Crustaceans (arthropods) include the shrimp, isopods, amphipods, crabs, hermit crabs, copepods and barnacles. All have an external skeleton that must be molted for growth. The arthropoda is the largest phylum of animals with over a million identified species. Reproduction is by internal fertilization. Sexes are usually separate except in barnacles. Most retain eggs until hatching and have planktonic larvae.
Barnacle cirri: modified legs used for capturing food (plankton/detritus net)
Barnacles, like all crustaceans, have an exoskeleton that cannot grow with them. It must be molted to allow the development of a new larger skeleton. The skeleton is inside the house (rostrum). The house is continually remodeled and enlarged by the barnacle as it grows.
The giant barnacle is found only at the lowest of the low tides. It reaches 3 inches in diameter. This individual is covered with pink coralline algae and small red seaweed. It is inverted due to its position on the underside of the rock.
Black-clawed crabs are found under rocks a the mid intertidal level. They tend to become rigid when handled but can deliver a very powerful pinch for such a small crab. The black pigment in the pinchers hardens them. Food: Omnivorous: algae and small invertebrates Reproduction: sexual, internal fertilization, eggs carried by female, planktonic larvae, females mate when they have hard skeleton. (don’t need to molt to mate) Predators: Sea star, birds, larger crabs.
Eggs of black-clawed crab
Decorator crabs actively decorate themselves with various items. They are equipped with hair-like hooks to attach materials to. Food: scavenger(?) Little know of life history Reproduction: sexual, sexes separate, eggs carried, planktonic larvae. Predators: sea stars, fish.
Graceful decorator crab
Food: carnivore, scavenger - bivalves, fish other invertebrates. Reproduction: Sexual, separate sexes, females carry eggs, plankton larvae – females must molt to mate – males will hold females for a week or more before mating. Predators: Octopus, fish, other Dungeness crabs, sea otter
Two molts of Dungeness crabs
Females must molt for mating to occur. Males may hold females for up to a week before mating can occur.
Found in the high zone these small crabs have hairs on their legs. Color is variable but often green. This is NOT the invasive European green crab. Food is detritus and algae mainly but also feeds on eggs of whelks and other small invertebrates. Reproduction: sexual, separate sexes, females carry eggs, planktonic larvae. Predators: gulls, crows, fish, sea stars, larger crabs.Hairy shore crabs can tolerate any salinity level and are found in salt, brackish and fresh water. They are the dominant small crabs in estuaries.
Found in the high intertidal under rocks. Sometimes shares habitat with the hairy shore crab. Purple shore crabs have no hair on their legs which distinguishes them from the hairy shore crab. They are also found more often in more rocky areas as opposed to the mixed sand and rock and even mud of the hairy shore crabs habitat. Food: Mainly algae but will also feed on small invertebrates and the eggs of whelks. Mating: males grab females by a claw then flip over on their backs and pull the female on top of them. The male’s abdomen is used to open the females to gain access for mating. The male fertilizes the female by passing sperm via pleopods inserted into the females gonopore. Like their close relative the hairy shore crab they can tolerate wide swings in salinity.
The European green crab has been found on the outer coast and is considered a possible threat to the ecological balance of our waters. Surveys are currently underway to determine if this crab is in Puget Sound.
Usually found subtidally with only molts washed up on the beach. Sometimes will bury in the sediment. Food: Omnivorous: eelgrass, algae, small invertebrates. Reproduction: As with other crabs. Predators: fish, sea otters, seals
Molts are often found washed up on beach but live crabs are usually only subtidal.
Food: Kelp and other seaweeds, jellyfish and other invertebrates. Reproduction: As with other crabs Males have much larger pinchers than females. Males compete with other males for mating rights with females.
Eggs number between 34 and 84 thousand. Color is bright orange at first and turning to deep red at hatching. Larvae are planktonic.
Note the color difference from the other kelp crab in the earlier slide. These crabs store food (seaweed) on hook-like hairs on the front of the rostrum.
Look for black claw tips and very hairy legs. This is a smaller cancer crab related to the red rock and Dungeness crabs with the carapace reaching only about 2 inches in diameter. Food: generalist predator – barnacles, snails, bivalves, worms and some green algae.
No black on pinchers. Found low intertidal and subtidal. Can be confused with red rock crab but only grows to about 4 inches in diameter (carapace). Legs a slender and more graceful that in red rock crab. Food: generalist predator – worms, crustaceans, jellyfish, bivalves Predators – red rock crab, gulls, sea stars and fish.
