When it’s low tide these creatures are quite conspicuous. They can be identified by several light colored plates that form the a cone that sits on top of a dark stalk.

These barnacles are typically found in large clumps and often in the midst of mussels. They can grow several inches long depending on the conditions. Gooseneck barnacles have a fleshy, muscular stalk reaching 4 to 6 inches in length with a calcareous tip.

Barnacles are filter-feeding crustaceans that live attached to hard surfaces of rocks and flotsam in the ocean intertidal zone. Barnacles filter-feed when the tide is high, using small feather like appendages called cirri to catch plankton.

Goose barnacles, like all barnacles, are exclusively marine invertebrates but, unlike many other members of their class, they are hermaphrodites, meaning that they have both male and female sexual organs.

Their eggs hatch into free-swimming larvae, which drift with the ocean currents as one of the immense number of animals that comprise zooplankton. Once they attach to the rocks as larvae, where they do not move from for their entire lives.

In folklore, Barnacle Geese were once held to emerge fully formed from Goose Barnacles. In culture, Barnacle Bill became a comic folk-type of a seaman, appearing in several films and a drinking song.

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While tidepooling in the San Francisco Area, I came across this cool creature. With a Scientific Name of Ashtoret lunaris, it is more active at night and is rarely seen in the daytime, as it is then often buried in the sediments. “Lunaris” in Latin refers to the moon.

The Spotted Moon Crab’s colors range from beige to yellow, with little maroon dots evenly sprinkled on the body surface, sometimes highlighting the six bumps. Its pincers are short, sturdy, held against the body to form a somewhat box-like shape. Its walking legs end in paddle-shaped tips and are used to skim along the sea bottom as well as being used like spades to rapidly burrow into the sand.

This crustacean is commonly encountered in sandy and muddy shores, especially near seagrass beds from the intertidal zone to a depth of 150 feet. It is usually nocturnal and spend the day buried in the substrate just below the surface, creating breathing channels to the surface of the sand.

They hunt small shellfish, worms and other animals. During the night, they are known to take other crabs. When threatened, it often draws its legs up under the overlapping edges of the carapace and appears to sham death; this may make it difficult for a predator to dismember the crab

I have caught several different types of cool crustaceans while out and about, but this was the first time I’ve ever come across this species.

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While walking along a canal in Japan, I found a few rocks to turn over. Under them were some isopods. With the Latin Name of Porcellio laevis, the species epithet laevis as well as the vernacular name “Swift Woodlouse” suggests, the species is capable of quick bursts of speed when provoked.

This type of woodlouse is distinctively large, being up to eight tenths of an inch long with a smooth dorsal surface. It is commonly kept as a pet due to its somewhat easy care requirements and the variety of color morphs available. “Dairy Cow Isopod” is a commonly used name for a readily available piebald strain of the species.

Baby Swift Woodlouse directly develop from yolky eggs. Both the eggs and juveniles reside within a brood pouch called a marsupium. The use of the marsupium eliminates the need for there to be an external water source for early development, since it is filled with fluid from the mother isopod. This is considered some of the most extensive parental care among terrestrial arthropods.

This creature is found under rocks and fallen logs in damp areas, and is otherwise rarely encountered. It plays an important role in nutrient cycling by breaking down dead plant material and animal waste, and thereby releasing essential nutrients back into the ecosystem. It is known to be an opportunistic feeder, consuming a wide range of organic matter such as leaves, moss, lichens, and even rotting wood. Therefore, it can thrive in many different ecological niches.

The Swift Woodlouse is one of several species of isopods known to use “alternating turns” as a defense mechanism, running in a mazelike pattern to confuse or avoid perceived threats. Studies suggest that this behavior can be reinforced as a learned response, with more “alternating turns” produced by longer and more frequent exposure to predators.

It was super cool to come across these fine crustaceans while on my international trip.

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Ghost Shrimp are relatively small invertebrates, reaching a maximum size of only two inches. Their see-through bodies and frenetic food-searching behavior make them fun to watch.

While the Ghost Shrimp’s body is transparent, an orange-to-yellow colored spot is often visible in the center of the tail. The body is segmented, and features ten sets of legs. The first four sets of legs have tiny claws that aid the shrimp in feeding.

