative tide. The Vermillion Sea Star is common in shallow subtidal waters down to about 160m depth. It is often found on rocks shell, sand, gravel, pebbles and mud.
The Vermillion Sea Star eats a variety of living prey such as sponges, brachiopods, worms, bryozoans, tunicates and the Ptilosarcus gurneyi. It also scavenges dead animals and consumes detritus. Similar to other sea stars, they flip their stomachs out through their mouth and onto the prey they are eating. After selecting enzymes onto its prey and digesting it externally, it pulls its stomach back into its body again.
Sea stars do not have many predators because their outer skin is quite tough. But they do have some predators such as sharks, sea otters and other large fish and sea birds. They can curve their arms and turn into a ball to protect themselves. They also have the ability to regrow their arms if they are eaten by predators.
Sea stars can reproduce in both sexual and asexual ways. Vermillion Sea Stars reach sexual maturity within four years. As sea stars the males and females are in separate individuals. The eggs which are 1 to1.2mm are bright opaqe orange.
Photos by Yunfei Gong
The Stiff-Footed Sea Cucumber is white to cream coloured with eight large, yellow tentacles and two smaller ones which are used to collect food. This sea cucumber has tube-like feet covering its whole body. The size of the cucumber can vary from 4 cm to 10 cm long and its body wall is poisonous to certain types of fish.
This creature can be found under and between rocks along the coasts from Alaska to California. They are often found living in shallow rocky areas and underneath docks. They are also commonly found along the underside and edges of floating docks.
With its mucous covered tentacles, the Stiff-Footed Sea Cucumber is a filter feeder that collects small particles such as plankton and small decaying organic matter for food. It generally does this by holding its tentacles in the current and filtering out food items that stick to the “tree” of tentacles. It then takes each tentacle (which is a modified tube foot) places it into its mouth and takes the food off of it. It then withdraws the tentacle and places it back in the current.
The main predator of these sea cucumbers is the sea star Solaster stimpsoni.
Sea cucumbers are either male or female and they reproduce by releasing sperm and eggs into the ocean water. Spawning occurs in the spring and the egg, embryos and larvae are greenish in colour. The egg is inserted into a pouch on the adult’s body where it develops and eventually hatches from the pouch as a baby sea cucumber.
Sand Dollar Author: Molly Simpson and Emma Troost Common Name: Sand Dollar Scientific Name: Dendraster excentricus Size Range: Up to 10cm in diameter
Author: Molly Simpson and Emma Troost
Common Name: Sand Dollar
Scientific Name: Dendraster excentricus
Size Range: Up to 10cm in diameter
Sand dollars have no front, back, head or tail; instead they have a bottom (oral side) and a top (aboral side). They are round disc-shaped creatures that have a diameter generally about 10cm when fully grown. When living, sand dollars are dark purple/black in colour but after death they turn a creamy white. On their aboral side there is a symmetrical design that resembles a flower with five petals. The shell, called a test, is penetrated by small brown spines that give it a velvety look and enable movement.
Sand dollars live in the Pacific, Atlantic, and Arctic oceans. They live in the sand in the intertidal zone, around 90m deep. They live in groups, called beds, of varying sizes with as many as 625 in one square yard of sand. They prefer sheltered bays, sandy lagoons, or otherwise the shallow water of the open ocean. Generally you will find sand dollars along the North American east coast, or in British Columbia, Siberia or Japan.
Sand dollars eat algae, fragments of organic material, crustacean larvae, diatoms, copepods, and detritus. In calm waters, sand dollars use a method called suspension feeding to eat. In suspension feeding, they position themselves so that one edge of their test is buried in the sand and one is sticking up so that the hole on their oral side (their mouth) is right above the sand and they can catch food sitting or moving on the bottom. Sand dollars have 5 teeth set up in a symmetrical pattern in a structure called an Aristotle’s lantern. It can take them 15 minutes to chew their food and up to 2 days to digest it. They have spines which enable movement. The spines have fine hair like cilia on them that are coated with mucus and bring smaller food to the mouth. They also have tube feet, which are small suction cup like tentacles about as small as their spines. They use these tube feet to help them move around and bring larger food to their mouth.
Sand dollars, being slow, have many predators, including snails. Their main predators are: the large pink sea star, the Starry Flounder, the California Sheep Head, sea gulls, crabs, otters, and octopuses. To protect themselves they dig into the sand where they won’t be found by any of their predators.