Large cancer crab (second in size to Dungeness) with extremely powerful pinchers. Found in low intertidal and subtidal. Food: Predator and scavenger – barnacles, bivalves, snails, fish, sea cucumbers, sea urchins. Predators: Gulls, crows, sea stars, fish other crabs.
The red rock crab size change in one molting.
Male on top – female can only be mated after she molts. Internal fertilization (normal in crustaceans)
Juveniles are often very different colors and patterns than adults.
Common molt found on Puget Sound beaches
A type of decorator crab that is usually covered with sponge if anything. Does not do much active decorating but allows organisms to attach and cover it. Small hook-like hairs seem not to be used for active attachment. Food: detritus and small encrusting invertebrates
Found under rocks in low intertidal zone. Appears to be an omnivore feeding on algae, invertebrates; also filter feeds.
There are a number of hermit crab species that can be found on Puget Sound beaches. Most will be small. Different species use different species of snail shells for protection. Reproduction: Males and females extend part way out of the shells during mating. Males attach spermatophores around the female’s genital openings. Eggs are laid immediately after mating and attached to pleopodal setae on the female’s abdomen. Food: detritus and some scavenging
A very flat crab found under rocks in the mid to low intertidal. It will autotomize (drop off) limbs when attacked by predators. Food: Plankton, detritus…..filter feeder Notice this crab has only 8 appendages visible not 10. Its ancestors were likely hermit crabs that reduced their last pair of legs to use for attachment in the snail shell home. Last pair of legs are small but still present.
Another crab related closely to hermit crabs.
Isopods (equal legs) are the marine cousins of the backyard pill bugs. Some roll up into a ball others do not. All females have a pouch in which the eggs and young are carried.
Isopods come in a variety of colors some roll into a ball others, like these, do not.
Isopods found on eelgrass
The sea slater lives high in the splash zone and acts like the beach cockroach.
Ghost shrimp burrow into the sand. They are very abundant in sandy habitats (intertidal and subtidal) and provide food for gray whales in some areas of Puget Sound. Because their burrowing makes the bottom unsuitable for oysters they are the sworn enemy of the oyster growers and poisoned to control their numbers. insecticide sevin (carbaryl) which is used to control ghost shrimp in Pacific oyster beds is also very toxic to the Dungeness crab.
Many species of shrimp are found in tidepools and under rocks. They are mainly predators and scavengers. Eggs are carried under the abdomen.
Sand fleas, beach hoppers, are amphipods which means two kinds of legs. These are detritus feeders on decaying seaweeds. They get the flea name because of their ability to jump extremely well….they will not infest your dog or cat.
Mollusks – bivalves, snails, sea slugs, chitons, octopus – soft bodied animals usually protected with shells.
Hairy chitons have very thin, soft hairs on the girdle and are usually clean of hitchhikers.
Lined chitons feed on pink coralline algae.
Woody and lined chitons
Can be confused with the lined chiton.
The mossy chiton’s shells are surrounded by a girdle covered with thick, stiff hairs. This likely makes it more difficult for predators such as the sea star to get a good hold of the chiton. Mossy chitons are also often covered with algae and other organisms that attached to the shells.
The gumboot chiton is our only local chiton to have all its shells internal. Color is often dark red but variable.
The chiton has a mouth containing a radula (the feeding structure). The head is not well developed. Eyes if present are not complex and likely used only to differentiate light from dark.
The radula is the feeding structure of mollusks except for the bivalves. It is a tongue-like device studded with hundreds of tiny teeth. The rasping action of the radula is used to scrape off seaweed, drill holes and in some species of snails to harpoon prey. Gumboot chitons have a high percentage (51) of iron in their radula which may harden the teeth but may also allow the radula to act as a compass.
The gumboot chiton is the largest species of chiton in the world…..this is a good size one.
Gumboot chiton spawning (eggs). This is an example of broadcast spawning where eggs or sperm are released directly into the water. Young are planktonic.
Black Katy chiton cannot tolerated long periods of direct sunlight.
Clams feed through a siphon or siphons. The siphons channel water and plankton inside the clam where the gills filter out food and absorb oxygen. The filtered water is then passed out through the other siphonal opening The finger like projections help to keep out unwanted objects.
Many clams fall victim to the moon snail. Shells with holes like this one are moon snail victims. Some other predatory snails also drill holes with the radula.
The heart cockle is a shallow living clam that has hart shaped shells with viewed end on. It is also our only jumping clam. When attacked by a moon snail or sea star it will extend a very large foot and hop away across the bottom.
