Invertebrates
An invertebrate is an organism that does not have a backbone. These animals rely on other strategies for support, such as hydrostatic pressure, exoskeletons, or shells. Over 98% of the species on Earth are invertebrates.
Marine invertebrates are invertebrate organisms that have made their homes in the ocean. This includes several different phyla of organisms, including:
Phylum Mollusca: Clams, Mussels, Whelks, and Squid.
Phylum Arthropoda: Horseshoe Crab, Lobster.
Phylum Echinoderma: Sea Stars, Sand Dollar.
Marine invertebrates are invertebrate organisms that have made their homes in the ocean. This includes several different phyla of organisms, including:
Phylum Mollusca: Clams, Mussels, Whelks, and Squid.
Phylum Arthropoda: Horseshoe Crab, Lobster.
Phylum Echinoderma: Sea Stars, Sand Dollar.
Atlantic surf clam
Scientific Name: Spinsula Solidissima
Appearance: The surf clam is a fairly large clam that can grow to be around 8 inches long. They have a yellow-white to grayish outer shell and a white to cream colored interior. The shell is think and oval or somewhat triangular. The shell is smooth except for concentric growth lines.
Diet: Clams have a diet of microscopic plankton. They have a “neck” composed of two siphons that allow water containing these organisms into their mantle cavity.
Location: These clams can be found all over the Eastern coast, from Nova Scotia down to the Carolinas. They live in very low intertidal zones or sub-tidally along beaches. They burrow down into the sand or mud at depth between a few inches or more than 100 feet.
These clams are edible for humans. They are often sold caned or used in clam cakes.
Appearance: The surf clam is a fairly large clam that can grow to be around 8 inches long. They have a yellow-white to grayish outer shell and a white to cream colored interior. The shell is think and oval or somewhat triangular. The shell is smooth except for concentric growth lines.
Diet: Clams have a diet of microscopic plankton. They have a “neck” composed of two siphons that allow water containing these organisms into their mantle cavity.
Location: These clams can be found all over the Eastern coast, from Nova Scotia down to the Carolinas. They live in very low intertidal zones or sub-tidally along beaches. They burrow down into the sand or mud at depth between a few inches or more than 100 feet.
These clams are edible for humans. They are often sold caned or used in clam cakes.
Blue mussel
Scientific Name: Mytilus edulis
Appearance: The blue mussel has a violet-blue shell with a black covering. Their somewhat thin shells are fan or tear shaped. The interior of the shell is bluish white. Its top margin is bluntly angled and the bottom margin is fairly straight. The hind end is rounded.
Diet: Blue mussels eat small phytoplankton. Like clams, blue mussels siphon in seawater full of plankton, which is then filtered through their gills.
Location: These mussels are can be found of both North American coasts, as well as Europe and South America. On the east North American coast, they can be found from the Arctic to South Carolina. These mussels attach themselves to rocks or wooden structures near the low-tide line.
These mussels are often called the “common edible mussel”. There are several aquaculturists in Maine that raise them.
Appearance: The blue mussel has a violet-blue shell with a black covering. Their somewhat thin shells are fan or tear shaped. The interior of the shell is bluish white. Its top margin is bluntly angled and the bottom margin is fairly straight. The hind end is rounded.
Diet: Blue mussels eat small phytoplankton. Like clams, blue mussels siphon in seawater full of plankton, which is then filtered through their gills.
Location: These mussels are can be found of both North American coasts, as well as Europe and South America. On the east North American coast, they can be found from the Arctic to South Carolina. These mussels attach themselves to rocks or wooden structures near the low-tide line.
These mussels are often called the “common edible mussel”. There are several aquaculturists in Maine that raise them.
Short-finned squid
Scientific Name: Illex illecebrosus
Appearance: Short-finned squid are sleek and torpedo-shaped. These squid have two long, retractable tentacles and eight shorter arms. They have large eyes and good vision. Not including their arms and tentacles, their mantle (body) is around a foot long at maximum. Females are generally larger than males. Their fins are short, only about a third of the length of their mantle.
Diet: Short-finned squid prey upon small fish and krill. They use their two tentacles and eight arms to latch onto prey and transfer it to their beak. They eat small crustaceans when they are small and eventually move up to fish, such as herring, when they grow.
Location: These squid live all along the North American Atlantic coast, from Newfoundland to Florida. When they are young, they live in the Gulf Stream. As they grow they more onto the continental shelf and then inshore waters.
These squid only have a lifespan of one year. Their entire purpose is to reproduce and they die after spawning. Shortfin squid still play a vital part in the oceans food chain, as they are a favored prey of many types of fish and marine mammals.
