Invertebrate Species found on BHI

Blue Crab


Click below to learn more about the different species of invertebrates found on Bald Head Island

Atlantic Ghost Crab

Atlantic Ghost Crab, Ocypode quadrata


Identification: Mature ghost crabs are tan with white claws, while immature crabs are usually a darker gray. Males are typically larger than females, and their carapace can grow up to three inches. They have ten legs total and distinctive eyestalks sticking up from their heads.
 
Habitat and Habits: Ghost crabs live in the sand of coastal beaches in both North and South America. Living on the beach year round, ghost crabs dig burrows where they escape the sun in summer and hibernate in winter. They are primarily nocturnal omnivores and will eat filter-feeders, loggerhead sea turtle hatchlings, and vegetation.
 
Conservation: Not Evaluated.
 
Ghost crabs are not thought to be threatened or endangered, but their population can be affected by off-road vehicles driven on the beach, coastal erosion, and beach development.
 
Cool Facts:

  • Ghost crab burrows can be up to four feet deep.
  • Ghost crabs’ eyestalks can rotate a full 360 degrees.
  • Specialized hairs on their legs extract water from damp sand to wet their gills.

 
On BHI:  Ghost crabs can be found on the beaches of Bald Head, especially at night. Join a Bald Head After Dark or a Turtle Walk for a chance to see one!

Atlantic Purple Sea Urchin

Atlantic Purple Sea Urchin, Arbacia punctulata


Identification: Atlantic purple sea urchins can be identified by the long purple spines that encircle their bodies. Their bodies are called tests and can grow to between one and two inches. Sea urchins also have a unique feeding structure called Aristotle’s lantern, which is composed of five teeth that form a beak-like mouth.
 
Habitat and Habits:  Atlantic purple sea urchins can be found on most of the North American Atlantic coast. They prefer to live on rocks at depths of up to 750 feet, but can occasionally be found close to the low-tide line.  Sea urchins move using an internal vascular water system and consume algae and other small organisms in the ocean water.
 
Conservation:  Not Evaluated.
 
Because of their relatively secluded habitat, the largest threat facing Atlantic purple sea urchins is ocean pollution.
 
Cool Facts:

  • Sea urchins can regrow their spines when they break.
  • Sea urchin spines serve as habitats for small ocean organisms.
  • The sea urchin got its name from old English where it means ‘spiny hedgehog’.

 
On BHI: While rare, sea urchins can sometimes be found washed up in tidal pools on the beaches of Bald Head. Learn about them at the BHI Conservancy’s Touch Tank Time
   

Blue Crab

Blue Crab, Callinectes sapidus


Identification: Blue crabs are most identifiable by the shades of blue apparent on their arms and legs.  Males can grow up to eight inches in size, while females tend to be smaller and have red-tipped claws.  Both sexes have an olive-colored shell and five pairs of legs, the last of which are flat and function as paddles.
 
Habitat and Habits: Blue crabs are abundant along the eastern seaboard from as far north as Nova Scotia all the way south to the Gulf of Mexico.  They are scavengers, known to eat other crustaceans as well as decaying plant and animal material.  Blue crabs usually live between one and three years, mating between the months of May and October.
 
Conservation: Not Evaluated.
 
Threats to the species include habitat loss and fragmentation.
 
Cool Facts:

  • Translated to English,“Callinectes sapidus” means beautiful, savory swimmer.
  • Blue crabs are one of the most heavily harvested species in the world.
  • Female blue crabs lay up to two million eggs in sponge-like masses.

 
On BHI: Blue crabs can be found in the marsh near the public creek access, as well as in the ocean. Try to catch one during the BHI Conservancy’s Crabbing and Cast-netting program.

Cannonball Jellyfish

Cannonball Jellyfish, Stomolophus meleagris


Identification: Cannonball jellyfish grow to an average size of five inches long by seven inches wide. Coloration can vary, but all cannonball jellies have a characteristic, mushroom-like shape. Near the bottom of the jellyfish are sixteen arms that help it to feed.
 