Horse clams are one of the largest found on local Puget Sound beaches. Only geoducks are larger in our area.
Horse clam – note the very untidy looking siphon.
Horse clam siphon
Oysters are rare on most Puget Sound beaches but occur were Summer water temperatures get high enough for spawning to occur. This is usually only in quiet shallow bays. Oysters are a major commercial shellfish on Washington’s outer coast where they are cultivated in the large shallow bays of the south coast. The Japanese oyster is the largest in our area and is an introduced species. The smaller Olympic oyster is native.
Jingle shells, or rock oysters at bivalves found attached to the underside of rocks in the intertidal. They attach with cement through a hole in the inside, smaller shell. Like other bivalves they are filter feeders.
Littleneck clams. There are two species locally: The Manila littleneck and the Pacific littleneck. The Pacific is round to oval and rather inflated looking while the Manila is elongated oval shape.
Littleneck clams, butter clams and cockles are common on local beaches but oysters are found only where water temperature is usually higher.
Butter clams have concentric rings and heavy shells. The siphon tips are black and can concentrate to HAB toxins. Butter clams are often the only species closed to harvest during a HAB alert. (HAB = harmful algal bloom) – what was once called “red tide”
Mussels attach to the bottom with stiff hair-like threads. The threads have extremely strong glue on the ends for attachment. If necessary the mussel can detach threads at the foot end and add new ones. This allows the mussel to actually move across the bottom or reattach if it becomes dislodged.
The rasp-like ends of the piddock clam are used to burrow into hard clay in the low intertidal. Like other clams they are filter feeders and broadcast spawners.
Piddock clams in hard clay burrows. Low intertidal
Single siphon is split into two openings near the end.
Not common on local beaches but sometimes found among the rocks.
Scallops upper shell is often covered with sponge which may be used as camouflage and protection against the attachment of sea star and octopus suction cups.
Shipworm (Clam) in piling
The shipworm (clam) is equipped with small drilling shells and long tube-like body and a pair of, feather-like plugs for the entrance to the burrow.
Bubble shell snails have a reduced shell…looks like they are sea slug wannabes. The egg case is left on the sand attached with a thread. It looks much like a blob of snot…..don’t know about the taste.
Bubble shell snail and egg case. The egg case is attached in the sand by a thread.
The dogwinkles are predators on barnacles and mussels. Three species are common on Puget Sound beaches. The Emarginate dogwinkle (Rock Whelk) drills holes in barnacles, mussels, limpets, and other snails. Predators include the red rock crab, and purple sea star. The eggs are eaten by some isopods, fish, and purple shore crabs.
The Dog whelk is a predator on barnacles, mussels, and other shelled animals.
Dogwinkle eggs are laid in capsules and attached to rocks in the intertidal. In two species the eggs are small and not very yolk filled. In these snails most of the eggs are ‘nurse’ eggs used by the first hatching snails as food. In the other species the eggs are large and yolky and there are rarely nurse eggs( Frilled dogwinkle). Eggs are prey of some isopods and ribbon worms and shore crabs.
The dunce cap limpet feeds only on encrusting coralline algae and have radular teeth caped with silica and iron for durability. Their predators include sea stars, crabs and fish. The growth of coralline algae in their shell helps to camouflage them from visual predators.
There are a number of intertidal limpets that look like shields. They are grazers on algae and most are found in the high intertidal area. They are known for their great homing skills. Predators include sea stars, birds, crabs and fish.
These tracks in the algal growth on the mussel shell were made by limpet radulas.
Moon snails feed on clams by drilling them with their radula. Larvae are planktonic. Moon snails fall prey to gulls, red rock crabs and sea stars.
The egg case of the moon snail (sand collar) consists of sand grains, cement and eggs. The eggs number up to half a million. Hatching releases planktonic larvae into the sea. Moon snails often lay the sand collars in the intertidal where they are common from Spring to early Summer.
The moon snail can retreat completely into the shell. It accomplishes this feat by pumping water out of its body.
Oyster drills are not native to Washington State but are now in some of our area oyster beds, especially the outer coast. The name says everything about their feeding habits. Due to the lack of oysters in our local area this species is not likely to be seen on Seattle beaches.
These little snails are vegetarians on various seaweeds.
There are two species of periwinkle snails in our area – the Sitka and Checkered periwinkles. Both are grazers on seaweeds. The Sitka lays eggs in a jelly mass attached to the rocks and the young are not planktonic. The Checkered releases tiny Frisbees, each with a few eggs, into the sea and the young are planktonic.