This crustacean is naturally found in freshwater ponds, lakes, and streams in the coastal plain of North America east of the Allegheny Mountains, from Florida to New Jersey. They are most abundant in dense beds of submerged vegetation. This creature is considered a keystone species based on the services it provides to its habitat.

The diet of Ghost Shrimp is dominated by algae, though they are scavengers and consume a wide variety of tiny food items. It is nocturnal, remaining hidden among the vegetation by day, and emerging at night to feed. It is an important prey item for a number of birds and fish.

They are common aquarium pet due to their unique appearance – they also known as Jumpers, Glass Shrimp, Grass Shrimp, Glass Prawns, Hardbacks, Daggerblades and Popcorn Shrimp.

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Often when I look in a tidepool I see nothing of interest. By if I stare into the water long enough, I’ll start to see small creatures reveal themselves by their movements. Most of these inhabitants are well-camoflauged and only their activities give them away. A great example of this is the Marine Hermit Crab.

There are over 500 species of hermit crabs around the world, and they’ve evolved a unique body shape to fit into their shell homes. Unlike free-living crabs, their abdomens aren’t covered in a hard exoskeleton but rather a thin, soft one; their abdomens are also twisted to fit the spiral cavity of the snail shells in which they make their homes. Some species live mostly on land, while others rarely leave the water.

Like all crabs, the Marine Hermit Crab is a decapod — it has five pairs of legs, including a pair of claws. It uses its claws for defense and food shredding as well as eating. The second and third pairs of legs help the crab walk, and the last two pairs hold the crab in its shell.

Hermit Crabs are pretty easygoing about what they eat. In fact, they’ll dine on just about anything they can find in the water that surrounds them – including small fish, invertebrates such as worms, plankton and any food particles that happen to be floating by.

Hermit Crabs don’t kill the snails in whose shells they make their homes. They’re actually able to smell dead or dying snails, which can lead them to a potential shell. But competition for such shells can be fierce. They may fight to the death in pursuit of a shell. And, as they grow, they must seek out new shells in which to live.

Contrary to their name, hermit crabs live very social lives. They live in big groups, travel together and even meet up to search for food and shells.

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I have found this brightly colored crustacean while visiting both southern Nevada and southern California.

The Lousiana Swamp Crayfish is found in rivers, bayous, swamps, ditches, ponds, lakes, and rice fields throughout the southcentral United States and northeastern Mexico. It seems to prefer flooded wetland habitats with periodically flowing, well-oxygenated water. This species retreats into burrows when surface water dries up.

This creature is a physical ecosystem engineer, constructing burrows consisting of a single opening, which may be covered with a mud plug or raised above ground level in the form of a chimney to reduce evaporative loss further from the water’s edge. The opening leads to a tunnel which widens to an enlarged chamber at the end.

Crayfish are opportunistic omnivores. They can detect small amounts of blood and decomposition scents in the water to track down and feed on partially decomposed plant material, living soft plants, and virtually any type of animal matter.

The Lousiana Swamp Crayfish is a very successful invasive species. Not only can it be found in many parts of the United States where it is not native, but can also be found in inland waters on all continents except Australia and Antarctica. In the United States it is readily available though the biological supply trade and specimens and is sometimes released following classroom or laboratory use. It is also popular among anglers as bait for Largemouth Bass.

Part of the reason it is now found in other countries is importation for crayfish farming. Eating freshwater crayfish is common in many countries. The first known introductions of this species took place in the 1920s: 1924 in California and 1927 in the Hawaiian Islands, 1927 in Japan, and 1929 in China. In the mid-1960s, a batch of crayfish was sent to Uganda and Kenya, and soon afterwards, to other African countries.

The life cycle of the Louisiana Swamp Crayfish is relatively short, with an onset of sexual maturity occurring in as few as two months and a total generation time of four and a half months. Although they look attractive (for a crustacean), this species competes aggressively with native crayfish species for food and habitat.

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I found this cool creature while tidepooling on the California Coast. Crabs come in many shapes and sizes, but they have a few things in common – usually ten jointed legs and eyes at the ends of short stalks.