Habitat and Habits: Cannonball jellyfish inhabit most coastal waters of the U.S., as they are native to both the Atlantic and Pacific Oceans. They live close to the shore where they feed on larvae and eggs of fish and mollusks. Cannonball jellyfish have short lifespans (between three and six months, on average) because they are often eaten by predators, but they can secrete a toxic mucous in an attempt to avoid being eaten.
 
Conservation: Not Evaluated.
 
Cannonball jellies, like most marine species, can be affected by climate change and pollution. They play numerous important ecological roles including being a main prey species of the leatherback sea turtle.
 
Cool Facts:

  • Cannonball jellies can weigh up to three pounds.
  • The cannonball jellyfish is the most common jellyfish in the southeastern US.
  • Their scientific name Stomolophus meleagris means ‘many-mouthed hunter’.

 
On BHI: Cannonball jellyfish can be seen washed up on the beaches of Bald Head, especially in the spring. Learn about marine invertebrates at BHI Conservancy’s Touch Tank Time.
   

Channeled Whelk

Channeled Whelk, Busycotypus canaliculatus


Identification: Channeled whelks can grow to between five and eight inches long and have the characteristic pear-shaped shell. They can range in color from tan to gray and unlike lightning and knobbed whelks, the spire (tip) of their shell is relatively smooth. A deep channel can also be found between the whorls (different layers) of the spire.
 
Habitat and Habits: Channeled whelks can be found on the east coast of the U.S., from Massachusetts to Florida. They are most often located in shallow waters and tidal pools where they have easy access to their prey - shallowly buried clams. Females lay eggs in casings that, when fertilized, are attached to the sand of the ocean floor until they hatch.
 
Conservation: Not Evaluated.
 
One major threat to whelks is climate change. As the concentration of CO2 increases in the atmosphere, it is absorbed by the ocean, making it more acidic. As CO2 binds to the hydrogen atoms in water molecules, it decreases the amount of available atoms that whelks require to grow and add to their shell.
 
Cool Facts:

  • Channeled whelks’ egg strings can be up to three feet long.
  • Channeled whelks are nocturnal, consuming most of their prey at night.
  • Whelks can sense where clams are located by following their water expulsions.

 
On BHI:  Channeled whelks and their shells can be found on the beaches of Bald Head Island, and you can see some up close at the BHI Conservancy’s Touch Tank Time.
 

Coquina Clam

Coquina Clam, Donax variabilis


Identification:  Coquina clams can be identified by their relatively small, triangular shaped shells.  Their colors are extremely variable and can range across the entire color spectrum.  At their largest, coquina clams can grow to about one inch long.
 
Habitat and Habits:  Coquina clams can be found (usually in colonies) along the North American east coast, as far north as New York and as far south as Texas. They prefer shallow waters or the sandy part of the beach where the tide ebbs and flows. Coquina clams are filter feeders and move through the sand using their muscular foot.
 
Conservation:  Not Evaluated.
 
Coquina clams are not thought to be threatened or endangered, but could face challenges posed by beach erosion and climate change, which can both affect their habitat.
 
Cool Facts:

  • They can only survive for three days without the presence of moving water.
  • Coquina clams are a vital food source for shorebirds and several species of fish.
  • As an indicator species, they signal changes in the environment by their aboundance. 

 
On BHI: Look for coquina clams on the beaches of Bald Head Island in the sand near crashing waves. Learn about marine invertebrates at BHI Conservancy’s Touch Tank Time.

Eastern Oyster or American Oyster

Eastern Oyster or American Oyster, Crassostrea virginica


Identification: Eastern oysters can grow to sizes between three and eight inches. Their shells range in color from white to tan to black, but can be identified from their unique shapes. An oyster’s top shell is flat while its bottom shell is curved, providing a space for the oyster to live. The bottom shell might also have a purplish dot called the muscle scar, where the living organism attaches to the shell.
 
Habitat and Habits: Eastern oysters can be found nearly anywhere along the eastern North American seaboard. They live in salty or brackish water and feed on food particles floating in the water. Most often oysters are found in beds or colonies close to many other oysters. They reproduce using a mass spawning strategy when waters warm to an appropriate temperature.
 