Keyhole limpets have a hole in the top of the shell and unlike other local limpets are predators. They are the largest limpets in our area.
Sea slugs are common and diverse in Puget Sound. The Lion sea slug traps zooplankton and other small invertebrates from eelgrass with an unusual oral hood.
Sea slugs are hermaphrodites and exchange sperm when mating.
The small opalescent sea slug feeds on hydroid and passes unfired stinging cells into its cerata where they are stored for use in the slugs defense.
Sea lemon – feeds only on sponge.
This small sea slug feeds on barnacles.
Only occasionally found intertidally.
Feeds on sea anemones, especially the aggregate anemone. Sting cells of the anemone are passed to the cerata and used in the slugs defense. Mating and egg laying takes place in Winter and early Spring.
Shaggy mouse with egg mass.
Commonly seen intertidally. Another sponge eater. There may be as many as 16 million eggs in the egg ribbon.
Feeds only on Sea Pens - Eggs look amazingly like its prey and are left on the sandy bottom.
Largest octopus species. Reaching a weight of over 400 pounds. Not commonly seen in tidepools but dens are sometimes in the low intertidal. Prey includes mollusks, crustaceans, and fish. Eggs are guarded by the female until they hatch in about 5 months, after which the female will die. Males also die after mating. Life expectancy is a short 3-5 years.
Seen in limited numbers intertidally. This small octopus has a nasty bite and should not be handled. The bite in venomous and can produce considerable pain and tissue damage.
Cnidarians – stinging nettle animals. Most have stinging cells and/or sticky capture organs. Includes: Sea Anemones, Sea Pens, Corals, Jellyfish, Hydrocorals, Sea Fans and Sea Whips.
Aggregate anemones include two forms. One form reproduces both sexually and asexually while the other form reproduces only sexually. It is not known if these two forms are the same species, or perhaps different life stages of the same species. Aggregate anemones are known for their belligerent attitude toward other clone colonies. Meeting different clone colonies will attack each other with special stinging batteries. This warfare usually results in an open space between two competing clone colonies known as “no anemone land”. Aggregate anemones house symbiotic algae that give the animal its green color. The symbionts produce sugars, some of which are leaked to the anemone and provide additional food. The remaining food needs come from prey items captured by the stinging tentacles.
Clone colony: either all male or all female. Divisions usually occur only once per/year.
Not usually found south of North Puget Sound. Mainly an outer coast species. Symbiotic zooxanthellae and zoochlorellae give the anemone its color. Symbionts provide sugars for the anemone. The anemone returns CO2 to the symbionts to be used in the construction of more sugars. Anemones keep in the dark (often in sea caves) are white due to the lack of symbionts. This anemone only reproduces sexually.
There are two species locally – a large and small. The small species reproduces sexually and asexually by budding from the foot (pedal disk). Tentacles and mucus are used to capture zooplankton prey. Color is white or tan.
Mottled anemones are the most common large anemones in the local intertidal. Color is tan, red or mottled red/green. Prey consists of a variety of invertebrates and fish.
Comparison – Mottled and Plumose anemones.
Hydroid colonies appear as hair-like strands attached to the underside of rocks. When in the water they appear to be delicate branched colonies of tiny hydroid polyps. These will bud off tiny jellyfish.
Largest jellyfish – bell diameter in our area reaches 2 feet but in other areas 8 feet. Capable of delivering a painful sting even when washed up on the beach.
Second largest jellyfish in local waters. Feeds heavily on other jellyfish, perhaps even the Lion’s Mane. Can deliver a mild/moderate sting to unprotected skin.
Sea Pens are octocorals: Each polyp has eight tentacles. This is a colonial animal where all polyps share a common gut. There is a division of labor among the different polyp types. Usually only subtidal but sometimes found in shaded areas (under piers) of the intertidal or washed up on beaches.
Echinoderms: Sea stars, sea cucumbers, sand dollars, sea urchins, brittle and basket stars. Echinoderm = spiny skin. Not all have spines but all have a water vascular system that uses hydraulic pressure to operate the tube feet. The skeleton in internal and called a “test”. Spines of some are moveable (urchin and sand dollars) and fixed on others (sea stars). In addition many have tiny pincher-like pedecellaria on the surface. These pinchers are used to keep hitchhikers are predators at bay. In at least one species of sea star (fish eating star) they are used to capture prey.
Feed on plankton and small invertebrates. Brood young (unusual for sea stars). Sea stars lack teeth and usually feed with the stomach everted from the mouth.