The Purple Shore Crab can be found sheltering under rocks in inter-tidal areas along the west coast of North America. They are quite adaptable, being found from the frigid shores of Alaska all the way to the sunny beaches of Baja California.

These crustaceans look for food during low tide at night on top of rocks and on nearby sandy beaches. They feed on green algae, snail eggs, smaller animals and more. On the flip side, for their part, they’re eaten by scoters (a type of sea duck), fish and gulls.

Purple Shore Crabs are rarely found in water deeper than three feet. They prefer rocky coastlines where hiding places are plentiful, because they do not burrow in sand, like many other crabs.

They have the ability to regulate the amount of salt in their systems, a trait called osmoregulation. This enables them to live rather far into brackish estuaries and salt marshes, where the the level of salt in the water changes with the tides.

The mating ritual of purple shore crabs involves a bizarre dance during which males and females rise up and embrace, belly to belly. The males clasp females firmly with their legs and claws, and fall over backwards.

The Purple Shore Crab truly was a fun find on my California trip.

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While tidepooling on the Pacific Coast, we found a few of these cool and colorful creatures.

The Stout Shrimp is one of several species of shrimp with the common name “Broken Back” Shrimp, named for the sharp angle of the attachment of its tail to its body.

This crustacean’s color is highly variable, ranging from white mottling or stripes to browns and greens. It regularly occurs in the intertidal zone or along the sides of floats, where they are often the most commonly seen shrimp.

The Stout Shrimp is nocturnal and comes out at night to forage for food. During the day they can be found under seaweed, hidden around rocks or nestled among mussels.

It is mainly carnivorous, feeding on a variety of small animals. In turn, it is eaten by a variety of fish…but only if the fish can catch them. Like crayfish, these shrimp use the rapid flexing of their tail to scoot away from danger.

Although small, these fine invertebrates were a fun find while exploring California.

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While visiting Point Reyes National Seashore in California, I hiked along small waterways in a cattle grazing area and saw a number of these neat crustaceans.

Typically this crab is brown-to-purple or black with green stripes. Though this color combination makes it eye-catching when seen out in the open, it also helps the crab disappear into dark, rocky crevices where it hides in sea lettuce, rock weed and bits of kelp.

Although there can be aggressive intraspecies competition over food, this creature does not keep a territory to defend. It can spend over half of its time on land and will purposely submerge to wet its gills; it can sustain itself out of water for up to 70 hours.

Striped Shore Crabs live along the West Coast of North America, from Mexico in the south, to Vancouver Island, Canada, in the north. In additional to cattle grazing fields, they reside in estuaries, tidepools, mussel beds and in the burrows they sometimes dig into sandy banks. They can sometimes be seen scuttling along shoreline rocks.

The variety of habitats where they exist mirrors the variety of foods they’ll eat. Though they feed mostly on phytoplankton growing on the water or rocks around them, they are opportunistic and will also eat animals including dead fish, limpets, snails, isopods, worms and mussels.

Striped Shore Crabs were an unexpected and fun find while on my visit to the Golden State.

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We found several of these super cool crustaceans while tidepooling in California. Like other members in their family, they have very tough exoskeletons to protect them from predators.

These crabs belong to a large group called “Spider Crabs.” They generally have long legs with relatively small body. Their carapace (back shell) somewhat resembles a five-pointed sheriff’s badge; it is smooth and is longer than it is wide.

This species is usually dark brown. Kelp Crabs, as their name implies, are typically associated with their namesake plant and they are colored much like kelp. Their legs end in sharp points, which are used to cling to slippery surfaces.

These creatures are herbivores most of the time. During the Summer they nip off bits of brown algae such as kelp, rockweed and sea cabbage, as well as several types of red algae. When the algae die back during Winter, they turn to an animal diet, including small mussels and barnacles.

Kelp Crabs are found in rocky intertidal areas, kelp beds and around structures such as pier pilings. In the Fall, adults move to deeper water where they congregate, feed and mate. They use kelp beds not only for food, but also as shelter against predators such as Sea Otters.

These creatures will sometimes attach pieces of kelp to the points on their carapace, saving them to eat later. While these long-legged invertebrates look delicate, they are stronger than you may think and are able to give forceful pinches with their front claws.

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