Conservation: Not Evaluated.
 
Oysters are generally successful in reproduction, but populations are heavily dependent on water quality. While eastern oysters feed by filtering organic pollutants from water, they can also ingest any chemical pollutants, which can lead to their death.
 
Cool Facts

  • Eastern oysters can live up to twenty years.
  • Eastern oysters can filter up to two gallons of water per hour.
  • Female eastern oysters can produce up to 100 million eggs each year.

 
On BHI: Eastern oysters are a prominent species in the marsh and can be seen on the BHI Conservancy’s Low-Tide Kayaking. Their shells can also be found on the beaches of BHI.

Atlantic Marsh Fiddler Crab

Atlantic Marsh Fiddler Crab, Uca pugnax


Identification: Fiddler crabs are small; their carapace can grow to be about one inch long. They are usually olive-brown in color. Males possess a distinctive large, white claw while females have pincers of the same size on both sides of their body.
 
Habitat and Habits: Atlantic marsh fiddler crabs inhabit salt marshes along the eastern seaboard. They burrow up to three feet into the ground, making small holes visible on the marsh surface. These tunnels have multiple uses, including protection from predators, reproduction, and hibernation during the winter months. They consume detritus and live to be about one year old.
 
Conservation: Not evaluated.
 
While it is thought that the current fiddler crab population is strong, habitat loss and degradation are two threats that could affect their population in the future.
 
Cool Facts:

  • They have four pairs of legs used for walking.
  • Fiddler crabs’ burrows help aerate vegetation growing in the marsh.
  • Fiddler crabs use their claw for mating, not for protection from predators.

 
On BHI: The Kent Mitchell trail is a great place to see fiddler crabs. Join BHI Conservancy for an Island Nature Tour to see a fiddler crab up close.

Forbes Sea Star

Forbes Sea Star, Asterias forbesi


Identification: Forbes sea stars grow between three and six inches in diameter, on average. They often have red, pink, or orange tones, and are echinoderms, meaning that they have spiny skin and five-way radial symmetry (the shape of a star). They also have an orange dot on their dorsal side called the madreporite.
 
Habitat and Habits: Forbes sea stars can be found on most of the Atlantic Coast in places where sunlight reaches the bottom of the ocean. They move using a water vascular system; water is taken in and ejected through the madreporite, allowing the sea star to move at a speed of about six inches per minute. Sea stars are carnivorous and reproduce by spawning.
 
Conservation: Not evaluated.
 
It is currently believed that the population of Forbes sea stars is doing fine. They have few natural predators because of their spiny skin and lack of nutrients, but can be threatened by human influences like habitat degradation or pollution.
 
Cool Facts:

  • Sea stars can regenerate as long as they have one arm and one-fifth of their inner disk.
  • Forbes sea stars largely use chemoreception to navigate the ocean floor.
  • Female Forbes sea stars can release up to 2.5 million eggs.

 
On BHI: Look for sea stars in tidal pools or other shallow parts of the ocean on the island. Learn about marine invertebrates at BHI Conservancy’s Touch Tank Time.

Ghost Shrimp

Ghost Shrimp, Palaemonetes paludosus


Identification: Ghost shrimp are transparent and can grow to about 1.5 inches in length. They have segmented bodies with ten pairs of legs and contain a yellow or orange spot in the middle of their bodies.
 
Habitat and Habits: Ghost shrimp can be found in freshwater and brackish water habitats where vegetation is prominent. Their natural range includes the states between New Jersey and Florida that are east of the Appalachian Mountains. Ghost shrimp primarily consume algae and can live up to two years. They are most active at night to decrease their risk of depredation.
 
Conservation: Not evaluated.
 
Threats to this species are limited. Ghost shrimp do well in warm waters, but may be impacted by pollution and habitat loss.
 
Cool Facts:

  • In warm waters they can be so active that they attack fish.
  • Female ghost shrimp can carry their eggs for up to two months.
  • They play a critical role in maintaining energy flow in their ecosystem.