Brittle stars feed on plankton and detritus mainly but some are also predators. Unlike sea stars they have teeth. The body surface is covered with small calcite lenses that make up the extremely unusual visual system. Each of the single calcite crystals is in the shape of a double lens. It is possible that other Echinoderms use some kind of similar system of vision but research remains to be done in this area.
Brittle star straining plankton from the water. Food is capture by the tube feet and passed to the mouth by the feet in a mucus ball. Some brittle stars use their teeth to scrape food off rocks or may even form the arm into a loop to capture small invertebrate prey.
Giant pink stars are mainly subtidal but occur intertidally at very low tides. They prey on bivalves in sandy habitats.
Leather stars feed on sea anemones and other invertebrates. The texture is like wet leather and the odor is something like burnt gunpowder. The madriporite is located off center, as in other sea stars, and is the outside connection with the water vascular system.
One of the more common intertidal stars of Puget Sound. Food is barnacles and mussels and other small invertebrates. Predators include other sea stars and gulls. Color is variable.
Purple sea stars have a very solid test (internal skeleton). They are resistant to drying and can spend hours out of the water at low tide. Food includes mussels, barnacles, and other invertebrates. Color is variable. The are distinguished from the mottled star by their larger central disc in relation to the ray length. During the winter on the outer coast of Washington they move to deeper water and become inactive. In this way they avoid the heavy surf of winter storms. During spring aggregations of purple sea stars will be seen in shallow water where they congregate to spawn.
Sunflower stars are the largest species. They reach 3 feet in diameter. Rays (arms) are added as they grow with 24 usually being the maximum. They feed on a wide variety of invertebrates including, sea urchins, clams, mussels, oysters, crabs, and other sea stars. The test (skeleton) is composed only of scattered plates, making this sea star very flexible and soft to the touch. Speeds of 6-12 feet per minute make this the world’s fastest sea star. The surface is covered with many tiny pincher-like pedecellaria. If you place the back of you hand on the surface they will grab any hairs with these pinchers.
Rose stars are quick moving smallish stars that feed on sea pens, sea slugs, sea squirts, bivalves and also some other sea stars (mottled and six-rayed). In turn they are prey for the morning sun star and sunflower star. One researcher has determined that they can live at least 20 years and likely much longer. Young sea stars sometimes hide in the tubes of certain species of worms.
Vermilion stars are unusual in that they feed not only on sea pens, sponges, sea squirts, bryozoans and other invertebrates but also consume algae and detritus. They are sometimes paracitized by a barnacle that lives within the internal tissues. The morning sun star is likely the major predator of the vermilion star.
One of the most unusually colored sea stars. Background color is quite variable always with a blue-gray stripe radiating from the central disc our each of the rays. Main prey is sea cucumbers with lesser prey being sea squirts and sea pens. The morning sun star is its major predator. They can have 9 to 12 rays but usually 10.
Six-rayed stars are small often drab looking stars found under rocks intertidally. They feed on a variety of small or juvenile invertebrates. They are unusual as egg brooders. The fertilized eggs are held under the mouth in a sticky mass until the young hatch and crawl away on their own.
Green sea urchins are the only species normally seen on central or south Puget Sound beaches. Those found are usually small juveniles hidden under intertidal rocks. Urchins feed mainly on seaweeds but will also scavenge and even occasionally prey on other invertebrates. The jaws and teeth form a very complicated structure knows as Aristotle’s lantern.
Red and purple urchins are common in the Strait of Juan de Fuca and the outer coast of Washington. They feed mainly on seaweeds. Purple urchins often scrape holes in the rocky substrate with their spines and perhaps teeth. They are protected in their rocky burrows from the heavy outer coast surf. In some case they may become trapped in the holes they dig and must gather drift algae with tube feet to obtain food. Echinoderms are also capable of taking nutrients directly through the skin.
Sand dollars are common in sandy tide pools and into the subtidal. They have the widest zonation range of any local species. The outer surface is cover with tiny, movable spines use for digging through the sand. Food is plankton and detritus that is captured with the tube feet and passed up channels to the mouth. Like the urchins, they have 5 teeth. Both the mouth and anus are located on the underside (oral side).
Red or burrowing sea cucumber is always found under rocks or in rock crevasses with only the oral (feeding) end exposed.
Burrowing cucumbers feed with modified tube feet (oral podia). The podia are sticky and finely branched. Plankton and detritus picked from the water is removed from the podia as the are placed in the mouth and licked off.