Appearance: Short-finned squid are sleek and torpedo-shaped. These squid have two long, retractable tentacles and eight shorter arms. They have large eyes and good vision. Not including their arms and tentacles, their mantle (body) is around a foot long at maximum. Females are generally larger than males. Their fins are short, only about a third of the length of their mantle.
Diet: Short-finned squid prey upon small fish and krill. They use their two tentacles and eight arms to latch onto prey and transfer it to their beak. They eat small crustaceans when they are small and eventually move up to fish, such as herring, when they grow.
Location: These squid live all along the North American Atlantic coast, from Newfoundland to Florida. When they are young, they live in the Gulf Stream. As they grow they more onto the continental shelf and then inshore waters.
These squid only have a lifespan of one year. Their entire purpose is to reproduce and they die after spawning. Shortfin squid still play a vital part in the oceans food chain, as they are a favored prey of many types of fish and marine mammals.
Horseshoe crab
Scientific Name: Limulus polyphemus
Appearance: Horseshoe crabs can grow to be quite large, around 2 feet in length. The females tend to be larger than the males. Like their name suggest, they are horseshoe shaped with a rounded, brown colored shell. Their bodies are divided into two parts, an anterior cephalothorax and a posterior abdomen. There is a joint in the shell between these two sections. They have a spike-shaped tail that function as a digging tool and a lever if the animal ends up on its back.
Horseshoe crabs have four pairs of jointed walking legs and fifth, larger pair that helps the animals lurch forward. They have ten eyes located all over their back and sides.
Diet: Horseshoe crabs are omnivorous scavengers. They will eat anything from mollusks and worms to dead fish and algae. The middle segment of each leg has spines that are used to chew food before it is passed into the mouth.
Location: The Limulus polyphemus is the only species of horseshoe crab found in the Atlantic. They are found off the U.S. east coast from southern Maine to the Gulf of Mexico. Horseshoe crabs prefer shallow waters in the summer and deeper waters during the winter.
While they are called “crabs”, these creatures are only distant relatives of crustaceans and are actually more closely related to arachnids (spiders, scorpions, ticks).
Horseshoe crabs blood is quite valuable to the medical community. A protein found in its blood is used to detect impurities in intravenous medications. It has also been used in cancer therapy research, leukemia diagnosis, and the detection of vitamin B12 deficiency.
Their tails are not always effective for righting themselves if they end up on their backs. Beachgoers are often encouraged to flip them back over should they find a stuck horseshoe crab. Despite their odd appearance, they are not dangerous to humans.
Appearance: Horseshoe crabs can grow to be quite large, around 2 feet in length. The females tend to be larger than the males. Like their name suggest, they are horseshoe shaped with a rounded, brown colored shell. Their bodies are divided into two parts, an anterior cephalothorax and a posterior abdomen. There is a joint in the shell between these two sections. They have a spike-shaped tail that function as a digging tool and a lever if the animal ends up on its back.
Horseshoe crabs have four pairs of jointed walking legs and fifth, larger pair that helps the animals lurch forward. They have ten eyes located all over their back and sides.
Diet: Horseshoe crabs are omnivorous scavengers. They will eat anything from mollusks and worms to dead fish and algae. The middle segment of each leg has spines that are used to chew food before it is passed into the mouth.
Location: The Limulus polyphemus is the only species of horseshoe crab found in the Atlantic. They are found off the U.S. east coast from southern Maine to the Gulf of Mexico. Horseshoe crabs prefer shallow waters in the summer and deeper waters during the winter.
While they are called “crabs”, these creatures are only distant relatives of crustaceans and are actually more closely related to arachnids (spiders, scorpions, ticks).
Horseshoe crabs blood is quite valuable to the medical community. A protein found in its blood is used to detect impurities in intravenous medications. It has also been used in cancer therapy research, leukemia diagnosis, and the detection of vitamin B12 deficiency.
Their tails are not always effective for righting themselves if they end up on their backs. Beachgoers are often encouraged to flip them back over should they find a stuck horseshoe crab. Despite their odd appearance, they are not dangerous to humans.
American lobster
Scientific Name: Homarus americanus
Appearance: A lobster’s normal coloring is usually a mix of brown, green, and red. On rare occasions, genetic mutations may cause some lobsters to be blue or white. They only turn bright red after they have been cooked.
Proportionally, these animals can be divided into three parts: claws, body, and tail. Their large claws are very strong and larger specimens are capable of doing humans a good deal of injury if they manage to latch onto a foot or hand. They have fairly long tails with a wavy-edged fan on the end. They have four pairs of walking legs and four pairs of swimmerets. It is possible for these animals to grow up to three feet in length.