 
On BHI:  Ghost shrimp can be found in most of the aquatic habitats on Bald Head. The Conservancy frequently house many invertebrates in the Barrier Island Study Center tanks.  Learn about marine invertebrates at BHI Conservancy’s Touch Tank Time

Atlantic Horseshoe Crab

Atlantic Horseshoe Crab, Limulus polyphemus


Identification: Horseshoe crabs are dark brown in color and have the appearance of a horse’s hoof. Females are larger than males, and can grow to nineteen inches. Horseshoe crabs have segmented bodies with a distinct head, torso, and tail.
 
Habitat and Habits: The Atlantic horseshoe crab can be found anywhere along the eastern North American coast. They usually inhabit waters under 100 meters in depth. Horseshoe crabs are scavengers, feeding on anything they can find on the ocean floor. To mate, females crawl onto a beach and begin digging a hole for eggs while males attach to females and begin releasing sperm to fertilize the eggs.
 
Conservation: Vulnerable.
 
Horseshoe crabs are harvested for bait and biomedical purposes, and are also threatened by bycatch, habitat loss, and coastal development. Some states have implemented management plans to help the horseshoe crab population regain some of its numbers.
 
Cool Facts:

  • Females can lay up to 80,000 eggs in one spawning season.
  • Their blood can be used to detect gram-negative bacteria in medical devices.
  • Horseshoe crabs are more closely related to spiders and scorpions than to crabs.

 
On BHI: Look for horseshoe crabs on the beaches of Bald Head Island, or check out the BHI Conservancy’s wet lab to see some horseshoe crab molts. Learn about marine invertebrates at BHI Conservancy’s Touch Tank Time

Knobbed Whelk

Knobbed Whelk, Busycon carica


Identification: Knobbed whelks range in size from five to nine inches long. They have short, pointed projections on the shoulder of their shell, and when held up straight with the shell opening visible, open to the right. The shell can vary in color with some whelks being white, some tan, and some grey or black.
 
Habitat and Habits: Knobbed whelks are most commonly found in shallow ocean waters and tidal pools, but have been recorded living in the ocean at depths of 150 feet. They can be found on most of the eastern coast of the U.S. Knobbed whelks are carnivorous, consuming bivalves by prying them open with the long, straight part of their shell. Females lay eggs in casings that, when fertilized, are attached to the sand of the ocean floor until they hatch.
 
Conservation: Not evaluated.
 
One major threat to whelks is climate change. As the concentration of CO2 increases in the atmosphere, it is absorbed by the ocean, making it more acidic. As CO2 binds to the hydrogen atoms in water molecules, it decreases the amount of available atoms that whelks require to grow by adding to their shell.
 
Cool Facts:

  • Knobbed whelks are born with a shell about ⅛ inch long.
  • Whelk eggs can take up to thirteen months to develop and hatch.
  • Knobbed whelks are all born as males and turn to females as they age. 

 
On BHI:  Be on the lookout for whelks when you’re on the beach, or check out the BHI Conservancy’s Touch Tank Time to see some up close.

Lightning Whelk

Lightning Whelk, Busycon perversum


Identification: Lightning whelks usually have white or tan shells and can grow up to sixteen inches in size. Their shells have distinctive “lightning strikes” moving down the sides, and their bodies are brown or black. Lightning whelks can be referred to as left-handed whelks because their shell opens on the left side. This feature can be used to distinguish lightning whelks from the similar looking knobbed whelks.
 
Habitat and Habits: Lightning whelks can be found on the east coast of the U.S., from New Jersey to Texas. They inhabit relatively shallow waters and are carnivorous, consuming various types of bivalves. Their eggs are laid in strings that can be up to three feet long and are attached to the ocean floor where they will eventually hatch.
 
Conservation:  Not evaluated.
 
One major threat to whelks is climate change. As the concentration of CO2 increases in the atmosphere, it is absorbed by the ocean, making it more acidic. As CO2 binds to the hydrogen atoms in water molecules, it decreases the amount of available atoms that whelks require to grow and add to their shell.
 
Cool Facts:

  • Lightning whelks were collected by Native Americans for religious purposes.
  • Baby whelks begin their life by eating the eggs that did not hatch in their egg case.
  • Females achieve genetic variation in their young by mating with many males at once.