The small white sea cucumber feeds in the same manner as the red (burrowing) cucumber but does not always burrow. It can be found subtidally on the top of rocks or sides as well as underneath. On beaches it is most likely to be found under rocks.
Usually not found intertidally but occasionally seen a extreme low tides. Our largest local cucumber.
The oral podia of the California sea cucumber are used as sticky mops to gather food and pass it into the mouth. During the fall it will absorb its internal organs and become dormant. In spring the organs will regenerate and the cucumber will become active. This sea cucumber can swim with a wiggling motion to escape predatory sea stars. It rarely eviscerates when disturbed but will under stressful environmental conditions such as oxygen depletion or high temperature.
Sponges are extremely simple animals with no organ systems and only a limited number of cell types. They filter plankton (often bacteria) from the water. Most intertidal sponges are found under rocks where it remains damp and cool at low tide.
Common on the underside of rocks in Puget Sound. Main food of sea lemon sea slug and some other dorid sea slugs.
Not usually seen in central or south Puget Sound but common in the Strait of Juan de Fuca and outer coast. Low intertidal on the upper surfaces of rocks.
Mostly subtidal but occasionally see a very low tides.
There are a large number of intertidal ‘worm’ species in Puget Sound. They belong mainly to five different phyla (major groupings): The Annelida (segmented worms), Platyhelminthes (flat worms), Nemertea (ribbon worms), Sipuncula (peanut worms) and the Chaetognatha (arrow worms). The arrow worms are planktonic in all life stages and are not covered her.
Calcareous tube worms are common on the underside of rocks in the intertidal. As the name suggests the tubes are of calcium (and other materials), hard and inflexible. The worms are segmented (annelid). All are filter feeding plankton eaters. There is a modified tentacle used as a plug for the tube entrance when the worm retracts. The cartilage plug also has a mucus coating that is likely used as an antibiotic to keep the tube opening clear of settling organisms; it may also have a lubrication function. The tube worms are prey of ribbon worms and sea stars. Reproduction is by broadcast spawning. Sexes are separate.
Our largest intertidal tube worm. The worm tube in the picture is a glass tube used in the Aquarium to exhibit the worm’s true form. Actual tubes have a leathery texture. The worm captures plankton with the tentacles that use a combination of mucus and cilia to move the food to the mouth. Food particles are sorted by size in gutters that run down the center of the tentacles to the mouth. Smaller items are sorted and eaten, medium size particles are captured and passed to sacks where they are later glued in place as part of the tube, and the largest particles are ejected back into the water as unwanted. The tentacles contain eyespots that allow the worm to react quickly to shadows and retreat into the tube for protection. Many tubeworms are broadcast spawners and are usually separate sexes. Other tube worms may brood the eggs and have not planktonic young. The exact method used by this worm is not known.
Flatworms are commonly found under intertidal rocks. They are predators on small invertebrates. As a rule flatworms are hermaphroditic but do not fertilize themselves. A few species have separate sexes. Internal fertilization is the rule. Most species larvae develop directly into bottom dwelling forms but a few species have planktonic larvae. The largest flatworm in our are reaches 4 inches in length and is occasionally found under rocks intertidally. The eggs of this giant flatworm are attached to rocks and hatching young crawl away.
The hairy gilled worm lives in a sand tube glued to the underside of rocks. The tube is delicate and often destroyed when the rock in overturned. Food is detritus picked up with long white tentacles and passed down the tentacles by cilia to the mouth. Often the worm will have guest living inside the tube – the armored scaleworm. The role of the scaleworm is not known but when observed outside the host tube it has been observed eating small crustaceans. Reproduction: Scaleworm – separate sexes, broadcast spawner, planktonic larvae. Hairy gilled worm – separate sexes, broadcast spawner, planktonic larvae.
No text – see previous slide
Sand tube worms ( or cement tube worms) – collect sand grains with their tentacles and cement them together to form the tube. The tentacles also capture food. They are often found in large clusters. Reproduction is by broadcast spawning, with planktonic larvae, sexes are separate.
This species forms clone colonies by dividing asexually. Sexes are separate. Sexual reproduction may be by broadcast spawning but in some species the eggs are brooded. On Puget Sound beaches they are found in the low intertidal attached to rocks. The colonies on the outer coast can be quite large, covering much of the surface of rocks. Food is captured with tentacle-like palps covered with cilia and mucus. These worms have much harder tubes than the sand (cement) tube worms.