Diet: Lobsters have a varied diet and will eat fish, crabs, smaller lobsters, clams, mussels, sea urchins, and sea stars.
Location: These lobsters are found all along the North American east coast, from Labrador to North Carolina. The largest populations are in the Gulf of Maine. They can live on any type of seafloor, but prefer rocky or muddy bottoms. Thanks to an increase in seawater temperatures lobsters populations in the Gulf of Maine have been increasing.
The lobster industry is one of the most profitable fisheries in the State of Maine. They are also one of Maine’s most famous industries.
Appearance: A lobster’s normal coloring is usually a mix of brown, green, and red. On rare occasions, genetic mutations may cause some lobsters to be blue or white. They only turn bright red after they have been cooked.
Proportionally, these animals can be divided into three parts: claws, body, and tail. Their large claws are very strong and larger specimens are capable of doing humans a good deal of injury if they manage to latch onto a foot or hand. They have fairly long tails with a wavy-edged fan on the end. They have four pairs of walking legs and four pairs of swimmerets. It is possible for these animals to grow up to three feet in length.
Diet: Lobsters have a varied diet and will eat fish, crabs, smaller lobsters, clams, mussels, sea urchins, and sea stars.
Location: These lobsters are found all along the North American east coast, from Labrador to North Carolina. The largest populations are in the Gulf of Maine. They can live on any type of seafloor, but prefer rocky or muddy bottoms. Thanks to an increase in seawater temperatures lobsters populations in the Gulf of Maine have been increasing.
The lobster industry is one of the most profitable fisheries in the State of Maine. They are also one of Maine’s most famous industries.
sand dollar
Scientific Name: Echinarachnius parma
Appearance: Sand dollars are brownish gray organisms. They are flat and wafer-shaped. Their bodies are covered with tiny spines, which gives them a velvet-like look and feel. An indentation that resembles a star is located on their skeletal test. Their mouths are a small opening on their bottom side.
Diet: Sand dollars eat by feeding on microorganisms are they move over the sand.
Location: Sand dollars live on the ocean floor from Labrador to New Jersey. They prefer to live on sandy bottoms.
Dead sand dollars often wash up on beaches. They are popular collectables for beach goers. Dead sand dollars will be dry and a pure off-white color with no brownish tint.
Appearance: Sand dollars are brownish gray organisms. They are flat and wafer-shaped. Their bodies are covered with tiny spines, which gives them a velvet-like look and feel. An indentation that resembles a star is located on their skeletal test. Their mouths are a small opening on their bottom side.
Diet: Sand dollars eat by feeding on microorganisms are they move over the sand.
Location: Sand dollars live on the ocean floor from Labrador to New Jersey. They prefer to live on sandy bottoms.
Dead sand dollars often wash up on beaches. They are popular collectables for beach goers. Dead sand dollars will be dry and a pure off-white color with no brownish tint.
Canada. (2009). Short-Finned Squid. Fisheries and Oceans of Canada. Retrieved from: http://www.dfo-mpo.gc.ca/science/publications/uww-msm/articles/shortfinnedsquid-calmaranageoirescourtes-eng.html
Jones, Elaine P., Grover, Dawn, Dumont, Peter, & Booker, James. (1993). A Teacher’s Guide to Marine Life of the Gulf of Maine. Maine Department of Marine Resources. Retrieved at: http://www.maine.gov/dmr/rm/aquarium/Teachers_Guide.pdf
MarineBio. (2014) Marine Invertebrates. Retrieved from: http://marinebio.org/oceans/marine-invertebrates/
Rehder, Harald H., (1981). Field Guide to North American Seashells. The Audubon Society. New York, New York: Alfred A. Knopf
NEA. (2014). American Lobster. New England Aquarium. Retrieved from: http://www.neaq.org/animals_and_exhibits/animals/american_lobster/index.php
Jones, Elaine P., Grover, Dawn, Dumont, Peter, & Booker, James. (1993). A Teacher’s Guide to Marine Life of the Gulf of Maine. Maine Department of Marine Resources. Retrieved at: http://www.maine.gov/dmr/rm/aquarium/Teachers_Guide.pdf
MarineBio. (2014) Marine Invertebrates. Retrieved from: http://marinebio.org/oceans/marine-invertebrates/
Rehder, Harald H., (1981). Field Guide to North American Seashells. The Audubon Society. New York, New York: Alfred A. Knopf
NEA. (2014). American Lobster. New England Aquarium. Retrieved from: http://www.neaq.org/animals_and_exhibits/animals/american_lobster/index.php
Updated: December 5, 2014