Sand dollars live anywhere from 8-13 years; you can tell how old they are by the growth rings on their test. When spring begins the mating cycles begins too. Once the salinity and temperature of the water is just right the females release their eggs and the males release their sperm. Once sperm and egg meet they immediately develop into larvae via cell division. After a month of floating the larvae settle into the sand and start growing a test to become adults.
How to find and preserve a sand dollar test: The best time to find sand dollars is after a large storm when they wash ashore and die, leaving a white shell, called a test, behind. To prevent them from stinking put them in a diluted bleach solution and let them sit for about 15 minutes. Afterwards rinse them off, let them dry, and you have a beautiful white sand dollar test! Live ones should of course be left in the ocean.
Red Sea Urchin
By Victoria Cholak
Common name: Red Sea Urchin
Scientific name: Strongylocentrotus franciscanus
Size range: Its test can be up to 17 cm (6½ inches) wide and its spines up to 7.6 cm (3 inches) long
Identifying Features: Like all sea urchins, the Red Sea Urchin has a round circular body. The body hides inside a hard shell that surrounds the body all around, called test. Red Sea Urchin’s test can be up to 6½ inches (7.6 cm) wide. The test ranges in colours from acidic red to purple. The test also has long spines attached to it. The spines tend to be darker than the test and can be up to 3 inches (7.6 cm) long. Sea urchins in general, have tiny holes in their tests. Thought these holes come through their tube feet. Sea urchins use those feet to move around and catch things.
Habitat: Red Sea Urchins can be found on both rocky shorelines where there is a lot of wave action and on quite shores. The red sea urchins live in low intertidal zone, 91 meters deep. Usually, Red Sea Urchins can be found in similar places as the Purple Sea Urchin, ranging from Japan and northern Alaska to northern Mexico.
Food: All sea urchins eat seaweed. The red Sea Urchins eat specifically the brown and red seaweed. Sea Urchins in general use tube feet to pass the food that they fin into their jaws, where their 5 teeth chop the food. Then, the nutrients are swallowed and digested.
Predators: Like turtles, Sea Urchins have a hard shell called test. Its test may give the sea creature some protection from its predators, although it can not hide under the shell like turtles do. Red Urchin’s sea predators include: sea stars, sea otter, octopus, crabs, and wolf eels. In Japan, people eat the Red Sea Urchin’s reproductive organs as a delicacy.
Life Cycle: Red Sea Urchins fertilize in water column. After a period the fertilized eggs develop into larvae. It takes 6 to 8 weeks for the larvae to develop into juvenile sea urchins. Adult urchins can live up to be 7 to 10 years old.
Authors: Emma Grigg & Nastja Kharine
Common Name: Purple Sea Urchin.
Scientific Name: Strongylocentrotus purpuratus
Size range: up to 15 cm (6 inches) across.
Identifying Features: As in its name, the Purple Sea Urchin is purple but it can also be a purplish green colour. The Purple Sea Urchin is a medium sized sea urchin compared to its relatives the Green and Red Sea Urchin, measuring up to 15 centimeters across. It has a circular body covered in heavy spines. These spines cover the entire crust-like body acting as protective armor.
Habitat: Purple Sea Urchins are found from the coast of Alaska to the north of Mexico. They live in water up to about 160cm (63inches) deep on rocky coastlines. They use their spines to dig holes in pebbles, sand and rock to create a protective groove. These grooves are their homes and they shelter the urchins from crashing waves. Purple sea urchins like living with their friends and family, so you can usually find them in groups.
Food: The Purple Sea Urchin eats mostly algae. It has teeth that help it pull algae off rocks. They are also known to eat plankton, kelp, periwinkles, barnacles, mussels, dead fish and sea sponges.
Predators: Many things eat Purple Sea Urchins, even though they have huge spines. Crabs, sunflower stars, snails, sea otters, some birds, fish and people like Purple Sea Urchins on their menus.
Life Cycle: Purple Sea Urchins usually live up to 30 years or longer. They breed around January to March every year. The female sea urchins can produce up to twenty million eggs in one year. When the female sea urchins lay their eggs, the young urchins start off as larvae. It takes a few months for the larvae to develop into small baby sea urchins. It takes 2-5 years before a new sea urchin can reproduce.
Leather Star Scientific name: Dermasterias imbricata Size: Up to 30cm
Scientific name: Dermasterias imbricata
Size: Up to 30cm
The Leather Star (also commonly called the ‘Garlic Star’) is a five-legged echinoderm. The Leather Star often has light blue skin with reddish scales, and when rubbed smells faintly of garlic.
Dermasterias imbricata is found from the central coast of Alaska to northern Mexico. They generally live among the rocks in low intertidal zones, but can be found up to 300ft deep.