These little annelid’s bamboo-like tubes are seen sticking out of the sand in large numbers on local beaches. The tubes seem to be evenly spaced on the beach. The tube may reach over two feet deep into the sand. Food is detritus and plankton.
The tusk worm is uncommonly seen on local beaches perhaps because of its small size and excellent tube camouflage. The little cone shaped tube is made of cemented sand grains (this is one great stone mason). At the open end can be seen a group of tentacle-like paleae that are used for digging through the sand. In addition there are short tentacles that are used to sort food item from the sand – detritus. The worm is oriented with the open end down in the bottom as it moves and feeds. The other end of the worm is anchored in the tube with numerous small hooks on the posterior end of the body. Reproduction: broadcast spawner, planktonic larvae.
Ribbon worms are predators feeding on other worms and small invertebrates. A few species are seen intertidally in Puget Sound. They can stretch to over two feet in length. Each uses a special harpoon-like structure to capture prey. Ribbon worms are not related closely to the annelid worms and show no obvious segmentation. Reproduction: sexes separate, larvae may be planktonic or benthic. Little is known of larval development in most species.
Bryozoans are small colonial animals that encrust much of the undersurface of intertidal rocks. Color or our local species is rust red. A close look with a magnifying lens will bring the tiny individual houses into view. Food is plankton and detritus captured with special tentacle groups called lophophores. Reproduction: Asexual by cloning but all individuals don’t necessarily look or act alike. Some may be reproductive, others defensive, others feeding or cleaning. Most bryozoans are separate sexes and broadcast spawners with planktonic non-feeding larvae. White bryozoans colonies are also often seen on kelp blades. Some very large (basketball size) colonies are found in local fresh water rivers.
Tunicates are invertebrates closely related to the Chordates – our phylum. They belong to the Urochordates or tailed chordates. They are all filter feeders on plankton. Water is pumped into the body through inhalant openings, food captured in a basket-like device and the water passed out the exhalant opening. Some form colonies and other live as single individuals. Larvae look like tiny tadpoles. The texture of colonies found on local beaches is like firm, wet rubber which is a good way to avoid confusing them with sponges or bryozoans. There are a number of local species of colonial tunicates and color is variable.
A rather uncommon solitary sea squirt in the low intertidal (most are subtidal). The tunic (tough outer covering) is somewhat clear and covered with sparse hairs. The inhalant and exhalant siphons are visible on the top. Reproduction: broadcast spawner, non-feeding planktonic larvae (tadpole larvae), separate sexes.
Another solitary sea squirt usually found subtidally but not uncommon at the low intertidal level and on pilings. Tunic is very wrinkled and warty looking. Clusters are often found together often attached to each other. Reproduction: May be a brooder or broadcast spawner or both...not completely understood. Food: Planktonic zooplankton.
The tomato soup color seen in Puget Sound waters during the summer months is the result of population explosions of single-celled dinoflagellates called Noctiluca. Noctiluca does not cause Paralytic Shellfish Poisoning. It is responsible for the glowing green color or breaking waves and boat wakes at night. Each individual produces flashes of bioluminescence. This is a chemically produced cold light. This may be a defense against predation by fish. As the fish swims through the noctiluca it creates a trail of light which can allow its visual predators to home in on the fish, thus reducing predation on noctiluca.
Plainfin midshipman: Often found under rocks where dens are located. Midshipmen look like sculpins but are not closely related to them. Males dig burrows under rocks and sing to females. Interested females enter the den and lay a few hundred large yellow eggs attached to the underside of the rock. The eggs are fertilized externally by the male. Some males look and act like females (even sound like them) and attempt to sneak into the den posing as females where they will attempt to fertilized the eggs before the den owner figures out the ruse. If chased out of the den by a wise den owner the female mimicking male will wait outside and try to push his sperm into the den with his tail during mating of the other pair. Midshipmen have razor-sharp gill covers and should not be handled.
Tidepool sculpins are common in intertidal pools. Color is variable and changes with the environment. They have an excellent homing instinct and larger individuals can find their way back to their home tidepool from a distance of at least 100 yards. It seem that homing is a learned talent and that younger fish spend time learning the neighborhood before selecting a home tidepool. Eggs are attached to rocks and look like clusters of tiny grapes. Color or the eggs is pale green. Most sculpins have sharp spines on the gill covers and can inflict painful puncture wounds. Food: small invertebrates, including limpets, shrimp, amphipods, barnacle cirri and other small fish. There are a number of other sculpin species in Puget Sound that are seen in tidepools including: Rosylip, Sharpnose and Scaleyhead. All three are similar in appearance and size making field identification problematical. Other larger sculpins are found in subtidally. There are over 30 species in local waters.