 
On BHI: Be on the lookout for whelks when you’re on the beach, or check out the BHI Conservancy’s Touch Tank Time to see some up close.
   

Eastern Mud Snail

Eastern Mud Snail, Ilyanassa obsoleta


Identification: Eastern mud snails are small, only growing to about one inch long. They have a dark brown or black shell with only a few whorls that resembles the shape of an oval.
 
Habitat and Habits: Mud snails can be found in their native range along the eastern coastline of North America. They are common inhabitants of salt marshes where they can often be seen in large colonies. Mud snails are scavengers, eating the decaying organic material in mud using their siphon. They deposit their young into the water where they will develop into mud snails that can live up to five years.
 
Conservation: Not Evaluated.
 
The population of eastern mud snails appears to be strong, and the species is invasive on the western coast of the U.S.
 
Cool Facts:

  • Eastern mud snails are sometimes kept in aquatic tanks to keep them clean.
  • They grow almost entirely during the summer season; in winter they rarely grow at all.
  • Mud snails know to come together and reproduce through the use of chemo-reception.

 
On BHI: Look for mud snails at the public creek access. They can be seen when kayaking or crabbing in the marsh, and you can learn about them during the BHI Conservancy’s Touch Tank Time.

Marsh Periwinkle Snail

Marsh Periwinkle Snail,  Littorina irrorata


Identification:
Marsh periwinkle snails can grow to about one inch in size. They have white, gray, or tan shells that feature a prominent and textured swirl pattern. Similar to mud snails, the shape of the shell also resembles an oval.
 
Habitat and Habits: Marsh periwinkles can be found in salt marshes and estuaries along the eastern coast of the U.S., from New York to Texas. They are often seen on cordgrass or needlerush within marshes, scavenging for algae or decaying plant matter to eat. Living for up to five years, periwinkles spend most of their time on vegetation and are an important food species for many marsh organisms.
 
Conservation: Not Evaluated.
 
The population of marsh periwinkles appears strong, but continued habitat loss of salt marshes could threaten this species.
 
Cool Facts:

  • Periwinkles try to avoid predators by climbing up their stalks of grass.
  • Up to 2,600 marsh periwinkles can be found in one square meter of marsh grass.
  • Marsh periwinkles obtain oxygen by filtering water on grass blades through their gills.

 
On BHI: Marsh periwinkles can be seen in the marsh by walking on the Kent Mitchell Trail. Join BHI Conservancy for an Island Nature Tour to see one up close.
 

Purple Marsh Crab

Purple Marsh Crab, Sesarma reticulatum


Identification: The purple marsh crab can vary in color from olive green to a purplish-brown. It has ten legs and a square shell with a notch between its eyes that can grow to be one inch across.
 
Habitat and Habits: Purple marsh crabs can be found in salt marshes along the east coast, from Massachusetts to Florida. They are most active at night when they emerge from their dens to feed on marsh grasses and occasionally other crabs (like fiddler crabs). When left unchecked, they have been known to decimate marsh cordgrass populations, leaving unstable mud in their wake.
 
Conservation: Not evaluated.
 
Marsh crab populations are thought to be strong, but habitat loss of salt marshes could threaten this species.
 
Cool Facts:

  • Female marsh crabs can carry up to 13,000 eggs at one time.
  • Burrows can be up to thirty inches deep and are often interconnected.
  • Males can produce a “rapping” sound when protecting their burrows from other crabs.

 
On BHI: Purple marsh crabs are commonly seen in the salt marsh, either at the public creek access or on the Kent Mitchell Trail. Join BHI Conservancy for Bald Head After Dark to see some at night!

Portly Spider Crab

Portly Spider Crab,  Libinia emarginata


Identification: Portly spider crabs are medium brown in color and have triangular-shaped shells that can grow to about four inches. In the middle of the shell are nine spines that project upward and often catch debris, which can give the shell a disheveled appearance. They have ten legs with tapered white claws at their ends.
 