Leather Stars often feed on anemones, but will also consume sea cucumbers, sea urchins, sponges, chitons, and fish eggs. Sea stars feed by attaching to its prey using tube feet on the bottom of its arms. It uses its arms to pry open the victim’s shell, just wide enough so the sea star can squeeze its stomach into the shell. The sea star’s stomach comes out through its mouth, and once inside it’s prey’s shell, digests it, and retracts the stomach back into its mouth, leaving an empty shell. One has been observed feeding on the Stiff-Footed Sea Cucumber (Eupentacta quinquesemita) in our class aquarium.
Starfish do not have many predators, as their outer skin is quite hard, but manta rays, sharks, other large fish, and even certain types of snails will eat them. Larger sea stars are also a threat. The leather star uses its garlic-like odor to ward of enemies, and like many sea stars, has sensitive skin that can detect chemical changes in the water.
Sea stars can reproduce sexually and asexually. They reproduce asexually by dividing their bodies and regenerating missing parts. The decapitated starfish limb can grow into a new sea star, so long as a part of the central body portion is attached. In sexual reproduction, a sea star’s eggs are externally fertilized by a male sea star’s spermatozoa. The fertilized eggs develop into swimming larvae categorized into two groups: Bipinnaria and Brachiolaria. These larvae use cilia to move and eventually settle to the ground when growing into adults. When developing into a fully grown sea star, the larva’s left side will become its oral structures, facing the ground, and its right side will become it’s back.
Cushion Sea Star Common name: Cushion Sea Star, Slime Stars Scientific name: Pteraster tesselatus Size range: up to 25 cm (10 inches) in diameter.
Cushion Sea Star
Common name: Cushion Sea Star, Slime Stars
Scientific name: Pteraster tesselatus
Size range: up to 25 cm (10 inches) in diameter.
The Cushion Sea Star has a rounded pentagonal shape with a rigid and bumpy texture; they are very thick and resemble a pentagonal pincushion. A net-like pattern of small protrusions (ossicles-used for breathing) covers the top surface area, while suction cups (tube feet) cover the bottom. The stars can be red, pink, pale orange or purple. The young ones are usually green- brown.
These sea stars can be found in the Pacific and Atlantic oceans, ranging from upper-Canada to Central America. They mostly inhabit rocky areas. Young ones tend to be found in dense meadows of grasses or very rocky, uneven areas for protection.
Cushion stars are omnivores. They eat a variety of things from algae, diatoms, small detritus particles to clams and oysters, sea urchins, sponge tissue, crab larvae and other small organisms. In general, capture its food, the sea star will use their arms to force the prey close, then push their stomachs out the mouth and engulf the prey. The mouth is located on the bottom in the center and each arm contains 2 pyloric caeca tubes which branch from the stomach. These tubes secrete digestive juices and absorb the nutrients. The food then passes into the very small, short intestines which then pass through the anus.
Sea Stars generally have very few predators who are other animals as they don’t look very appetizing. However smaller sea stars need to watch out for larger ones who could possibly attack them. Some manta rays or sharks may be a threat to the sea stars. There are no specific predators found for the Cushion Star which were documented.
Currently the biggest concern for the Cushion Star is the environment. Throughout their habitats, they are being threatened by pollution, destruction and fishing. The coral reefs are also being threatened by global warming and acidification. Acidification is caused by increase of CO2 in the atmosphere, which raises the pH in the ocean.
Respiration occurs directly from water, through the ossicles. They then diffuse the water to obtain oxygen. This is why they are very vulnerable to water pollution; they don’t have the ability to filter out the waters contaminants.
Most Sea Stars do have a specific sex, male or female, which is not externally apparent; however some species can be hermaphrodites. Fertilization is usually external. To increase the chances of their eggs being fertilized, starfish may synchronize their spawning, forming in a group or forming pairs. This is called pseudo-copulation. Usually, the male climbs onto the female, placing his arms between hers, and releases sperm into the water. This stimulates her to release her eggs. Starfish may use environmental signals to time the spawning, and chemical signals to indicate their readiness to each other. When the gametes meet they form together the resulting embryos and larvae live as part of plankton.
In certain species the females brood their eggs either by enveloping them or by holding them in specialized structures. The developing young are called “lecithotrophic” because they get their nutrition from the yolk inside the structure, instead of planktotrophic feeding larvae. Brooding is especially common in polar and deep-sea Sea Stars that live in environments less favorable for larval development.
Photo courtesy of Andy Murch at www.elasmodiver.com
Interesting resources for research and photographer credit
Victoria High School
1260 Grant St.
Victoria. BC, Canada