Sculpin eggs - species unknown
Other eel-like fish include the pricklebacks which are often found in the same habitat under intertidal rocks. All except the rock prickleback are predators on small invertebrates. The rock prickleback is a carnivore early in life but becomes a seaweed eater as an adult (one of the few vegetarians among Puget Sound fishes).
Gunnels are eel-like fish that are not true eels. They are commonly found under rocks in the low intertidal. They prey on small invertebrates. Color varies from green to yellow to red. Gunnels wrap themselves around their egg masses until they hatch. These belong to the same order as the wolf-eels. Penpoint gunnels are named for the single fin spine near the anus. The fish can be over a foot long though most found under rocks are smaller.
Gunnels protect their eggs under rocks.
There are some 20 + species of flatfish in Puget Sound. The largest being the halibut. Juveniles are sometimes seen intertidally in sandy tidepools. There are no TRUE sole (family Soleidae) in Puget Sound. Everything called a sole in this area is actually in one of 2 different families; the right-eyed flounders and the left-eyed flounder (sanddabs). Sanddabs (family Bothidae) are small flatfish that are left-eyed while most other flounder (family Pleuronectidae) are right-eyed and larger (includes halibut). The Starry Flounder are the exception being either right or left-eyed. The family Soleidae (soles) is not represented in our are but are closely related to the flounder. All fish in our area called “sole” are actually flounders. All of these species begin as planktonic larvae looking very much like a normal fish. While they are still quite small they undergo a wild transformation. One eye migrates to the opposite side of the head and the fish begins swimming on its side. The upper facing side now with both eyes. In addition the underside is unpigmented while the upper side becomes capable of rapid color change to match the bottom. The fish now take up a bottom dwelling lifestyle, often buried in the sand and very well camouflaged. Reproduction: Broadcast spawners, planktonic larvae. Food: small to large invertebrates and fishes depending on the species in question. The English sole in commonly seen in sandy tidepools.
Clingfish are small (up to 6 inches) intertidal fish that have fins, pectoral and sometimes pelvic, modified into a suction cup for attachment to the rocks. Food: a wide variety of small invertebrates and fish. Reproduction: females lay eggs (up to 400) attached in a single layer to the rock surface (underside of rock). Eggs are yellow and about BB size. Males guard the eggs, larvae are planktonic. In the San Juan Islands gopher snakes enter the intertidal and eat clingfish.
Green – found where freshwater streams or seeps enter the beach. Both fresh and salt water tolerant.
Green seaweed – can be extremely abundant on beaches in the summer months. In some areas it piles over a foot deep and can suffocate clams living beneath it. It also is food for a large number of invertebrates and some waterfowl.
Green seaweed – common on local beaches
Brown seaweed: High intertidal – very resistant to drying and can lose 80% of its moisture content and survive. Fattened ends of blades are reproductive areas. They release gametes that fuse, settle to the bottom and grow into another sexually reproductive adult. Life cycle is animal-like. Mats of rockweed are habitat for many species of juvenile invertebrates. The jelly-like substance in the reproductive areas makes a nice skin lotion.
Brown seaweed with sulfuric acid. Acid is released when the seaweed is stressed and will kill anything else you have in your collecting bucket.
Brown seaweed – common on local beaches in spring.
Brown seaweed – large with many floats
Brown kelp – low intertidal
Sargassum (Spanish for seaweed) – an introduced seaweed that covers large areas of the intertidal and shallow subtidal. It can be host of over 100 species of invertebrates but also may contribute to upsetting the ecological balance of seaweed on our beaches. It is highly prized as food by some Asian cultures.
Brown seaweed – high in sugars and food for many beach animals.
Brown kelp – very large – this is the spore forming stage – spores released from blades settle to bottom and develop into tiny over-wintering stage that reproduces sexually and give rise to the large summer phase. Only kelp that releases a spore PATCH.
Brown seaweed with strong mid-rib
Red seaweed – Rainbow or iridescent seaweed.
Red seaweed – the structure of the blade caused the reflected rainbow-like colors.
Red seaweed Also known as dead man’s fingers. There is also an flatten brown seaweed known as the sea chip.
Red seaweed – seen in large bunches. Small bunches are often seen even in winter.
Red seaweed – texture of towel
Red seaweed – encrusting phase of Turkish Washcloth seaweed
Red seaweed – forms hard crust – calcium carbonate in cell walls