Habitat and Habits: Portly spider crabs are found on the ocean floor and the bottoms of other bodies of saltwater. They can be found along the entire eastern North American coast, up to depths of 150 feet. Although their eyesight is poor, spider crabs can use their legs to sense movement and to taste in their search for food, which is primarily sea stars.
 
Conservation: Not Evaluated.
 
Not much information is known about spider crab population or potential threats that could affect them in the future.
 
Cool Facts:

  • Unlike most crabs that walk sideways, portly spider crabs walk forward.
  • When their legs are fully outstretched, these crabs can be one foot long.
  • Spider crabs can inhabit waters low in oxygen or even waters that have been polluted.

 
On BHI: Check tidal pools on the beach or look on the ocean floor for a chance to see a portly spider crab. Learn more about marine invertebrates at BHI Conservancy’s Touch Tank Time.

Quahog Clam

Quahog Clam, Mercenaria mercernaria


Identification: Quahog clams, also known as hardshell clams, range in color from white to gray. They can grow up to four inches long and have a distinctive lined structure on their shell where dark rings are also visible.
 
Habitat and Habits: Quahog clams can be found in the intertidal regions of the entire North American east coast. They burrow in the sand to avoid washing up on the beach and filter feed using their two siphons. They move around using a muscular foot and can tolerate and even consume some pollutants in their environment. Their average lifespan is between four and eight years.
 
Conservation: Not Evaluated.
 
Since quahog clams are a popular food for humans, overfishing could become a threat to this species. High levels of pollutants could also cause major declines in their populations.
 
Cool Facts:

  • Large quahogs can filter up to a gallon of water per hour.
  • All of the quahog clam body is edible unlike other larger clams.
  • Quahog clam shells were used as currency by Native Americans. 


On BHI:
Look for quahog clams on the beach or during a Low-Tide Kayaking trip. Learn more about marine invertebrates at BHI Conservancy’s Touch Tank Time.


 

Sea Squirt

Sea Squirt, Molgula manhattensis


Identification: Sea squirts, as known as sea grapes, are round invertebrates with two siphons on one end of their body. They can grow to two inches big and are usually a pale yellow color. Their bodies are tough and have a leathery texture.
 
Habitat and Habits: Sea squirt live on hard, permanent structures found in fairly shallow waters, including docks and jetties. They are native to the east and gulf coasts of North America and are filter feeders. Water and particles of food enter through one siphon and wastes are ejected through the other.
 
Conservation: Not Evaluated.
 
Sea squirts have been introduced to the west coast of North America, as well as to Europe, Australia, and Japan, where it is an invasive species.
 
Cool Facts:

  • They can live in heavily polluted waters.
  • Larvae are born with a nerve cord, which is absorbed into the body within days.
  • Sea squirts will eject the water in their bodies when squeezed or otherwise disturbed.

 
On BHI: Sea squirts can be found on the submerged portion of docks in the marsh. Sign up for Marsh Fishing or Crabbing and Cast-netting for a chance to find some.

Thinstripe Hermit Crab

Thinstripe Hermit Crab, Clibanarius vittatus


Identification: Hermit crabs can be found in various types of shells, but thinstripe hermit crabs have unique  bodily characteristics that can help in their identification. They have two legs with claws of equal size, and a thin white strip can be seen on all of their legs. Body color can range from gray to green.
 
Habitat and Habits: In North America, thinstripe hermit crabs can be found on the east coast in any location south of Virginia. They inhabit shallow bodies of saltwater, like the intertidal region of the Atlantic and edges of salt marshes and lagoons. Thinstripe hermit crabs can eat nearly anything and will change shells as they grow, living in shells exceeding four inches in length.
 
Conservation: Not Evaluated.
 
Since hermit crab shells are made of calcium carbonate significant increases in ocean acidification could damage their shells.
 
Cool Facts:

  • Thinstripe hermit crabs are the largest species of hermit crabs.
  • Water moving through its gills creates a ‘snap, crackle, pop’ sound when on land.
  • Females can lay up to 180,000 eggs per year, which are released in a spongy mass.

 
On BHI:  Search for thinstripe hermit crabs on west beach or attend BHI Conservancy’s Touch Tank Time to learn more about this species .